FINAL REPORT - Sri Lanka · FINAL REPORT ENVIRONMENTAL ... Figure 3:8 I: Anchoring boats along the...
Transcript of FINAL REPORT - Sri Lanka · FINAL REPORT ENVIRONMENTAL ... Figure 3:8 I: Anchoring boats along the...
DAM SAFETY AND WATER RESOURCES PLANNING PROJECT (DSWRPP)
Ministry of Irrigation and Water Resources Management
FINAL REPORT
ENVIRONMENTAL ASSESSMENT FOR REHABILITATION OF ANGAMUWA DAM
(DSWRPPAF/CS/QCBS/0305A)
By UNI CONSULTANCY SERVICES
UNIVERSITY OF MORATUWA
October 2015
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
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TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................... II
LIST OF ANNEXES ................................................................................................................... IV
LIST OF FIGURES .................................................................................................................... IV
LIST OF TABLES ...................................................................................................................... VI
ABBRIVIATIONS ...................................................................................................................... VII
1. CHAPTER 01 : INTRODUCTION ........................................................................................ 1
1.1 Project Description and Justification ..................................................................... 1
1.1.1 Background of the Project................................................................................ 1
1.1.2 Project Location ................................................................................................. 1
1.2 Scope of the Project and Environmental Assessment ....................................... 4
1.2.1 Scope of the Project ......................................................................................... 4
1.2.2 Environmental Assessment Requirements ................................................... 4
1.3 Objectives of the Study ............................................................................................ 4
1.4 Strategies to be Applied .......................................................................................... 4
1.5 Methodology .............................................................................................................. 5
1.5.1 Mobilization ........................................................................................................ 5
1.5.2 Scoping Meetings and Reconnaissance Visits ............................................. 5
1.5.3 Data and Information Collection ..................................................................... 5
1.5.4 Baseline Surveys ............................................................................................... 5
1.5.5 Institutional Arrangements ............................................................................... 7
1.5.6 Environmental Impact Analysis, Proposed Mitigatory Measures .............. 7
1.5.7 Documentation Procedure ............................................................................... 8
1.6 Expected Outcomes of the Report ....................................................................... 11
2. CHAPTER 02 : DESCRIPTION OF EXISTING ENVIRONMENT .......................................... 12
2.1 Overview .................................................................................................................. 12
2.2 Physical Environment ............................................................................................ 12
2.2.1 Climate .............................................................................................................. 12
2.2.2 Topography ...................................................................................................... 13
2.2.3 Soil and Geology ............................................................................................. 14
2.2.4 Hydrology.......................................................................................................... 15
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2.2.5 Flooding ............................................................................................................ 21
2.2.6 Noise and Vibration ......................................................................................... 21
2.2.7 Air Quality ......................................................................................................... 21
2.2.8 Water Quality ................................................................................................... 23
2.3 Biological Environment with Flora and Fauna ................................................... 23
2.3.1 Existing Habitats in the Project Affected Area ............................................ 23
2.3.2 Existing Flora and Fauna in the Tank and Surrounding Habitats ............ 23
2.3.3 Ecological Signifcance of the Proposed Borrow Areas ............................. 27
2.3.4 Migratory Paths................................................................................................ 29
2.4 Socioeconomic Environment ................................................................................ 29
2.4.1 Local Administrative Units in the Project Area ........................................... 29
2.4.2 Land Use in Different Areas of the Irrigation Schemes ............................. 30
2.4.3 Demographic Data Relevant to the Project Area ....................................... 30
2.4.4 Economic Activities of Project Related Population .................................... 32
2.4.5 Other Water Uses............................................................................................ 34
2.5 Current Environmental Issues of the Project Area ............................................ 35
2.5.1 Physical Issues ................................................................................................ 35
2.5.2 Ecological Issues ............................................................................................. 35
2.5.3 Socioeconomic Issues .................................................................................... 35
3. CHAPTER 03 : PROPOSED INTERVENTIONS ................................................................. 36
3.1 Proposed Engineering Interventions ................................................................... 36
3.2 Proposed Borrowing Activities and the Identified Borrow Sites ...................... 40
3.3 Proposed Interventions that could Affect Neighboring Communities ............. 41
3.4 Proposed Interventions that could affect the Natural Habitats ........................ 41
4. CHAPTER 04 : PROJECT INDUCED IMPACTS ................................................................ 42
4.1 Identification of Project Induced Impacts ............................................................ 42
4.2 Quantification of their Significance ...................................................................... 55
5. CHAPTER 05 : ENVIRONMENTAL MANAGEMENT PLAN ............................................... 56
5.1 General Overview ................................................................................................... 56
5.2 Identification of Impacts and their Mitigations .................................................... 56
5.3 Implementation Schedules of Proposed Mitigation ........................................... 75
5.4 Formal Clearances and Approval Needed ......................................................... 76
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6. CHAPTER 06 : MONITORING PLAN ............................................................................... 77
6.1 Environmental Compliance and Monitoring ....................................................... 77
7. CHAPTER 07 : COST ESTIMATE OF ENVIRONMENTAL MANAGEMENT PLAN .............. 82
8. CHAPTER 08 : CONCLUSIONS AND RECOMMENDATIONS ............................................ 84
8.1 Conclusions ............................................................................................................. 84
8.2 Recommendations ................................................................................................. 84
LIST OF ANNEXES
Annex 1: Details of the Farming Community ......................................................................... II
Annex 2: Details of the encroached farmer families ............................................................. IV
Annex 3: Land area in Gravity and Lift irrigation systems in Angamuwa tank ........................ vi
Annex 4: Details of the cost benefit of an acre of paddy land in Angamuwa tank ................. vii
Annex 5: Annex 5: Map showing the vicinity of Angamuwa tank………………………………viii
Annex 6a & b: Location map for the identified quarry and borrow sites for Angamuwa tank .. ix
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LIST OF FIGURES
Figure 1:1: Location Map of the Angamuwa Tank (Source: Survey Department, 1:50,000
Topo sheet) ........................................................................................................................... 2
Figure 1:2: Google Map Showing the access to Angamuwa Tank from Anuradhapuraya ...... 3
Figure 2:1: Monthly Average Rainfall in Rajanganaya tank catchment area during 2009 -
2014 (Source Divisional Irrigation Office, Rajanganaya) ..................................................... 13
Figure 2:2: Contour Map of the Project Area (Angamuwa Tank is locted beneath 40 m
contour line) ........................................................................................................................ 14
Figure 2:3: Distribution of Soil Groups (Panabokke, 1975) .................................................. 15
Figure 2:4: Land Use and Hydrological Features of the Angamuwa Basin .......................... 17
Figure 2:5: Location Map and Associated Hydrologic Features of Angamuwa .................... 18
Figure 2:6: Catchment of Mahavilachchiya within Modaragam aru-Uppu Aru Main Basin ... 19
Figure 2:7(a): Catchment of Angamuwa within Modaragam aru-Uppu Aru Main Basin ....... 19
Figure 2:8 (b): Catchment of Mahavilachchiya within Angamuwa aru-Uppu Aru Main Basin 20
Figure 2:9: Vegetation on the Dam...................................................................................... 24
Figure 2:10: Water logged or marshy lands in the downstream area of the tank bund......... 25
Figure 2:11: Rocky outcrop and associate vegetation ......................................................... 25
Figure 2:12: Tank and Irrigation canals ............................................................................... 26
Figure 2:13: Proposed gravel borrow area .......................................................................... 28
Figure 2:14: Proposed borrow site for earth extraction ........................................................ 28
Figure 3:1.1A: Washed away U/S slope and rip rap collapsed in some areas ..................... 38
Figure 3:2 B: Seepage areas along the D/S toes ................................................................ 39
Figure 3:3 C: Water stagnating at the dam .......................................................................... 39
Figure 3:4 D: Encroachments at the dam ............................................................................ 39
Figure 3:5 F: The bund road is with lots of pot holes and eroded places ............................. 39
Figure 3:6 G: Structural failures of the spillway such as failure of abutments, sliding of
sections............................................................................................................................... 39
Figure 3:7 H: Leakage through right wing wall of sluice and suspected areas in U/S .......... 39
Figure 3:8 I: Anchoring boats along the U/S slope of dam cause bund erosion and scouring
........................................................................................................................................... 40
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List of Tables
Table 1.1: The Method used for Impact Assessment............................................................. 6
Table 1.2: Work Plan............................................................................................................. 9
Table 2.1: Maximum Permissible Levels for air pollutants as given in The National
Environmental (Ambient Air Quality) Regulations, 1994 (amended 2008), and actual
measured air quality in Anuradhapura Town ....................................................................... 22
Table 2.2: details of the local administrative units related to the project .............................. 29
Table 2.3: Details of Project Relevant Population ................................................................ 31
Table 2.4: Distribution of Income Generation Activities among Families in Project Related
Villages ............................................................................................................................... 33
Table 2.5: Details Expressed by the Farmer Leaders .......................................................... 34
Table 3.1: Current issues in Angamuwa Tank Bund ............................................................ 36
Table 3.2: Location Details of the Identified Borrow Sites .................................................... 40
Table 4.1: Possible Impacts due to the Proposed Interventions and their Significance........ 43
Table 5.1: Proposed Mitigatory Measures for the Identified Impacts ................................... 57
Table 5.2: Formal Clearances and Approval Needed .......................................................... 76
Table 6.1: Summary of Monitoring Requirement ................................................................. 78
Table 7.1: Cost Estimate of EMP ........................................................................................ 82
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ABBRIVIATIONS
AMSL - Average Mean Sea Level
BPL - Below Poverty Level
CEA - Central Environment Authority
D/S - Down Stream - Down Stream
DBH - Diameter at Breast Height
DEM - Digital Elevation Model
DS Division - Divisional Secretariat Division
DSWRPP - Dam Safety & Water Resources Planning Project
EA - Environmental Assessment
EMP - Environmental Management Plan
EN - Species - Endangered Species
EPL - Environmental Protection License
FD - Forest Department
FFPO - Fauna and Flora Protection Act
GND - Grama Niladari Division
GoSl - Government of Sri Lanka
GPS - Global Positioning System
GSMB - Geological Survey and Mines Bureau
GTOP030 - Global 30 Arc=Second Elevation Data-Set
ICTAD - Institute for Construction Training and Development
ID - Irrigation Department
IDF - Intensify Durative Frequency Curve
IDF Curves - Intensity Duration Curves
IEE - Initial Environmental Examination
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IML - Industrial Mining License
IUCN - International Union for Conservation of Nature
LB - Left Bank
KPI - Key Performance Indicators
MSL - Mean Sea Level
NEA - National Environmental Act
PM - Project Manager
PO - Project Office
PS - Pradeshiya Sabha
RB - Right Bank
STRM - Global Multi Resolution Terrain Elevation Data
TEC - Technical Evaluation Committee
ToR - Term of Reference
U/S - Up Stream
VU Species - Vulnerable Species
WB - World Bank
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TEAM OF CONSULTANTS FOR EA STUDY
Name Position
Eng. (Dr.) Mahesh
Jayaweera
Environmental Engineer/Civil Engineer (Team Leader)
Eng. (Dr.) Jagath Manatunge Natural Resources Management Specialist
Dr. Anusha Kasige Ecologist (Flora, Fauna and Ecosystems)
Mr. K. Jinapala Sociologist/Socio-economist
Uni-Consultancy Services Project Management
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1. CHAPTER 01 : INTRODUCTION
1.1 Project Description and Justification
1.1.1 Background of the Project
Over 350 large/medium dams, headwork and trans-basin canals of Sri Lanka are aging and
suffering from various structural deficiencies and shortcomings in the operation and monitoring
facilities. Thirty-two dams have been identified as high risk with respect to their appurtenant
structures and operational efficiency. Those dams are required to have immediate interventions so
as to decrease the vulnerability of downstream populations and socioeconomic infrastructure, if
breached. This situation threatens the safety and operational efficiency of the dams and their
appurtenant structures and as a result increases the vulnerability of breaching.
The Dam Safety & Water Resources Planning Project (DSWRPP) intends to address these issues
through its dam safety and operational improvement component with financing from the World
Bank. The main objectives of the proposed project are to improve the development and
management of water resources within the country, reduce water induced hazards to public, and
enhance the effectiveness of water related investments. The proposed project intends to address
these objectives in 29 dams through its dam safety and operational improvement component.
For these objectives are to be met, there will be some interventions to be carried out. These
interventions may bring about environmental degradations, environmental issues in terms of
physical, ecological or/and social changes, alterations or irreparable losses. Hence, the project
needs to identify such environmental issues that are very likely and they should be reduced or
curtailed as practical as possible. The proposed assignment is therefore meant to address such
issues and the whole exercise is defined by the Term of Reference (ToR) which sets out the likely
problems associated with five dams that are operated by the Irrigation Department and Mahaweli
Authority under whose jurisdiction remedial actions would be proposed. The dams have been
selected based on comprehensive risk assessment studies carried out as part of project preparation
from a list of vulnerable dams in order to ensure their structural and functional safety. With the ToR
it is expected to carry out Environmental Assessments for the proposed interventions under the
DSWRPP for Padaviya, Angamuwa, Mahavilachchiya and Mahakanadarawa dams.
The World Bank (funding Agency) and Dam Safety & Water Resources Planning Project
(DSWRPP) have agreed that the four dams earmarked for rehabilitation under this study need only
an Environmental Assessment (EA) together with an Environmental Management Plan (EMP) as
the proposed rehabilitation works do not entail any significant civil works.
1.1.2 Project Location
The Angamuwa tank bund operates under Irrigation Department and located in the Anuradhapura
district and the Rajanganaya Divisional secretariat (DSD) of the North Central Province (Figure 1.1
and Figure 1.2).
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Figure 1:1: Location Map of the Angamuwa Tank (Source: Survey Department, 1:50,000 Topo sheet)
Angamuwa
Tank
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The Angamuwa tank is a medium size tank which operates under Anuradhapura Regional by
Rajanganaya Divisional Irrigation Engineer (DIE). This tank can be accessed through
Anuradhapura - Kebithigollewa Road (Figure 1.2).
Figure 1:2: Google Map Showing the access to Angamuwa Tank from Anuradhapuraya
The Angamuwa dam is an ancient dam built across a tributary of Kalaoya and restored in 1956.
This is an Earth dam having a length of 1,700 m and the maximum height is 8 m. The U/S and D/S
slopes are 1:2.5, FSL is 211 ft msl and the HFL is 215.6 ft msl. The capacity of the reservoir is
12,800 ac. ft and the irrigable area is 2,466 ac. The spillway of the dam is of masonry ogee type
with a length of 234 m which consist of 02 radial gates. The dimensions of the radial gates are 20ft
x 10ft and the sluice is located at the right end of the dam which made up of rubble masonry. The
water release from Angamuwa tank is feeding lower part of the Rajanganaya command area, while
feeding the RB main canal of Rajanganaya reservoir.
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1.2 Scope of the Project and Environmental Assessment
1.2.1 Scope of the Project
The technical scope of the study is to carry out an environmental assessment based on the
identified interventions and their associated issues for the Angamuwa dam. The interventions to be
carried out during the rehabilitation work have already been defined at the inception stage of the
project based on the conceptual designs done by respective engineers. The present study focuses
on conducting the Environmental Assessment covering physical, ecological and socioeconomic
environment.
1.2.2 Environmental Assessment Requirements
This environmental assessment is prepared in pursuant to the World Bank’s Environmental
Safeguard Policies as outlined in OP/BP 4.01 and that of Safety of Dams OP/BP 4.37.
The overall objective of the proposed environmental assessment is to carry out the following
conforming to the World Bank’s Environmental Safeguard Policies and Procedures. For each dam,
an Environmental Management Plan will be prepared to address the objectives specified as given
below.
1.3 Objectives of the Study
The objectives of this assignment are to:
i. Identify and evaluate the potential environmental impacts that would arise as a result of the
proposed interventions
ii. Recommend appropriate mitigation measures to avoid, minimize, remedy or compensate
for the predicted negative impacts; and
iii. Provide a site-specific Environmental Management Plan that would give adequate project
options in terms of mitigation measures, project alternatives and a monitoring program to
achieve overall environmental sustainability of the project.
1.4 Strategies to be Applied
The strategies on which the environmental assessment will be done are based on the World Bank
Safeguard Policies and the National Environmental Act (NEA).
These environmental assessments are prepared in accordance with the World Bank’s
Environmental Safeguard Policies OP/BP 4.01 and that of Safety of Dams OP/BP 4.37. No
environmental assessment is required in accordance with NEA as the interventions do not belong to
categories that require either IEE or EIA. This had been confirmed by the Central Environmental
Authority.
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1.5 Methodology
1.5.1 Mobilization
The team of experts from Uni Consultancy Services of Moratuwa University commenced work on
20th November, 2014 with a meeting of team members where the Team Leader briefed the team
members on the methodology for executing the consulting services. Documents required for the
study were also identified and team members were requested to collect those pertaining to their
areas of expertise. The team leader thereafter prepared the Scope of Work for all team members to
ensure that the quantum of work to be carried out would be done in an appropriate manner.
Documents pertaining to the ecological resources of the project area, topography, climate, geology,
soil, demography and other relevant data were collected and reviewed as an initial activity. The
reconnaissance survey was carried out from the 23rd to 25th of November 2014. The team visited all
the dams and their project areas. The team visited on individual capacity several times to gather
and collate necessary data from time to time.
1.5.2 Scoping Meetings and Reconnaissance Visits
The Consultants visited the five dams to observe the present conditions of the dams and to
understand the nature of the issues (Table 3.1). Initial discussions were held with the engineers and
other field officers in the Irrigation Department to gain clear understanding of the issues mentioned
in the ToR and to gather related information and design details that were available at the times of
visits.
1.5.3 Data and Information Collection
A detailed literature review of available data was done by the team of consultants at the project
initiation. Relevant data to identify impacts were collected during a reconnaissance visit as and
when available, and also desk studies. The data gaps were identified and the detailed field plan
was prepared to carry out baseline surveys.
1.5.4 Baseline Surveys
The study area of the assessment included the dam area, peripheral area (500 m minimum),
borrow areas, work site and any area beyond the project site where there is potential for
environmental impacts and off-site locations affected by construction activities.
Most of the physical assessment was restricted only to the exact sites where interventions are
applied and in some of the borrow sites. Erosion, flooding, noise and vibration issues, air quality
issues, water pollution potential, etc. were some of the attributes that were studied under the
physical assessment. Rainfall data, flood data if available, data on soil and geology, noise levels
were collected in order to understand the existing situation of the tank area.
An ecological survey was carried out to describe the existing baseline conditions to evaluate and
illustrate the magnitude of the problem. This identified the major habitats / flora and fauna in and
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around the sites and to assess possible ecological impacts, existing environmental problems within
the proposed project areas. The study area was confined to the specific locations and immediate
surroundings directly affected by the activities. Under this part of the study, all trees of larger size
that need to be felled down were identified. The borrow areas were too scrutinized for the same
purposes in order to ensure no invasive species are transferred to the project site.
Methodology of social assessment mainly included the field visits of the sociologist and his
supporting staff with the other disciplinary team members that helped to gather primary and
secondary data. The stakeholders such as Irrigation Department, farmer organizations, fishing-
community, Grama Niladhari, affected people, beneficiaries and other direct and indirect users of
water in the reservoir were consulted to obtain data and their concerns related to the proposed
project. The Farmer Organization leaders and some general farmers were interviewed and the
details of them are shown in Annex 1.
Social surveys and related studies were carried out covering all the stakeholders, especially the
farmers and fishing communities in addition to other water users (e.g., villagers who use the water
for day-to-day activities, and/or other purposes). Grama Niladharis, Economic Development
Officers, Samurdhi Niyamakas, officials of the farmer organizations, and any other governmental
officers who are directly or indirectly involved with the functioning of the dam and its water
resources (such as the Divisional Secretariat, Irrigation officials, Agrarian Services Department etc.)
were also contacted. Data and information gathered from such social surveys were based to
identify and assess social impacts. Mitigation measures were proposed with clear justifications
based on the expectations of the stakeholders.
The socioeconomic data analysis was focused on the existing beneficial uses that would be
impacted due to each proposed development intervention. The method used for impact assessment
is mentioned in Table 1.1.
Table 1.1: The Method used for Impact Assessment
Issue to be dealt with Indicators Data Need
Livelihoods of the farming
community
No of farmers to be affected
The land parcels to be affected
(encroached land in the
downstream and upstream of the
reservoir)
under Details of cultivators the
tank, yield and income, details
on encroachments of the
reservations.
Other indirect livelihoods
No of water users affected
No of farming facilities affected
No of families using tank water for
bathing and washing
Data on the other water uses in
the tank
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Issue to be dealt with Indicators Data Need
Disturbance to other
routine activities of the
communities in the project
area
No of people of the villages using
the tank bund as the access road
Data on users of the tank bund
as access road
1.5.5 Institutional Arrangements
The Acts, regulations, licenses, permits and other approvals that may be necessary for the
implementation of the proposed interventions were identified. These may include;
i. Irrigation Ordinance No. 32 of 1946 Irrigation (Amendment) No. 1 of 1951 Irrigation
(Amendment) No. 48 of 1968 Irrigation (Amendment) No. 37 of 1973 Agrarian
Development Act, No. 40 of 2002
ii. The National Environmental Act (NEA) No. 47 enacted in 1980 and NEA Amendment Act
No. 56 of 1988
iii. National Environmental Protection and Quality Regulations under extraordinary gazette
notification No. 1534/18 and No. 1533/16 of 2008 under NEA section 32 & 23A, 23B
iv. Fauna and Flora Protection Act (FFPO) No.2 of 1937 amended in 1993 and 2009
v. Felling of Trees Control Act No. 9 of 1951 as amended through Act No. 30 of 1953
vi. Water Resources Board Act, No. 29 of 1964 and (Amendment) Act, No. 42 of 1999
vii. Soil Conservation Act, No. 25 of 1951 and Amended No. 24 of 1996
viii. Agrarian Development Act No. 46 of 2000 (Section 32)
ix. Antiquities Ordinance No. 9 of 1940 and amendments
x. Mines And Minerals Act (No. 33 of 1992)
xi. Mahaweli Authority of Sri Lanka Act of 1979
xii. World Bank Guidelines pertaining to Dam Safety & Environment Assessment Guidelines
It is also imperative that the proper institutional arrangement be made available for smooth
operations of the EMP. It is the Project Office that is in charge of the entire project and the client,
Irrigation Department would be solely responsible in getting the project implemented with a selected
contractor. The contractor will be selected through a bidding process and the contractor is
responsible in implementing the EMP delineated herein this report. During the project
implementation period, the World Bank and the Project Office will evaluate the implementation of
the EMP. Once the EMP is implemented as per the World Bank Safeguard Policy Documents,
review of implementation of EMP would be done in order to ensure that all negative impacts are
addressed successfully.
1.5.6 Environmental Impact Analysis, Proposed Mitigatory Measures
Environmental impacts of the proposed project were identified during field investigations and
through the analysis of project interventions. Their significance was assessed on physical,
ecological and socio-economic resources due to project activities during construction and operation
phases. The World Bank Environmental Safeguard Policies and applicable GoSL laws and
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regulations were followed in identifying and quantifying such impacts.
A site-specific EMP that would provide mitigation strategies, project alternatives and a plan for
monitoring program was prepared. Proper management of the catchment and the watershed that is
essential for ensuring continued economic benefits envisioned from the dam was paid due attention
in quantifying the impacts. These were also considered in the EMP.
1.5.7 Documentation Procedure
The following documents are to be prepared and delivered to DSWRPP.
i. Inception Reports for each Dam
Already submitted to the Project Office and approval was obtained.
ii. Draft Final Reports for each Dam
The Final Report includes the following:
a. A comprehensive Environmental Management Plan (EMP) to manage the on-site as well
as off-site environmental impact comprising mitigation strategies for each impact identified
b. Appropriate institutional arrangement to implement the proposed measures
c. Implementing schedule
d. Reporting procedures
e. Cost estimates for implementing mitigation measures
f. An environmental monitoring plan that will specify monitoring indicators to measure the
performance of the each mitigatory measure, monitoring mechanism and frequency.
g. Clearance approvals needed by the project prior to its implementation
h. Recommendations on the adequacy of the assessment
i. Final conclusions and recommendations in response to environmental viability, of the
project based on the findings
j. Annexure and Appendices
iii. Submission of Final Reports
The Final Report will be submitted within two weeks after receiving comments from the client once
the TEC evaluates and reviews the Draft Final Report. The final report will be reviewed by the
World Bank as well.
The main activities to be followed to complete above deliverables are summarized in Work Plan
given below (Table 1.3).
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Table 1.2: Work Plan1
Activity Month Nov
’
201
4
December
2014
January
2015
February
2015
March 2015 April 2015
Week 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
1 Primary Data Collection
2 Reconnaissance Survey
3 Meetings to discuss about
intervention/designs
4 Develop the detailed methodology
5 Scoping of environmental impacts
6 Submission of the Inception Report
7 Detailed field visits (Chapter 2 & 3)
8 Assessment of Anticipated Environmental
Impacts (Chapter 4)
1 Submission date of the Final Report is extended to the 25th of April 2015 in the meeting with DSWRP Project Officials held at Mahaweli Authority on 12th Feb. 2015
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9 Formulation of the Environmental
Management Plan (Chapter 5)
1
0
Identification of needs/approvals to
implement EMP (Chapter 5)
1
1
Drafting of Environmental Monitoring Plan
(Chapter 6)
1
2
Cost Estimates (Chapter 7)
1
3
Compilation of Conclusions and
Recommendations (Chapter 8)
1
4
Compilation & Submission of the Draft
Final Report
1
5
Compilation & Submission of the Final
Report
.
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1.6 Expected Outcomes of the Report
The expected outcomes are categorized as follows.
a. Comprehensive Environmental Management Plan (EMP) to manage the on-site as
well as off-site environmental impacts
b. An environmental monitoring plan that will specify the monitoring indicators to
measure the performance of the each mitigatory measure, monitoring mechanism
and frequency
c. Clearance approvals needed by the project prior to its implementation
d. Recommendations on the adequacy of the assessment
e. Recommendations regarding the environmental viability of the project based
findings
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2. CHAPTER 02 : DESCRIPTION OF EXISTING ENVIRONMENT
2.1 Overview
It is imperative that the existing environment in the project area and the borrow areas are
identified in terms of different environmental elements. In order to perceive the likely
alterations of the existing environment due to the proposed interventions present status of
the existing environment needs to be recorded and then the impacts on such elements need
to be discussed.
In general, the entire existing environment is described in three main components, namely,
physical, ecological and socioeconomic environments respectively. Data were collected
focusing on these three components and are presented below.
2.2 Physical Environment
2.2.1 Climate
The Angamuwa tank is located in dry zone where the environment of the area consists with
dry and hot climatic conditions throughout the year. The climate of the Angamuwa is typical
to that of Anuradhapura district.
Temperature, which is warm throughout the year, shows little variation over the year and
between places in the district. The annual average temperature is 27.3oC. Humidity is an
important climatic consideration, which expresses the degree of dryness or wetness of the
air. The relative humidity varies in 70 – 82% within the year.
The rainfall generally follows a bimodal pattern of distribution. The major one of the two
rainfall peaks is spread over a period of three months commencing between late September
and mid October and extending to late December or up to mid January. These are called as
Maha rains, and due to relatively long period of rain filling the tanks and even causing
floods. As the Maha rains fade away, a dry season sets in during which period there is little
or no rain, in March soil dries up, the forest becomes less lush and the season turns less
tranquil. During the dry season decline the water reserves within the district. The second
rainy season of the year begins any time from mid March to mid April and lasts until May or
even June, which is called Yala rain corresponding to Yala season. This is shorter
compared to Maha rain. This rain replenishes the depleted tanks and ground water reserves
to a substantial level. When the short wet season is over, dry weather sets in again from
May or June. In August, the condition of the climate is arid, tanks are dried up, and the mud
is lined cracked. However, this district receives an annual average rainfall of 1,420 mm,
which is high enough in Maha season and mainly by North East monsoonal component.
The monthly average rainfall recorded in the Rajanganaya tank catchment area, which is the
closest rainfall station to Angamuwa tank, for the last 5 years is shown in Figure 2.1.
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Figure 2:1: Monthly Average Rainfall in Rajanganaya tank catchment area during 2009
-2014 (Source Divisional Irrigation Office, Rajanganaya)
Unlike rainfall the temperature, which is warm throughout the year, shows little variation over
the year and between places in the district. The annual average temperature is 27.3oC.
Humidity is an important climatic consideration, which expresses the degree of dryness or
wetness of the air. The relative humidity varies between 70 – 82% within the year. During
the South Western monsoons, the wind speed accelerates to 12 km/hr or it rises further to
16 km/hr.
2.2.2 Topography
The general topography of Sri Lanka comprises of three distinctive peneplains or erosion
plains made up of a central highland massif rising above 2,500 metres in altitude and a low
gently undulating plain surrounding it and extending to the sea. The lowest peneplain
extends from the coastline to approximately 20-30 kilometres inland in a steep step of about
300 meters above mean sea (MSL). Angamuwa is located in the North Central Province,
lies within this lowermost peneplain. The landscape in the vicinity of the site is characterized
by flatlands, with almost no altitude changes, partly due to the fact that the land has already
been cleared and prepared for the agriculture, secondary development with people in-
migrating to these areas recently. According to the pre-existed topography, the elevation in
the proposed site area had varied from 110 m MSL in the northestern boundary to 40 m
MSL in western edge, with a gently sloping landscape in the western and south-west
direction (Figure 2.2).
0
100
200
300
400
500
600M
on
thly
ave
rage
Rai
nfa
ll (m
m)
2009
2010
2011
2012
2013
2014
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Figure 2:2: Contour Map of the Project Area (Angamuwa Tank is locted beneath 40 m
contour line)
At a larger scale, the present topographical variation is somewhat different. The elevation
towards the south eastern areas (Tambuttegama) have higher ground propagating up to 100
m, whereas south western areas have lower elevations dropping to below 40 - 50 m towards
Kalaoya and Wilpattuwa area (western direction). The downstream of the tanks is
characterized by very gentle slopes with 0.5% – 1.0 % surface gradient in the north-western
direction (Figure 2.2).
2.2.3 Soil and Geology
According to the Geomorphological Map of Sri Lanka (1987/88), the area is located between
the boundary of hornblende gneiss and low plantation surfaces with thin soils (dry zone).
The soil types that are dominant in the area are dominantly reddish brown earth, low humic
gley soils and non-calcic brown soils (see figure 2.3) and regosols and alluvial soils in some
places in the subsurface layers. Predominant rocks are Precambrian, essentially gneissic
and crystalline rocks. Main rocks are Vijayan and Wanni series rocks of the Precambrian
and the Palaeozoic eras.
Up to 90% of the subsurface geological structure of Sri Lankan territory mainly consists of
highly crystalline, non-fossilifferous rocks of Precambrian age with a history of over 500
million years. The broad coastal plains of south-western Sri Lanka, along with the southern
India, are founded on these basement rocks (mainly basic igneous intrusive) on the lower
margin of a broad syncline which tilts downwards to the southwest and also known as one of
the most stable parts of the earth’s crust of the Indian shield. On the basis of the rock types
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and structure, they are divided into three main complexes; namely, Highland Complex (HC),
Wane Complex (WC) and Vijay an Complex, and one subordinate unit Kadugannawa
Complex (KC).
Soils in the proposed site area are mainly of Non Calcic Brown with the top soil texture
varying from dark brown and dark grayish brown to brown or yellowish brown in the
subsurface layers. Predominant rocks are Precambrian, essentially gneissic and crystalline
rocks. Main rocks are Vijayan and Wanni series rocks of the Precambrian and the
Palaeozoic eras.
Figure 2:3: Distribution of Soil Groups (Panabokke, 1975)
2.2.4 Hydrology
The hydrology in the proposed site area is mainly governed by seasonal streams, cascade
system man-made reservoirs and associated irrigation canals. Surface water resources in
the project area mainly consist of inland reservoirs, which are used for water storage,
irrigation, and drinking water supply. Many such small reservoirs are located to the south
along the 2.0 km borderline and several minor tributaries of length 0.3-0.6 km are found,
draining the relatively high stretches in the middle of the 2.0 km radius circle peripherally
outwards in the downstream direction. Dendritic drainage pattern could be observed in the
area, with several waterways and man-made canals inter-connecting small reservoirs and
irrigation service canals via anicuts and sluices. Groundwater is used for daily needs
through dug wells. The depth of the groundwater table in the vicinity of site area is known to
vary from 3 m to 5 m and a definite seasonal variation could be expected in the groundwater
table following the rainfall regime.
According to the terrain contour layout, the gravity drainage in the proposed site area is in
western direction (Figure. 2.2), which is linked to the lower valleys of Aruvi-Ara and
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Modaragam aru- Malwathu Oya. However, it is noted that there is no proper off-site
drainage route provided at present and the entire drainage from the surrounding area is
naturally channeled either to the small stream (North-West or conveyed to North-East
direction, across the sloping ridge. Due to the subsequent leveling and land preparation
activities carried out at site with stepped land plot set up with slopes maintained in north-
west direction has restored the similar flow regime with same flow directions. However, it
was noted that the surface drainage and culverts provided at the site at present are under
designed and tend to over flow even during regular rain events.
The main data required for the hydrological and hydraulic assessments apart from the
topographic information are;
Rainfall Intensity-Duration-Frequency Curves (IDF Curves) for catchment areas
Information on runoff coefficients and time of concentration
The site is situated in the belt of monsoon climates and governed by its tropical location as
well by the monsoonal regime, thus rainfall exhibits a strong seasonal variation. The area
falls under the dry zone and receives a long-term mean precipitation of which 75%
expectancy value of annual precipitation is > 900 mm. More than 50% of the total rainfall is
received during the Second Inter Monsoon and North-Eastern Monsoon (October to
December).
The sub-catchment area is presumably not subjected to any flooding under seasonal
monsoonal storm event, except for extreme events where backwater flows from downstream
accumulation due to flow constrictions may cause localized temporary inundation in some
areas. Historical flood data are not available in the area.
The topographic data with contours and road layout has been obtained from the Survey
Department. Topographic maps with 1: 50,000 scale were primarily used (1: 10,000 maps
were not available) together with the collected Global Positioning System (GPS) coordinates
to locate the manor canals and structures while supplementary topo - and land use
information from Google Earth maps, Google terrain data and other relevant images have
also been obtained as required. The SRTM/GTOPO30 (USGS) global raster satellite DEM
(Digital Elevation Model) data were downloaded and used in identifying sub-/major
catchments in the region. These maps and terrain data in combination with identified land
use data were used to distinguish and demarcate respective catchment areas for the tank
under consideration. In the present version of the analysis, a 5.0-m interval contour map in
the coastal to upstream regions, developed based on DEM data from GTOPO30 and
modified with SRTM (Refined) arc 3.0 data has been used in initial catchment demarcation
(Figure 2.3 – 2.8).
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Figure 2:4: Land Use and Hydrological Features of the Angamuwa Basin
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Figure 2:5: Location Map and Associated Hydrologic Features of Angamuwa
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Figure 2:6: Catchment of Mahavilachchiya within Modaragam aru-Uppu Aru Main
Basin
Figure 2:7: Catchment of Angamuwa within Modaragam aru-Uppu Aru Main Basin
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Figure 2:8 : Catchment of Mahavilachchiya within Angamuwa aru-Uppu Aru Main
Basin
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2.2.5 Flooding
Past flooding records indicated that the project area was flooded particularly in the recent
past for a height of 2-3 feet. However, water level recedes soon after the rainfall ceases as
the direct catchment seems to be small compares to those of adjacent ones. However,
during flooding, people in the area find difficult to travel in the area.
The ground level of the project area is about +60 m above MSL and the surrounding low
lying valley, manmade water bodies, and natural waterways are at about +60 - 70 m above
MSL. No past records are available on occurrence of flooding and return periods, however,
the water levels had not reached beyond 60 m above MSL, even in the aftermath of
torrential rains in January-February 2011 that triggered unprecedented floods in
Anuradhapura and other nearby districts, also causing a large number of reservoirs to reach
their spill levels simultaneously, presumably for the first time in recent history after a similar
event in 1958 (Source: Irrigation Department, Ministry of Irrigation & Water Resources
Management, Sri Lanka). Available past rainfall records indicate that the accumulated
precipitation in the February 2011 event surpasses the 60-year return period flood event.
Therefore, no risk of flood inundation is foreseen in the proposed site area.
No past records are available on occurrence of flooding and return periods in the proposed
site area. However, minor floods have been recorded in the downstream valley area once in
3-4 years with up to 1 – 2 feet (0.3 – 0.6 m) of stagnant water due to downstream control of
increased water level in the inlet to Mahavilachchiya Wewa, however the maximum
inundation period was less than 2-3 days, during such recent flood events.
No records are available of occurrence of floods of this magnitude in the area for the past
100 years. However, the low lying flatland surrounding a section of the main entrance to the
site resembles a natural depression and seemingly becomes flooded during heavy rains,
causing a temporary problem of inundation.
2.2.6 Noise and Vibration
Background noise levels in the area were found to be very low varying in the range of 40 –
54 dB (A) during the site visit, indicating that no any artificial noise levels be generated in the
project area. The existing noise levels are attributed by the noise generated from the rattling
of leaves of trees by the wind and the occasional screech of birds passing and roosting in
the area.
No significant vibration levels were perceived during the field visit indicating that vibration
induced activities were almost absent.
2.2.7 Air Quality
Air quality in the entire study area appears to be good. However, there is a chance of
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deteriorating temporarily the air quality along the transport routes due to traffic congestions.
The major source of atmospheric pollution in the area is from road traffic especially heavy
vehicles in the form of diesel and petrol engine vehicle fumes. Domestic sources of air
pollution will include emissions from burning of forest patches for Chena cultivation, wood
and kerosene burning stoves in settlements, villages and town areas. Also, emanation of
dust from the gravel quarry sites existing in the project area would contribute to air pollution.
Any such emissions will be very well dissipated in the open terrain and absorption by forest
vegetation. Air quality parameters measured in Anuradhapura city is presented in Table 2.1.
Since the surrounding areas of the proposed site is mostly surrounded by the homesteads,
small forested patches and rural settings, the ambient air quality in the vicinity should fall
within the limits of The National Environmental (Ambient Air Quality) Regulations, 1994
(amended 2008). Ambient air quality had been measured by the Central Environmental
Authority in 1999 (reported in Environmental Atlas of Sri Lanka in 2005), and their
observations are included in Table 2.1.
Table 2.1: Maximum Permissible Levels for air pollutants as given in The National
Environmental (Ambient Air Quality) Regulations, 1994 (amended 2008), and actual
measured air quality in Anuradhapura Town
Pollutant Maximum Permissible
Level
Air pollutant levels measured in
Anuradhapura Town
(Source: Environmental Atlas of Sri Lanka,
2005)
Average Maximum
NO2 0.13 ppm (1 hr) 0.005 ppm (1 hr) 0.01 ppm (1 hr)
SO2 0.08 ppm (1 hr) 0.003 ppm (1 hr) 0.012 ppm (1 hr)
CO 26 ppm (1 hr) 1 ppm (1 hr) 2.5 ppm (1 hr)
PM10
PM2.5
100 µg/m3 (Annual)
50 µg/m3 (Annual)
30 µg/m3 (1 hr)
Not measured
40 µg/m3 (1 hr)
Not measured
O3 0.10 (1 hr) Not measured Not measured
In view of the above observations it was evident that all air pollutant levels in Anuradhapura
are well below the permissible levels even though the road traffic especially heavy vehicle
movement has been reported to be moderately high within the City limits. Therefore, we can
safely extrapolate this observation and conclude that the air quality in the vicinity of the site
and surroundings are well-below the observations obtained for Anuradhapura and below
Maximum Permissible Levels.
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2.2.8 Water Quality
The water quality of the tank seems to be not degraded significantly even with moderate
levels of anthropogenic activities that are found to be accruing in the surrounding of the
tank. However, slight turbidity issues were seen during the site visit, particularly in the area
of rip rap as the soil underneath was stirred up due to wind induced currents striking the rip
rap. This issue was very much localized and was not considered to be an adverse issue for
aquatic ecosystems. Nevertheless, it was mentioned by the villagers that during the windy
periods, there have been a substantial level of turbidity that could be found as the rip rap
was not properly placed in certain sections. In other words, soil particles beneath the rip rap
are washed off, causing turbidity plumes in the local areas resulting in smothering effects on
fauna. This scenario in the long run may tend to fail the rip rap completely in different
sections, hence neglecting corrective actions in the long run may create safety issues.
Other than the sporadic turbidity issues there have not been other water quality issues
reported in the tank.
2.3 Biological Environment with Flora and Fauna
2.3.1 Existing Habitats in the Project Affected Area
Biogeographically, the Angamuwa dam located within the low country dry zone. Floristically
it is under Dry and Arid Lowlands Floristic Zone and Tropical Dry Mixed Evergreen Forests
{Manilkara Community, Mixed community (Chloroxylon-Vitex-Berrya-Schleichera series)},
Tropical Thorn Forests (Manilkara-Chloroxylon-Salvadora-Randia series), Damana and Villu
Grasslands, Flood-plain Wetlands, Riverine and Gallery Forests are typical natural
vegetation formations in the Dry and Arid Lowlands Floristic Zone.
However, none of the above mentioned typical natural vegetation formations are not exists
in the dam area as the area is highly man modified. Dam and associate vegetations
(vegetations on the dam, vegetation associate with water logged or marshy lands in
downstream area, vegetation associate with rocky outcrop, cultivated lands and home
gardens in downstream area), tank and irrigation canals, vegetations in the tail canal are
major existing habitats / vegetations in the dam area. Secondary scrublands and seasonal
marshy vegetation can be observed in the proposed material (Gravel and Earth) obtain
area.
2.3.2 Existing Flora and Fauna in the Tank and Surrounding Habitats
2.3.2.1 Flora and Fauna in the Tank bund Area
Weedy, exotic and pioneer herbs, shrubs, climbers and trees, Chromolaena odorata
(Podisinnamaran), Cassia tora (Peti Tora), Vernonia cinerea (Monara Kudumbiya), Mimosa
pudica (Nidikumba), Flueggea leucopyrus (Heen Katu Pila), Sida acuta (Gas Bebila),
Xanthium indicum (Uru Kossa), Phyllanthus reticulatus (Kaila), Ocimum americanum (Heen
Tala), Tephrosia purpurea (Pila), Calotropis gigantea (Wara), Ricinus communis (Beheth
Endaru), Tribulus terrestris (Nerinchi), Bauhinia racemosa (Maila), Chloris barbata (Mayuru
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Tana), Cardiospermum halicacabum (Wel Penela), Cassia occidentalis (Peni Tora),
Panicum maximum (Rata Tana), Sida cordifolia (Wal Bevila), Aerva lanata (Pol Pala), Hyptis
suaveolens (Madurutala), Hibiscus micranthus (Bebila), Crotalaria verrucosa (Nil Andana
Hiriya), Lantana camara (Gandapana), Leucaena leucocephala (Ipil Ipil), Hibiscus vitifolius
(Maha Epala), Azadirachta indica (Kohomba), Commelina sp., Boerhavia diffusa (Pita Sudu
Pala), Cleome viscosa, Dipteracanthus prostratus (Nil Puruk), Evolvulus alsinoides (Visnu
Kranti), Mikania cordata (Wathu Palu), Pergularia daemia (Medahangu), Tephrosia villosa
(Bu Pila), Rauvolfia tetraphylla, Abutilon hirtum (Wal Anoda), Achyranthes aspera (Gas
Karal Heba), Tridax procumbens, Passiflora foetida, Indigofera sp., Coccinia grandis
(Kowakka), Clitoria ternatea (Katarodu), Morinda coreia (Ahu), Ipomoea marginata (Rasa
Tel Kola), Lannea coromandelica (Hik), Gomphrena celosioides are common in the
vegetation on the dam.
Holoptelea integrifolia (Goda Kirilla), Schleichera oleosa (Koon), Azadirachta indica
(Kohomba), Tamarindus indica (Siyabala), Mitragyna parvifolia (Helamba), Syzygium cumini
(Madan), Ficus racemosa (Attikka), Ceiba pentandra (Pulun), Ficus benghalensis (Maha
Nuga), Bauhinia racemosa (Maila), Lannea coromandelica (Hik), Lepisanthes tetraphylla
(Dambu), Cordia dichotoma (Lolu) are common inhabiting trees and Ziziphus oenoplia
(Heen Eraminiya), Vernonia zeylanica (Pupula), Croton aromaticus (Wel Keppetiya),
Argyreia populifolia (Giritilla), Toddalia asiatica (Kudu Miris), Diospyros montana, Pongamia
pinnata (Magul Karanda), Ficus mollis (Wal Aralu), Strychnos nux-vomica (Godakaduru),
Strychnos potatorum (Ingini) are other inhabiting plant species in the vegetation on the dam.
Figure 2:9: Vegetation on the Dam
Persicaria attenuata (Sudu Kimbul Wenna), Typha angustifolia (Hambu Pan), Nymphaea
pubescens (Olu), Cyperus ssp, Fimbristylis ssp, Colocasia esculenta (Gahala), Alocasia
macrorrhizos (Habarala), Lasia spinosa (Kohila), Pandanus amaryllifolius (Rampa), Mikania
cordata (Wathu Palu), Eichhornia crassipes (Japan Jabara) are common plant species
associate with water logged or marshy lands in the downstream area.
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Figure 2:10: Water logged or marshy lands in the downstream area of the tank bund
Sansevieria zeylanica (Niyanda), Bauhinia tomentosa (Kaha Petan), Ficus mollis (Wal
Aralu), Evolvulus alsinoides (Visnu Kranti), Flueggea leucopyrus (Heen Katu Pila),
Tephrosia purpurea (Pila), Ziziphus oenoplia (Heen Eraminiya), Morinda coreia (Ahu),
Azadirachta indica (Kohomba), Lannea coromandelica (Hik), Hibiscus micranthus (Bebila),
Pterospermum suberifolium (Welan), Hugonia mystax (Bu Getiya), Ventilago madraspatana
(Yakada Wel), Manilkara hexandra (Palu), Hyptis suaveolens (Madurutala), Chromolaena
odorata (Podisinnamaran), Lantana camara (Gandapana), Grewia orientalis (Wel Keliya),
Carissa spinarum (Heen Karamba), Benkara malabarica (Pudan), Aglaia elaeagnoidea,
Catunaregam spinosa (Kukurumanna), Derris scandens (Bo Kala Wel), Psilanthus
wightianus, Jatropha gossypiifolia, Hibiscus lobatus, Acacia pennata (Goda Hinguru),
Oxystelma esculentum (Usepale), Ehretia laevis, Reissantia indica, Mallotus repandus are
common inhabiting plant species in the rocky outcrop and associate vegetation
Figure 2:11: Rocky outcrop and associate vegetation
2.3.2.2 Flora and Fauna in the Tank and Irrigation Canals
Channa striata (Murrel), Etroplus suratensis (Pearl spot), Oreochromis niloticus (Tilapia),
Oreochromis mosambicus (Tilapia), Lepidocephalichthys thermalis (Common spiny loach),
Puntius bimaculatus (Redside barb), Rasbora microcephalus (Carverii Rasbora),
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Heteropneustes fossilis (Stinging catfish), Dawkinsia singhala (Filamented Barb) are
commonly observed fish species in the tank and irrigation canals. Fish species, Dawkinsia
singhala (Filamented Barb) is endemic to the country.
Water and water associate bird species, Ardea cinerea (Grey Heron), Ardeola grayii (Indian
Pond Heron), Anhinga melanogaster (Oriental Darter), Ardea purpurea (Purple Heron),
Casmerodius albus (Great Egret), Egretta garzetta (Little Egret), Mesophoyx intermedia
(Intermediate Egret), Anastomus oscitans (Asian Openbill), Mycteria leucocephala (Painted
Stork), Phalacrocorax niger (Little Cormorant), Phalacrocorax fuscicollis (Indian Cormorant),
Amaurornis phoenicurus (White-breasted Waterhen), Threskiornis melanocephalus (Black-
headed Ibis), Vanellus indicus (Red-wattled Lapwing), Halcyon smyrnensis (White-throated
Kingfisher), Alcedo atthis (Common Kingfisher), Chlidonias hybrid (Whiskered Tern), Sterna
albifrons (Little Tern), Actitis hypoleucos (Common Sandpiper), Dragonflies, Pantala
flavescens (Wandering Glider), Crocothemis servilia (Oriental Scarlet), Copera marginipes
(Yellow Featherleg), Ceriagrion coromandelianum (Yellow Waxtail), Brachythmis
contaminata (Asian Groundling), Rhyothemis variegata (Varigated Flutter), Amphibians,
Euphlyctis cyanophlyctis (Skipper frog), Fejervarya shyadrensis (Common paddy field frog)
are common associate fauna species with tank and irrigation canals.
Figure 2:12: Tank and Irrigation canals
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2.3.2.3 Rare, Threatened and Endemic Flora and Fauna in the Tank and
Surrounding Habitats
Vernonia zeylanica (Pupula), Argyreia populifolia (Giritilla) are recorded endemic plant
species and Strychnos nux-vomica (Godakaduru), Strychnos potatorum (Ingini) are
recorded nationally vulnerable (VU) plant species. Holoptelea integrifolia (Goda Kirilla),
Diospyros montana are recorded near threatened (NT) plant species.
Manilkara hexandra (Palu) and Psilanthus wightianus are recorded nationally vulnerable
(VU) plant species and Sansevieria zeylanica (Niyanda) is recorded near threatened (NT)
plant species in the rocky outcrop and associate vegetation.
Fish species, Dawkinsia singhala (Filamented Barb) was recorded in the irrigation canals
and streams of the project area and it is endemic to the country.
2.3.3 Ecological Signifcance of the Proposed Borrow Areas
2.3.3.1 Proposed borrow sites for obtaining gravel
Gravel for Angamuwa dam rehabilitation work to be obtained from nearby location and
secondary scrublands are the major existing vegetations/ habitats observed in and around
the proposed gravel obtain area. Dichrostachys cinerea (Andara), Flueggea leucopyrus
(Heen Katu Pila), Ocimum americanum (Heen Tala), Sida acuta (Gas Bebila), Hibiscus
micranthus (Bebila), Aerva lanata (Pol Pala), Ipomoea marginata (Rasa Tel Kola), Lantana
camara (Gandapana), Chromolaena odorata (Podisinnamaran), Tephrosia purpurea (Pila),
Cardiospermum halicacabum (Wel Penela), Hyptis suaveolens (Madurutala), Evolvulus
alsinoides (Visnu Kranti), Lannea coromandelica (Hik), Grewia helicterifolia (Bora
Daminiya), Cassia fistula (Ehela), Holoptelea integrifolia (Goda Kirilla), Ficus mollis (Wal
Aralu), Ziziphus oenoplia (Heen Eraminiya), Ventilago madraspatana (Yakada Wel), Grewia
orientalis (Wel Keliya), Carissa spinarum (Heen Karamba), Benkara malabarica (Pudan),
Catunaregam spinosa (Kukurumanna), Psilanthus wightianus, Acacia pennata (Goda
Hinguru), Vernonia zeylanica (Pupula), Strychnos potatorum (Ingini), Bauhinia tomentosa
(Kaha Petan), Ocimum gratissimum (Gas Tala), Cissus vitiginea, Premna latifolia, Dioscorea
tomentosa (Uyala), Diplocyclos palmatus (Pasengilla), Momordica charantia (Batu Karavila),
Ipomoea obscura (Tel Kola), Triumfetta pentandra (Epala), Coccinia grandis (Kowakka),
Tinospora cordifolia (Rasakinda), Tinospora sinensis (Bu Kinda), Drypetes sepiaria (Weera),
Allophylus cobbe (Kobbe), Cissus quadrangularis (Hirassa), Euphorbia antiquorum (Daluk),
Premna alstoni (Gal Kera), Ochna lanceolata (Bo Kera), Abrus precatorius (Olinda), Vitex
altissima (Milla), Curculigo orchioides (Heen Bin Tal) are observed common plant species in
the area.
Vernonia zeylanica (Pupula), Premna alstoni (Gal Kera) are recorded endemic plant species
and Psilanthus wightianus, Strychnos potatorum (Ingini), Tinospora cordifolia (Rasakinda)
are recorded nationally vulnerable (VU) plant species. Vitex altissima (Milla), Holoptelea
integrifolia (Goda Kirilla) are recorded nationally near threatened (NT) plant species. Plant
species, Lantana camara (Gandapana), Chromolaena odorata (Podisinnamaran) that
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observed during the study within the proposed gravel obtain area are consider as alien
invasive plant species.
With respect to fauna, two endemic species, one bird, Gallus lafayetii (Sri Lanka Junglefowl)
and one butterfly, Appias galane (Lesser albatross) were recorded within the area.
Figure 2:13: Proposed gravel borrow area
2.3.3.2 Proposed borrow sites for obtaining earth
Earth for the Angamuwa dam rehabilitation work will be obtained from tank bed in the
periphery of the tank. The area is seasonally inundated and Eichhornia crassipes (Japan
Jabara), Actinoscirpus grossus, Nymphaea nouchali (Manel), Nymphaea pubescens (Olu),
Ottelia alismoides, Pistia stratiotes (Diya Paradel), Panicum repens (Etora), Ludwigia
adscendens (Beru Diyanilla), Ceratophyllum demersum, Persicaria attenuata (Sudu Kimbul
Wenna), Cyperus ssp, Fimbristylis ssp, Marsilea minuta are inhabiting aquatic and semi
aquatic plant species in the area. No endemic plant species observed and Nymphaea
nouchali (Manel) is inhabiting nationally vulnerable (VU) plant species.
Figure 2:14: Proposed borrow site for earth extraction
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2.3.4 Migratory Paths
According to the information received from the villagers, there are no elephant paths
recorded in the area. However, the tank area is a preferable habitat for the migratory birds
which can be seen during the migratory season during October to April of every year.
2.4 Socioeconomic Environment
2.4.1 Local Administrative Units in the Project Area
The reservoir and its related other features are located in Rajanganaya Divisional
Secretariat of Anuradhapura District in North Central province. The specific details of the
local administrative units related to the project are mentioned below table 2.2:
Table 2.2: details of the local administrative units related to the project
Features of the irrigation
scheme
Relevant Grama
Niladhari divisions Relevant Villages
Head works and catchment area 448 Angamuwe Angamuwe Fishery Village
Command area
448-Angamuwe
449-Thumbullegama
450-Alivanguwe
451-Gamunupura
452-Track 9 and 10
453-Vijayapura
454-Track 12
455- Veheragala
456-Track 18
457-Adikaripura
458-Youth Farm
Angamuwe
Track 6 and 8
Thumbullegama
Akkara 50
Karuwalagaswewa
Lift irrigation area
Alivanguwe
Track 7
Siyambalagahagama
Gamunupura
Ingammaruwe
Temple Canal
Lunupitiya
Bogasela
Track 9 and 10
Track 11 and 12
Vijayapura
Banakoloniya
Veheragala
Track 13 and 14
Track 18 and 15
Adikaripura
Track 16 and 17
Namalsevanagama
Residential areas of farmers -do- -do-
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30
2.4.2 Land Use in Different Areas of the Irrigation Schemes
2.4.2.1 Catchment Area
The catchment area of this tank has not been encroached for any economic activities. The
entire extent of the catchment area gets filled with water at the FSL level and it is about 350
Acres. There are no encroachments in the catchment area of the tank.
2.4.2.2 Downstream of the Dam
The downstream of the Dam can be divided in to 2 areas for the ease of describing the land
use. The right side of the downstream area falls from end of the bund up to flat stone on
middle of the bund. The left side starts from the stone and runs up to the end of the bund
(See Sketch attached). The land area below the Dam on right side which belongs to ID has
been demarcated and it has not been encroached for any purpose.
The land belt below the dam on left side from the spill has been encroached for some socio-
economic purposes. This land belt is about 1,000 m long and 9 persons have encroached it
for several purposes. They have grown 39 coconut trees, 45 Banana bushes and also
constructed 2 shallow wells, one toilet pit and one poultry farm (with 10x 20 feet extent). The
schematic diagram to show the land use of the immediate dowanstream area of the tank
and the details of the 9 encroachers are shown in Annex 2.
2.4.2.3 Command Area
The total command area of the reservoir is 6,181 acres distributed among 22 Farmer
organizations (FOs). About 5,194 acres of this total command area falls under gravity
irrigation systems and the balance 987 acres is fed under a lift irrigation system. The land
use pattern of the gravity irrigation system is as follows:
The plot size ranges from 2 acres to 2.5 acres of each farmer family
About 20% of the total area is grown with perennial and semi-perennial crops such
as Banana and coconut.
The 80% of the command area is cultivated with 100% paddy in Maha seasons.
In Yala seasons about 75% of the area is grown with paddy and the balance is
with other seasonal field crops (OFCs)
Each farmer family in lift irrigation system has about 2 to 2.5 acre plot. Each plot has been
grown with perennial and semi-perennial crops such as coconut and Banana. Further details
of the land use pattern existing in gravity and lift irrigation systems are shown in the Annex
3.
2.4.3 Demographic Data Relevant to the Project Area
The population in the 11 GN areas of Rajanganaya DSDs is defined as project relevant
community. The community members in these 11 GN divisions have established 22 Farmer
Organizations (FOs). Some of the families in these 11 GN divisions are land owners under
the tank command and therefore, they are members of the 22 FOs. Nearly 50% of total
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
31
families in these GN divisions do not have land under Angamuwe irrigation scheme. The
99% populations residing in 11 GN areas are Sinhala ( except few Muslim families). The
details of population relevant to the proposed project are mentioned in Table 2.3.
Table 2.3: Details of Project Relevant Population
FO
GN
Total
Famili
es
Land owners Landless
No of
families Population
No of
families Population
Arunnalu –
Track 6
448 Angamuwe
449
Thumbullegama
433 84
912 550 1784 Track 6 BOP
Dimuthu 402 81
Track 7 BOP
Purasanda 120
Track 7 BOP
Suhada
450 Alivanguwe
451 Gamunupura
421 59
1452 574 2010
Track 7
Jayasri 568 92
Track 8
Mahasen 149
Track 8 BOP
Navajaya 115
Track 9
Nethsiri
452 Track 9,10
453 Vijayapura
518 180
2270 305 1218
Track 9 BOP
Pubudu 356 41
Track 10-
Ruhunu 98
Track 11
Ranketha 250
Track 12
Predeepalok
a 454 Track 12
455 Veheragala
438 179
2167 631 2261
Track 13 798 161
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32
Ekamuthu
Track 13
Pregathi 72
Track 14-
Vijaya 193
Track 15-
Jayamaha
457 Adikaripura
720 217
2630 54 214
Track 15
BOP
Ekamuthu
360
Track 15
BOP Udara 89
Track 15-
BOP Track
11, 15 456 Track 18
438 122
962 165 582
Track 18 Sri
Vijaya 151
Track 16
Youth Farm
458 Youth Farm
930 268
2260 342 1316
Track 17
Saraketha 320
Total 6022 3401 12653 2621 9385
The population of 9 families captured downstream reservation of the tank bund is 35. Only 5
families out of 9 are residing in the encroached land. The details of these families are given
in Annex 2.
2.4.4 Economic Activities of Project Related Population
The distribution of income generation activities among families in the project related 11 GN
divisions is given in Table 2.4.
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Table 2.4: Distribution of Income Generation Activities among Families in Project
Related Villages
Economic Activity Percentage of Families
Farming 55
Government employment 15
Private sector employment 20
Others (fishery, small business & foreign employment) 10
Source: FO leaders, GNs
The employments of the 9 families belong to encroached land of downstream of the dam
includes
Agriculture – 4 families
Growing ornamental flowers- 1family
Private sector- 1 family
Self employments- 2 families
Labor- 1 family
The details of the employments and the family size of the 9 families are given in Annex 2.
2.4.4.1 Yield and Income from Agriculture
a). Yield and Income from Agriculture
Paddy farming is the main source of income of the project relevant families in Angamuwa
irrigation scheme. According to the leaders of the farmer organizations and the 12 general
farmers interviewed (Annex 1) yield of the farmers in the scheme are fairly homogeneous.
Therefore, the information related to one farmer on yield and income of an acre cultivated
with paddy is mentioned below as representative case of the Padaviya irrigation scheme.
Yield – 2,442 kg per acre per season
Selling price and the gross income – 2,442kg * Rs 35/- = Rs 85,470/-
Average expenditure – Rs. 46,450/-
Net income – Rs 38,820/- per season ( Rs. 85,470 – Rs.46,450 )
Further details of the calculation of cost benefit are shown in Annex 4.
b). Cost Benefit Analysis of the Yield and Income from the entire irrigation
scheme
The team further worked out the cost benefit of the entire Angamuwa irrigation scheme
(Gravity Irrigation System) with the experience of the leaders of farmer organizations. The
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
34
details expressed by the farmer leaders are shown below table 2.5:
Table 2.5: Details Expressed by the Farmer Leaders
Yield Gross income Rs. Expenditure items Expenditure Rs.
Total land area =
5,194 acres, Yield of
an acre = 2,442 Kg ,
Total Yield = 2,442 *
5,194= 12,683,748
Kg
4,439,311,080
(12,683,748 kg * Rs.
35/-)
Total land area 5,194
acres, expenditure of
1 acre per season
Rs. 46,650/-,
Total expenditure of
the entire scheme
242,300,100 (5,194 *
46,650)
Note:
Total gross income – Rs. 4,439,311,080/=
Total expenditure – Rs. 242,300,100 /-
Net income – Rs 201,631,080/-
2.4.5 Other Water Uses
Three other direct and indirect water uses are reported in Angamuwa irrigation scheme
area. The details of these water uses are described below:
2.4.5.1 Fishing Activities
Fishing is a significant economic activity taking place in Angamuwe tank. The fishermen
have formed a separate organization and has registered it as a cooperative named
"Angamuwe Inland fishery cooperative Society". There are about 200 persons who have
registered as members in this Community-based Organization (CBO). They operate their
fishing activities from 4 boat landing sites and the members of the cooperative have 77
fishing boats. A fisherman is able to catch a quantity worth about Rs 1000 to 1,500/day. The
fish buyers from other areas around Rajanganaya/Tambuttegama visit to buy fish from
fishermen to sell in other villages in the area. The distribution of fishing boats among 4 boat
landing sites is shown below:
Angamuwe landing site - 30 boats
Navasirigama landing site - 30 Boats
Sirimapura ( Horombagama) Landing site – 12 Boats
5th Mile post Landing site - 5 boats
2.4.5.2 Bathing and Washing
There are about 150-200 families residing in Angamuwe Fishery village and Track 6 colony
used to go for bathing and washing in the reservoir
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2.4.5.3 Small Industries
About 21 rice mills are available in the project area and their performance is completely
depended on the agriculture in Angamuwa Irrigation system (6 large scale mills and 15
minor scale mills). Another about 10 mills use for rice processing and grain milling are also
available.
2.5 Current Environmental Issues of the Project Area
This subsection discusses the other issues pertaining to the area other than those that
would be caused by the project activities. The project activities may trigger some of them,
resulting in adverse impacts. Hence it is of paramount importance to mention such issues in
brief in order to lessen such impacts, if envisaged.
2.5.1 Physical Issues
There is no any major physical issue recorded in the project area.
2.5.2 Ecological Issues
There is no any major ecological issue recorded in the project area.
2.5.3 Socioeconomic Issues
The majority of the population in the project area can be defined as agriculture community of
which livelihood activities are heavily dependent on irrigation water and crop cultivation.
Therefore, most of the community members who were consulted expressed several issues
related to water and agriculture. The issues they expressed are summarized below:
Rapid fragmentation of land (both residential and irrigated). This has resulted in the
second and third generation families attempting to make their residences in the
irrigated lands plots
The cost of production under lift irrigation system is increasing rapidly
The fish fingerlings have not been provided for about 10 years and therefore, fish
population in the reservoir is very low at present
The small tanks located along the main canals are congested with water weeds
creating water management problems in main system (e.g. Thummulla tank,
Phalamaragahawewa).
Tendency of Farmers of Mahaweli System H located in the upstream of Angamuwa
Reservoir to expand their irrigated land towards the catchment area of Angamuwa.
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3. CHAPTER 03 : PROPOSED INTERVENTIONS
3.1 Proposed Engineering Interventions
The structural and operational issues of the dam, which are identified and observed during
the initial site visit are summarized in Table 3.1 and the photographic evidences for the
identified issues are given in Figure 3.1.
Table 3.1: Current issues in Angamuwa Tank Bund
a. Issues identified as per the ToR
Issue Intervention Construction methodology
1. Washed away
U/S slope and
rip rap
collapsed in
some areas
(Figure 3.1 A)
Improvements to tank
bund U/S slope and
bund crest (0+000 m to
1+775 m)
Removing the existing riprap and placed in
stockpiles in D/S identified areas for re-
measurement and re-use
Stripping topsoil to a depth of 100 mm
Benching along the tank bund slope by
machinery and backfilling including watering and
compaction
Furnishing, placing, spreading, watering and
compacting of gravel as wearing layer for dam
crest road and rip rap base.
Furnishing and placing a Geo textile along the
slope as directed
Furnishing and placing new graded rip rap as
directed
Turfing
2. Seepage areas
along the D/S
toes (Figure
3.1B)
Slope stabilization
and seepage control
Clearing and grubbing vegetation
Felling, logging uprooting trees on U/S and D/S
Reinstating cavities as directed
Removal of ant hills on D/S
Backfilling using suitable burrow material with
watering and compaction
Construction of toe drain and toe filter 0+150 m
to 0+200 m
3. Water
stagnating at
the dam
(Figure 3.1C)
Construction of pond
in D/S of tank bund
to collect toe drain
water at 0+067 m
and 0+310 m
Clearing and Grubbing of weeds
Stripping topsoil to remove loose soil
Borrow earth from identified borrow areas and
forming around the pond including watering and
compacting using manual labour
Furnishing and compacting rubble for U/S slope
of pond
Construction of spillway for proposed pond
Preparing and installation of measuring gauge
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for measuring pond water
4. Encroachments
at the dam
(Figure 3.1D)
Consult the
unauthorized settlers
and explain the need
of having a toe road
for the inspection
and safety of the
dam
Clear out the tank
reservation
Consultation process with all stakeholders
Formulation of action plan for relocation as per
law of the country
b. Issues identified during the initial site visit
Issue Intervention Construction methodology
5. The bund road
is with lots of
pot holes and
eroded places
(Figure 3.1F)
Construction of
access road from
0+000 m to 1+775
m
Construction of a
vehicle turning point
at the end of bund
road
Clearing and grubbing of weeds
Trimming and levelling the top surface of the
bund road by machinery
Furnishing, placing and compacting of the gravel
layer on the surface, including watering and
compacting by machinery
6. Structural
failures of the
spillway such as
failure of
abutments,
sliding of
sections (Figure
3.1G)
Construction of
curtain wall at U/S of
spill
Construction of coffer dam as required
Fixing dowels to existing rock surface as
directed
Fixing tor steel reinforcement net as directed
Placing and compacting cement concrete as
directed
7. Malfunction of
spillway radial
gates
Repairing radial
gates by removing
corroded parts of the
gates
Replace seals and
cables and related
attachments
Provision of motor
driven arrangements
for operation
In-situ repairs carried out for the gates –
removal of parts and replacing
Installation of motor driven system for the radial
gates
8. Leakage
through right
wing wall of
sluice and
Repairs in D/S of
sluice
Construction of
Gabion wall for slope
protection
Excavation for construction of gabion walls
Construction of gabion boxes
Transportation of rubble for gabions
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suspected areas
in U/S (Figure
3.1H)
Providing emergency
gates
Placement gabions and backfilling as needed
9. No bathing
steps and
inspection steps
Construction of
bathing steps at
0+100m,
0+500m,1+450 m,
and inspection steps
at 1+325 m of tank
bund
Displacement of rip rap as required
Construction of bathing steps and inspection
steps
Rearranging the rip rap as needed
10. Lack of security
facilities
Construction of
watcher hut and
storage area for the
field equipments at
the left end of
spillway
Site clearance
Material transportation for construction of the hut;
material storage
Construction of the hut
11. Anchoring
boats along the
U/S slope of
dam cause
bund erosion
and scouring
(Figure 3.1I)
Construction of boat
yard in Angamuwa
tank at 1+500 m of
tank bund
Transportation of material for the construction of
the boat yard
Removal of rip rap as required for construction of
the boat yard
Construction of boat yard
Rearrangement of the riprap and filling the bund
as needed
Figure 3:1.1A: Washed away U/S slope and rip rap collapsed in some areas
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Figure 3:2 B: Seepage areas along the
D/S toes
Figure 3:3 C: Water stagnating at the dam
Figure 3:4 D: Encroachments at the dam Figure 3:5 F: The bund road is with lots of
pot holes and eroded places
Figure 3:6 G: Structural failures of the
spillway such as failure of abutments,
Figure 3:7 H: Leakage through right wing
wall of sluice and suspected areas in U/S
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sliding of sections
Figure 3:8 I: Anchoring boats along the U/S
slope of dam cause bund erosion and
scouring
3.2 Proposed Borrowing Activities and the Identified Borrow Sites
The details of the borrow sites identified for the rehabilitation of Angamuwa tank are
described briefly in Error! Reference source not found. below.
Table 3.2: Location Details of the Identified Borrow Sites
Burrow Material Description GPS Location
Quarry site
The quarry site owned by N.S.K
Construction (Mr A.M.T. Adhikari) in
Singharagama Village within a Mahaweli
Land.
It is a “B” grade quarry site with GSMB and
CEA licenses
08o 16.431
080o 15.178
Gravel & Earth The site is located in the tank bed closer to
the bund and the area is inundated
08o 10.071
080o 13.500
Gravel Site 2 Existing site 08o 10.938
80o 12.809
Earth Site 2
The earth site is located in the tank bed
closer to the bund and the area is
inundated
08o 09.991
80o 13.474
The location maps for the identified borrow sites are given in the Annex 6a and 6b.
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3.3 Proposed Interventions that could Affect Neighboring Communities
Almost all the interventions will affect the neighboring communities in some manner;
however, they are not significant. The following interventions among what have been
proposed can be listed as interventions that could affect neighboring communities:
Material transport, stockpiling especially for graveling the bund road, rip rap
construction, correcting the slopes of the bund etc.
Providing toe filters, toe drain and the toe road along the toe area of the bund
Rehabilitating the bund (including construction of the rip rap) will prevent access to
the tank
3.4 Proposed Interventions that could affect the Natural Habitats
There is no significant impact anticipated, however removal of weedy shrubs and grasses
will disturb the associated faunal groups those who use such habitats as feeding, breeding
or nesting areas. Since there are enough similar habitats in the surrounding area, there will
be no or minor impact to such species.
The noise and dust created as a result of increase of vehicular traffic and heavy machinery
operations would temporary affect the existing fauna specially the avifauna.
The proposed rehabilitation work will take place within the Padaviya Sanctuary area and the
noise, vibration and hindrance to access paths will create a temporary disturbance to the
existing wild life in the area.
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4. CHAPTER 04 : PROJECT INDUCED IMPACTS
4.1 Identification of Project Induced Impacts
Note: The anticipated impacts described under this section are mainly for the construction
phase only. However, any impacts that are induced during operational stages (if any) are
also presented where applicable. The impacts are confined to negative impacts, as the
positive impacts as a result of improved dam safety and improved operational capacities of
Headworks are obvious and perceived.
Impacts were classified into three categories:
No: Environmental effects are perceived to have been no change at all.
Low: Environmental effects are not detectable or are so minor that they will neither
destabilize nor noticeably alter any important attribute of the resource.
Moderate: Environmental effects are sufficient to noticeably alter important
attributes of the resource, but not to destabilize them.
High: Environmental effects are clearly noticeable and are sufficient to destabilize
the resource.
Table 4.1 depicts the possible impacts together with their significance on each intervention
proposed.
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Table 4.1: Possible Impacts due to the Proposed Interventions and their Significance
Issues identified as per the ToR
Issue Intervention Anticipated Impacts Significance
1. Washed away
U/S slope and
rip rap
collapsed in
some areas
(Figure 3.1 A)
Improvements to tank
bund U/S slope and
bund crest (0+000 m
to 1+775 m)
Impact on Ecological Environment:
i. Damage to terrestrial and aquatic habitat
Clearing weedy shrubs, grasses and trimming the branches of the trees would
create habitat loss for the faunal species that use such habitats as their
feeding, breeding and nesting grounds. However, since there are enough
similar habitats available in the surrounding area, such species will get adapted
to the new conditions and hence the impact will be very low or none.
Low
ii. Threat of spreading of invasive species
The material to be extracted from the tank bed which is inundated during the
most of the time of the year. So there is a very less possibility of spreading
such species during material extraction.
Low
iii. Effect on fauna
There can be insignificant levels of noise and dust produced during material
transportation and construction work. In addition, due to heavy machinery there
may be temporary disturbances to the animals (especially migratory birds)
inhabiting the tank area.
However, the quantity of work will be less and hence the impact will be low.
Low
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Impact on Social Environment
i. Impact due to Material Transportation
Transportation routes of the borrow material (earth and Gravel) not associated
with the residential area and hence impact will be low or none
Low
ii. Impact due to lowering the water level in the tank
No negative impacts on the farming community if the work is carried out during
the dry season when the water level is lowest. Repair and rehabilitation work
will be undertaken only in Yala season.
No
Impacts on Physical Environment:
i. Hindrance to surface runoff
Borrow material once brought to the site has to be unloaded and stockpiled for
subsequent use. This might block the existing run – on and off paths which
may create erosion problems elsewhere.
However the quantity to be handled seems to be small, hence the impact may
not be significant.
Low
ii. Raw water quality of surface water bodies
Runoff through material borrow areas and unloading sites could lead to wash
off of soil particles to nearby water bodies such as canals, tanks streams etc.
resulting in temporary turbidity problems. However, the quantity to be handled
seems to be very low, hence adverse impacts anticipated would be
insignificant.
Low
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iii. Increasing the possibilities of erosion of the U/S/and D/S slopes
Exposed areas of the bund are susceptible to erosion. Low
iv. Increase in vehicular traffic during transport of construction materials
Material transport may result in air pollution through giving rise to elevated
levels of airborne dust. There are dwelling units along haulage routes and
elevated levels of airborne particulate matter can become a minor temporary
adverse impact during the construction period.
Low
v. Health and sanitation of worker’s camps and that of residents in the
adjoining areas
This impact is common for all the activities. The temporary camps, if not
managed properly, may create an unhealthy environment causing health
hazards to both workers and nearby residents. However, the number of
workers to be employed
Low
seems not many. Hence the impact is insignificant.
vi. Management of construction waste and excavated material and
wastewater
No significant quantities of construction waste are expected. In contrast, food
items even in small quantities may attract stray animals. However, the overall
impact is very low.
Low
vii. Generation of noise, vibration and dust affecting the social and
biological environment
Noise and vibration is very low due to the small-scale nature of construction
activities. Activities that would produce airborne dust are temporary and limited
Low
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to short durations and will be restricted to a small area.
viii. Impact of low water levels in the reservoirs during repairs
This impact could be very significant if the water levels are lowered suddenly.
However, the construction is planned to be carried out particularly during Yala
season where water level is expected to be lower compared to other seasons.
Low
2. Seepage areas
along the D/S
toes (Figure
3.1B)
Slope stabilization
and seepage
control
Impact on Ecological Environment:
i. Damage to aquatic habitat
Sediments, oil & grease and other chemicals that can be mixed into tank water
can pollute the aquatic habitat and will affect the fish and other aquatic faunal
species.
Low
Impact on Social Environment:
No negative impacts are envisaged on the farming community if the work is
carried out during the dry season.
No
Impacts on Physical Environment:
i. Hindrance to surface runoff
The borrow material once brought to the site has to be unloaded and stockpiled
for subsequent use. This might block the existing run–on and off paths which
may create erosion problems elsewhere.
However, the quantity to be handled seems to be small, hence the impact may
not be significant.
Low
ii. Raw water quality of surface water bodies
Runoff through material borrow areas and unloading sites could lead to wash
Low
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off of soil particles to nearby water bodies such as canals, tanks streams etc.
resulting in temporary turbidity problems. However, the quantity to be handled
seems to be very low, hence adverse impacts anticipated would be
insignificant.
iii. Increase in vehicular traffic during transport of construction materials
Material transport may result in air pollution through giving rise to elevated
levels of airborne dust. There are dwelling units along haulage routes and
elevated levels of airborne particulate matter can become a minor temporary
adverse impact during the construction period.
Low
iv. Health and sanitation of worker’s camps and that of residents in the
adjoining areas
This impact is common for all the activities. The temporary camps, if not
managed properly, may create an unhealthy environment causing health
hazards to both workers and nearby residents. However, the number of
workers to be employed seems not many. Hence the impact is insignificant.
Low
v. Management of construction waste and excavated material and
wastewater
No significant quantities of construction waste are expected. In contrast, food
items even in small quantities may attract stray animals. However, the overall
impact is very low.
Low
vi. Generation of noise, vibration and dust affecting the social and
biological environment
Noise and vibration is very low due to the small-scale nature of construction
activities. Activities that would produce airborne dust are temporary and limited
to short durations and will be restricted to a small area.
Low
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3. Water
stagnating at
the dam
(Figure 3.1C)
Construction of
pond in D/S of tank
bund to collect toe
drain water at
0+067 m and
0+310 m
Impact on Ecological Environment:
Positive impact on ecological environment as it will create better habitats for the
surrounding fauna.
Impact on Social Environment:
No negative impacts are envisaged No
Impacts on Physical Environment:
No negative impacts are envisaged No
4. Encroachments
at the dam
(Figure 3.1D)
Consult the
unauthorized
settlers and
explain the need of
having a toe road
for the inspection
and safety of the
dam
Clear out the tank
reservation
Impact on Ecological Environment:
No significant ecological impacts during construction is envisaged
Impact on SocialEnvironment:
No impact on the economic activities of the people as they have their own main
income sources and lands other than the encroached portion
No
Impacts on Physical Environment:
No negative impacts are envisaged No
c. Issues identified during the initial site visit
Issue Intervention Anticipated Impacts
5. The bund road
is with lots of
Construction of
access road from Impact on Ecological Environment:
i. Damage to terrestrial and aquatic habitat
Low
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pot holes and
eroded places
(Figure 3.1F)
0+000 m to 1+775
m
Construction of a
vehicle turning
point at the end of
bund road
Clearing weedy shrubs, grasses and trimming the branches of the trees
would create habitat loss for the faunal species that use such habitats as
their feeding, breeding and nesting grounds. However, since there are
enough similar habitats available in the surrounding area, such species will
get adapted to the new conditions and hence the impact will be very low or
none.
ii. Threat of spreading of invasive species
The material to be extracted from the tank bed which is inundated during the
most of the time of the year. So there is a very less possibility of spreading
such species during material extraction.
Low
iv. Effect on fauna
There can be insignificant levels of noise and dust produced during material
transportation and construction work. In addition, due to heavy machinery there
may be temporary disturbances to the animals (especially migratory birds)
inhabiting the tank area.
However, the quantity of work will be less and hence the impact will be low.
Low
ii. Effect on aquatic habitat
Sediments, oil & grease and other chemicals that can be mixed into tank water
can pollute the aquatic habitat and will affect the fish and other aquatic faunal
species.
Low
Impact on Social Environment
i. Impact due to Material Transportation
Transportation routes of the borrow material (earth and Gravel) not associated
with the residential area and hence impact will be low or none
Low
ii. Impact due to blockage of access
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
50
The bund road is not used as an access to residence or it is not linked with
other settlement. However, there will be a temporary disturbance to the people
those who access tank for their domestic purposes.
Impacts on Physical Environment:
i. Hindrance to surface runoff
Borrow material once brought to the site has to be unloaded and stockpiled for
subsequent use. This might block the existing run – on and off paths which
may create erosion problems elsewhere.
However the quantity to be handled seems to be small, hence the impact may
not be significant.
Low
ii. Raw water quality of surface water bodies
Runoff through material borrow areas and unloading sites could lead to wash
off of soil particles to nearby water bodies such as canals, tanks streams etc.
resulting in temporary turbidity problems. However, the quantity to be handled
seems to be very low, hence adverse impacts anticipated would be
insignificant.
Low
iii. Increasing the possibilities of erosion of the U/S/and D/S slopes
Exposed areas of the bund are susceptible to erosion. Low
iv. Increase in vehicular traffic during transport of construction materials
Material transport may result in air pollution through giving rise to elevated
levels of airborne dust. There are dwelling units along haulage routes and
elevated levels of airborne particulate matter can become a minor temporary
adverse impact during the construction period.
Low
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
51
v. Health and sanitation of worker’s camps and that of residents in the
adjoining areas
This impact is common for all the activities. The temporary camps, if not
managed properly, may create an unhealthy environment causing health
hazards to both workers and nearby residents. However, the number of
workers to be employed seems not many. Hence the impact is insignificant.
Low
vi. Management of construction waste and excavated material and
wastewater
No significant quantities of construction waste are expected. In contrast, food
items even in small quantities may attract stray animals. However, the overall
impact is very low.
Low
vii. Generation of noise, vibration and dust affecting the social and
biological environment
Noise and vibration is very low due to the small-scale nature of construction
activities. Activities that would produce airborne dust are temporary and limited
to short durations and will be restricted to a small area.
Low
6. Structural
failures of the
spillway such as
failure of
abutments,
sliding of
sections (Figure
3.1G)
Construction of
curtain wall at U/S
of spill
Impact on Ecological Environment:
No significant ecological impact during the construction No
Impact on Social Environment:
No significant negative impacts during the construction are envisaged as the
construction will be carried out during dry season and using coffer damning
No
Impact on Physical Environment:
Increasing the possibilities of erosion of U/S/and D/S slopes
Low
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
52
Excavated and exposed areas of the bund are susceptible to erosion
In addition to those, general impacts such as generation of construction waste,
excavated material, wastewater, generation of noise and vibration and dust
which affect the social and biological environment could be envisaged. Since
the amount of work that has to be carried out is small, the impact is insignificant
7. Malfunction of
spillway radial
gates
Repairing radial
gates by removing
corroded parts of
the gates
Replace seals and
cables and related
attachments
Provision of motor
driven
arrangements for
operation
Impact on Ecological Environment:
No significant ecological impact during the construction No
Impact on Social Environment:
No significant negative impacts during the construction are envisaged.
No
Impact on Physical Environment:
Increasing the possibilities of erosion of U/S/and D/S slopes
Excavated and exposed areas of the bund are susceptible to erosion
In addition to those, general impacts such as generation of construction waste,
excavated material, wastewater, generation of noise and vibration and dust
which affect the social and biological environment could be envisaged. Since
the amount of work that has to be carried out is small, the impact is insignificant
Low
8. Leakage
through right
wing wall of
sluice and
suspected areas
in U/S (Figure
Repairs in D/S of
sluice
Construction of
Gabion wall for
slope protection
Providing
Impact on Ecological Environment:
No significant ecological impacts during construction is envisaged
No
Impact on Social Environment:
No significant negative impacts during the construction are envisaged.
No
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
53
3.1H) emergency gates Impact on Physical Environment:
No significant impacts during the construction are envisaged No
9. No bathing
steps and
inspection steps
Construction of
bathing steps at
0+100m,
0+500m,1+450 m,
and inspection
steps at 1+325 m
of tank bund
Impact on Ecological Environment:
No significant ecological impacts during construction is envisaged
No
Impact on Social Environment:
No significant negative impacts during the construction are envisaged.
No
Impact on Physical Environment:
No significant impacts during the construction are envisaged. However, general
impacts such as generation of construction waste, excavated material,
wastewater, generation of noise and vibration and dust which affect the social
and biological environment could be envisaged. Since the amount of work that
has to be carried out is small, the impact is insignificant.
Low
10. Lack of security
facilities
Construction of
watcher hut and
storage area for
the field
equipments at the
left end of spillway
Impact on Ecological Environment:
No significant ecological impacts during construction is envisaged
No
Impact on Social Environment:
No significant negative impacts during the construction are envisaged.
No
Impact on Physical Environment:
No significant impacts during the construction are envisaged. However, general
impacts such as generation of construction waste, excavated material,
wastewater, generation of noise and vibration and dust which affect the social
and biological environment could be envisaged. Since the amount of work that
Low
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
54
has to be carried out is small, the impact is insignificant.
11. Anchoring
boats along the
U/S slope of
dam cause
bund erosion
and scouring
(Figure 3.1I)
Construction of
boat yard in
Angamuwa tank at
1+500 m of tank
bund
Impact on Ecological Environment:
i. Effect on aquatic habitat
Sediments, oil & grease and other chemicals that can be mixed into tank water
can pollute the aquatic habitat and will affect the fish and other aquatic faunal
species.
Low
Impact on Ecological Environment:
There can be temporary impact to the fishermen, but there are enough of other
areas to carry out their activities and hence the impact will be low/none
No
Impact on Physical Environment:
Increasing the possibilities of erosion of U/S/and D/S slopes
Excavated and exposed areas of the bund are susceptible to erosion
Low
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
55
4.2 Quantification of their Significance
Determining the significance of impacts places value on impact magnitude. It relates to the
importance society places on the resources affected, the importance of the impact to system
stability and sustainability.
Quantification of impact magnitude in this study has been objective-based backed by prior
experience of the team of consultants, rather than applying numerical and/or scientific
principles and theories. Once the impact magnitude was determined based on the proposed
construction methodology for each intervention, each expert has decided on the significance
of the impacts based on their area of expertise. Significant impacts will be the focus of
mitigation measures and subsequent monitoring, as outlined in the report.
Factors that have been considered in determining of impact significance include
(but are not limited to):
Area of Influence: Impact significance is often directly related to the size of the area
affected.
Amount of Resource Usage: The greater the amount of resource usage, the more
significant the impact.
Status of Resources: Impacts due to usage of limited resources are usually
considered more significant than impacts to common or abundant resources.
Persistence of Impacts: Permanent or long-term changes are usually more
significant than temporary ones. The ability of the resource to recover, after the
activities are complete, is related to this effect.
Sensitivity of Resources: Impacts to sensitive resources are usually more
significant than impacts to those that are relatively resilient to impacts.
Regulatory Status: Impacts to resources that are protected (e.g., endangered
species, air quality, cultural resources, water quality) typically are considered more
significant than impacts to those without regulatory status.
Societal Value: Some resources have societal value, such as archaeological,
cultural and sacred sites, traditional practices, and recreational areas.
Hence, quantification of impacts was done based on the above-mentioned criteria
only for the impacts that are perceived to be either moderate or high.
All the impacts identified for the proposed interventions are either low or none and hence the
quantification of such impacts are not required for Angamuwa Dam rehabilitation work.
Environmental Assessment for Rehabilitation of Padaviya Tank Draft Final Report
56
5. CHAPTER 05 : ENVIRONMENTAL MANAGEMENT PLAN
5.1 General Overview
The purpose of this Environmental Management Plan (EMP) is to manage the anticipated
on and off-site environmental impacts due to the interventions proposed to remedy identified
issues of the dam. Therefore, it is necessary to first scan the issues that have arisen to
compromise the safety and operational efficiency of the Angamuwa Dam. The following
issues and their mitigation measures were identified and presented in the EMP.
5.2 Identification of Impacts and their Mitigations
This section summarizes the mitigation measures to be implemented for the identified
environmental impacts that can potentially occur predominantly during the construction
phase of the proposed interventions (Table 5.1). This table indicates only the ones that need
mitigation measures and those that are not listed would not require any mitigation
measures.
The DSWRPP has a strong focus on proper environmental management. Therefore, the
focus of environmental management of the project has not been limited to managing those
impacts arising due to the proposed interventions but also to improve adverse
environmental conditions that will prevail during rehabilitation work by applying proper
mitigation strategies.
As a part of the EMP, appropriate institutional arrangements to implement the proposed
measures and clearances and/or approvals needed by the project prior to its implementation
have been proposed after discussing with the responsible authorities 9Table 5.2). For each
proposed intervention, the EMP defines the technical content, roles and responsibilities of
stakeholders, schedule of implementation and methods of monitoring etc.
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
57
Table 5.1: Proposed Mitigatory Measures for the Identified Impacts
Issues identified as per the ToR
Issue Intervention Anticipated Impacts Proposed Mitigation
1. Washed away
U/S slope and
rip rap
collapsed in
some areas
(Figure 3.1 A)
Improvements to tank
bund U/S slope and
bund crest (0+000 m
to 1+775 m)
Impact on Ecological Environment:
i. Damage to terrestrial and aquatic habitat
Clearing weedy shrubs, grasses and trimming the branches
of the trees would create habitat loss for the faunal species
that use such habitats as their feeding, breeding and nesting
grounds. However, since there are enough similar habitats
available in the surrounding area, such species will get
adapted to the new conditions and hence the impact will be
very low or none.
The easily decomposable
vegetation could either be
utilized as a soil conditioner
after drying or be composted in
a proper manner. Large
vegetation parts could be sold
or else be used as firewood.
The contractor is responsible
for proper management of all
vegetative parts that are to be
uprooted.
The project area must be
covered or fenced properly to
avoid disturbances to the
surrounding habitats including
the tank water
ii. Threat of spreading of invasive species
The material to be extracted from the tank bed which is
inundated during the most of the time of the year. So there is a
very less possibility of spreading such species during material
extraction.
Close monitoring of
transportation, storage of
borrowing material for the
spread of any invasive species
must be done. Vehicles should
be covered during
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
58
transportation.
Borrow material to be brought
from properly identified borrow
pits and quarry sites with
proper licenses
Washing the vehicles
periodically to prevent carrying
any invasive species
All the gravel transporting
vehicles must be covered
during transportation. Frequent
checks for invasive species
must be undertaken
iii. Effect on fauna
There can be insignificant levels of noise and dust produced
during material transportation and construction work. In
addition, due to heavy machinery there may be temporary
disturbances to the animals (especially migratory birds)
inhabiting the tank area.
However, the quantity of work will be less and hence the impact
will be low.
The construction area of the
tank should be temporary
barricaded to restrict the
movement of animals into the
construction area.
The other habitat areas in the
vicinity of the tank should not
be disturbed so that fauna
inhabiting the area will move to
such areas.
Impact on Social Environment
i. Impact due to Material Transportation
Transportation routes of the borrow material (earth and Gravel)
The required mitigation is
mentioned below (see Impact
on Physical environment).
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
59
not associated with the residential area and hence impact will
be low or none
ii. Impact due to lowering the water level in the tank
No negative impacts on the farming community if the work is
carried out during the dry season when the water level is
lowest. Repair and rehabilitation work will be undertaken only in
Yala season.
No mitigation is required
Impacts on Physical Environment:
i. Hindrance to surface runoff
Borrow material once brought to the site has to be unloaded
and stockpiled for subsequent use. This might block the
existing run – on and off paths which may create erosion
problems elsewhere.
However the quantity to be handled seems to be small, hence
the impact may not be significant.
Surface run on and off paths
should not be selected for
material unloading areas.
Erosion of material heaps can
be minimized by covering
them during rainy seasons.
Avoid stockpiling of materials
close to water bodies; Stripped
materials should not be stored
where natural drainage will be
disrupted. There are several
areas identified, especially the
eastern part of the bund
(downstream side) as suitable
for stockpiling and for
machinery, tools and vehicular
parking spaces. Use of these
areas for such purposes might
not pose negative impacts on
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
60
residential and cultivated areas
and also to the water body.
ii. Raw water quality of surface water bodies
Runoff through material borrow areas and unloading sites could
lead to wash off of soil particles to nearby water bodies such as
canals, tanks streams etc. resulting in temporary turbidity
problems. However, the quantity to be handled seems to be
very low, hence adverse impacts anticipated would be
insignificant.
Surface run on and off paths
should not be selected for
material unloading areas.
Erosion of material heaps can
be minimized by covering
them during rainy seasons.
Avoid stockpiling of materials
close to water bodies; Stripped
materials should not be stored
where natural drainage will be
disrupted. There are several
areas identified, especially the
eastern part of the bund
(downstream side) as suitable
for stockpiling and for
machinery, tools and vehicular
parking spaces. Use of these
areas for such purposes might
not pose negative impacts on
residential and cultivated areas
and also to the water body.
iii. Increasing the possibilities of erosion of the U/S/and
D/S slopes
Exposed areas of the bund
slopes will be covered with
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
61
Exposed areas of the bund are susceptible to erosion. turfing material as soon as
possible to prevent any
erosion.
All the measures mentioned
above are valid for this impact
as well.
iv. Increase in vehicular traffic during transport of
construction materials
Material transport may result in air pollution through giving rise
to elevated levels of airborne dust. There are dwelling units
along haulage routes and elevated levels of airborne particulate
matter can become a minor temporary adverse impact during
the construction period.
Restrictions on the
transportation activities:
a. Maximum axial loads
and speed limits for
vehicles moving on the
bund will be imposed
b. Time limits for carrying
out transportation
activities to control
excessive noise
generation and to
prevent nuisance to
neighbouring
communities (6.00 am –
6.00 pm)
Dust emission due to transport
operations should be
controlled by wet spraying and
tarpaulin covering in
mandatory on trucks/lorries
which are used for transporting
materials particularly in built up
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
62
areas.
Transport, loading and
unloading of materials should
be carried out in such a way as
not to cause nuisance to the
people by way of noise,
vibration of dust. Care must be
taken while unloading material
on the bund so as the material
may be not rolled down on
either side of U/S and D/S
slopes causing damages
v. Health and sanitation of worker’s camps and that of
residents in the adjoining areas
This impact is common for all the activities. The temporary
camps, if not managed properly, may create an unhealthy
environment causing health hazards to both workers and
nearby residents. However, the number of workers to be
employed seems not many. Hence the impact is insignificant.
Conditions of worker camps to
be checked by the Public
Health Officer in charge of the
relevant area on a regular
basis.
All food leftovers and organic
garbage should be disposed of
in a proper manner so that it
will not attract stray and wild
animals. Solid waste should
not be burnt in the open air
within or outside the proposed
site.
Proper sanitation facilities
should be provided on-site for
the workforce. Ideally, this can
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
63
be a pit latrine in which the pit
is located above the ground
water table. Covering the
deposit (with earth or sawdust)
is necessary to prevent smells
and to discourage flies.
This measure is common for
all the interventions and
therefore applicable for the
whole project period.
vi. Management of construction waste and excavated
material and wastewater
No significant quantities of construction waste are expected. In
contrast, food items even in small quantities may attract stray
animals. However, the overall impact is very low.
Construction waste shall be
collected regularly and
disposed of periodically in an
environmentally safe and
nuisance free manner.
Wastewater will be disposed,
by way of a pit latrine/soakage
arrangement. This measure
too will be common and valid
for the entire construction
period.
vii. Generation of noise, vibration and dust affecting the
social and biological environment
Noise and vibration is very low due to the small-scale nature of
construction activities. Activities that would produce airborne
dust are temporary and limited to short durations and will be
restricted to a small area.
Hydraulically driven machinery
is preferred over Pneumatic
machinery to minimize
vibrations
No high noise generating
machinery is encouraged.
Extreme precautions need to
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
64
be taken on vibration levels as
it could affect the core of the
bund. Watering may be
necessary if any activity
generates dust particles.
Excessive noise and vibration
at the quarry site has to be
controlled. Implement the
conditions such as noise
monitoring and other
recommendations stipulated in
the permit; Obtain approval
from the Local Authority and
Divisional Secretary and
Controller of Explosives (for
quarry sites only) and CEA.
All raw materials (sand,
rubble, metal, etc.) should be
stored in covered areas to
ensure protection from dust
emissions and such materials
should be handled in an
environmentally friendly and
nuisance free manner.
These measures will also be
the same for all other
interventions.
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
65
viii. Impact of low water levels in the reservoirs during
repairs
This impact could be very significant if the water levels are
lowered suddenly. However, the construction is planned to be
carried out particularly during Yala season where water level is
expected to be lower compared to other seasons.
No mitigation is required as the
lowering water level will not
adversely affect the bund or
any other related structures.
2. Seepage areas
along the D/S
toes (Figure
3.1B)
Slope stabilization
and seepage
control
Impact on Ecological Environment:
i. Damage to aquatic habitat
Sediments, oil & grease and other chemicals that can be mixed
into tank water can pollute the aquatic habitat and will affect the
fish and other aquatic faunal species.
The construction area of the
tank should be temporary
barricaded
Impact on Social Environment:
No negative impacts are envisaged on the farming community if
the work is carried out during the dry season.
No mitigation is required
Impacts on Physical Environment:
i. Hindrance to surface runoff
The borrow material once brought to the site has to be
unloaded and stockpiled for subsequent use. This might block
the existing run–on and off paths which may create erosion
problems elsewhere.
However, the quantity to be handled seems to be small, hence
the impact may not be significant.
Same as above described for
the similar impact
ii. Raw water quality of surface water bodies Same as above described for
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
66
Runoff through material borrow areas and unloading sites could
lead to wash off of soil particles to nearby water bodies such as
canals, tanks streams etc. resulting in temporary turbidity
problems. However, the quantity to be handled seems to be
very low, hence adverse impacts anticipated would be
insignificant.
the similar impact
iii. Increase in vehicular traffic during transport of
construction materials
Material transport may result in air pollution through giving rise
to elevated levels of airborne dust. There are dwelling units
along haulage routes and elevated levels of airborne particulate
matter can become a minor temporary adverse impact during
the construction period.
Same as above described for
the similar impact
iv. Health and sanitation of worker’s camps and that of
residents in the adjoining areas
This impact is common for all the activities. The temporary
camps, if not managed properly, may create an unhealthy
environment causing health hazards to both workers and
nearby residents. However, the number of workers to be
employed seems not many. Hence the impact is insignificant.
Same as above described for
the similar impact
v. Management of construction waste and excavated
material and wastewater
No significant quantities of construction waste are expected. In
contrast, food items even in small quantities may attract stray
animals. However, the overall impact is very low.
Same as above described for
the similar impact
vi. Generation of noise, vibration and dust affecting the Same as above described for
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
67
social and biological environment
Noise and vibration is very low due to the small-scale nature of
construction activities. Activities that would produce airborne
dust are temporary and limited to short durations and will be
restricted to a small area.
the similar impact
3. Water
stagnating at
the dam
(Figure 3.1C)
Construction of
pond in D/S of tank
bund to collect toe
drain water at
0+067 m and
0+310 m
Impact on Ecological Environment:
Positive impact on ecological environment as it will create better
habitats for the surrounding fauna.
No mitigation required
Impact on Social Environment:
No negative impacts are envisaged
No mitigation is required
Impacts on Physical Environment:
No negative impacts are envisaged
No mitigation is required
4. Encroachments
at the dam
(Figure 3.1D)
Consult the
unauthorized
settlers and
explain the need of
having a toe road
for the inspection
and safety of the
dam
Clear out the tank
Impact on Ecological Environment:
No significant ecological impacts during construction is
envisaged
No mitigation is required
Impact on SocialEnvironment:
No impact on the economic activities of the people as they
have their own main income sources and lands other than the
encroached portion
No mitigation is required
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
68
reservation Impacts on Physical Environment:
No negative impacts are envisaged
No mitigation is required
d. Issues identified during the initial site visit
Issue Intervention Anticipated Impacts
5. The bund road
is with lots of
pot holes and
eroded places
(Figure 3.1F)
Construction of
access road from
0+000 m to 1+775
m
Construction of a
vehicle turning
point at the end of
bund road
Impact on Ecological Environment:
i. Damage to terrestrial and aquatic habitat
Clearing weedy shrubs, grasses and trimming the branches of
the trees would create habitat loss for the faunal species that
use such habitats as their feeding, breeding and nesting
grounds. However, since there are enough similar habitats
available in the surrounding area, such species will get
adapted to the new conditions and hence the impact will be
very low or none.
Same as above described for
the similar impact
ii. Threat of spreading of invasive species
The material to be extracted from the tank bed which is
inundated during the most of the time of the year. So there is a
very less possibility of spreading such species during material
extraction.
Same as above described for
the similar impact
iv. Effect on fauna
There can be insignificant levels of noise and dust produced
during material transportation and construction work. In addition,
due to heavy machinery there may be temporary disturbances to
the animals (especially migratory birds) inhabiting the tank area.
Same as above described for
the similar impact
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
69
However, the quantity of work will be less and hence the impact
will be low.
ii. Effect on aquatic habitat
Sediments, oil & grease and other chemicals that can be mixed
into tank water can pollute the aquatic habitat and will affect the
fish and other aquatic faunal species.
Same as above described for
the similar impact
Impact on Social Environment
iii. Impact due to Material Transportation
Transportation routes of the borrow material (earth and Gravel)
not associated with the residential area and hence impact will be
low or none
Same as above described for
the similar impact
iv. Impact due to blockage of access
The bund road is not used as an access to residence or it is not
linked with other settlement. However, there will be a temporary
disturbance to the people those who access tank for their
domestic purposes.
No mitigation is required
Impacts on Physical Environment:
i. Hindrance to surface runoff
Borrow material once brought to the site has to be unloaded and
stockpiled for subsequent use. This might block the existing run
– on and off paths which may create erosion problems
elsewhere.
However the quantity to be handled seems to be small, hence
the impact may not be significant.
Same as above described for
the similar impact
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
70
ii. Raw water quality of surface water bodies
Runoff through material borrow areas and unloading sites could
lead to wash off of soil particles to nearby water bodies such as
canals, tanks streams etc. resulting in temporary turbidity
problems. However, the quantity to be handled seems to be very
low, hence adverse impacts anticipated would be insignificant.
Same as above described for
the similar impact
iii. Increasing the possibilities of erosion of the U/S/and D/S
slopes
Exposed areas of the bund are susceptible to erosion.
Same as above described for
the similar impact
iv. Increase in vehicular traffic during transport of
construction materials
Material transport may result in air pollution through giving rise
to elevated levels of airborne dust. There are dwelling units
along haulage routes and elevated levels of airborne particulate
matter can become a minor temporary adverse impact during
the construction period.
Same as above described for
the similar impact
v. Health and sanitation of worker’s camps and that of
residents in the adjoining areas
This impact is common for all the activities. The temporary
camps, if not managed properly, may create an unhealthy
environment causing health hazards to both workers and nearby
residents. However, the number of workers to be employed
seems not many. Hence the impact is insignificant.
Same as above described for
the similar impact
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
71
vi. Management of construction waste and excavated
material and wastewater
No significant quantities of construction waste are expected. In
contrast, food items even in small quantities may attract stray
animals. However, the overall impact is very low.
Same as above described for
the similar impact
vii. Generation of noise, vibration and dust affecting the
social and biological environment
Noise and vibration is very low due to the small-scale nature of
construction activities. Activities that would produce airborne
dust are temporary and limited to short durations and will be
restricted to a small area.
Same as above described for
the similar impact
6. Structural
failures of the
spillway such as
failure of
abutments,
sliding of
sections (Figure
3.1G)
Construction of
curtain wall at U/S
of spill
Impact on Ecological Environment:
No significant ecological impact during the construction
No mitigation is required
Impact on Social Environment:
No significant negative impacts during the construction are
envisaged as the construction will be carried out during dry
season and using coffer damning
No mitigation is required
Impact on Physical Environment:
Increasing the possibilities of erosion of U/S/and D/S slopes
Excavated and exposed areas of the bund are susceptible to
erosion
In addition to those, general impacts such as generation of
construction waste, excavated material, wastewater, generation
of noise and vibration and dust which affect the social and
Same as above described for
the similar impact
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
72
biological environment could be envisaged. Since the amount of
work that has to be carried out is small, the impact is
insignificant
7. Malfunction of
spillway radial
gates
Repairing radial
gates by removing
corroded parts of
the gates
Replace seals and
cables and related
attachments
Provision of motor
driven
arrangements for
operation
Impact on Ecological Environment:
No significant ecological impact during the construction
No mitigation is required
Impact on Social Environment:
No significant negative impacts during the construction are
envisaged.
No mitigation is required
Impact on Physical Environment:
Increasing the possibilities of erosion of U/S/and D/S slopes
Excavated and exposed areas of the bund are susceptible to
erosion
In addition to those, general impacts such as generation of
construction waste, excavated material, wastewater, generation
of noise and vibration and dust which affect the social and
biological environment could be envisaged. Since the amount of
work that has to be carried out is small, the impact is
insignificant
Same as above described for
the similar impact
8. Leakage
through right
wing wall of
sluice and
suspected areas
in U/S (Figure
3.1H)
Repairs in D/S of
sluice
Construction of
Gabion wall for
slope protection
Providing
Impact on Ecological Environment:
No significant ecological impacts during construction is
envisaged
No mitigation is required
Impact on Social Environment:
No significant negative impacts during the construction are
No mitigation is required
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
73
emergency gates envisaged.
Impact on Physical Environment:
No significant impacts during the construction are envisaged
No mitigation is required
9. No bathing
steps and
inspection steps
Construction of
bathing steps at
0+100m,
0+500m,1+450 m,
and inspection
steps at 1+325 m
of tank bund
Impact on Ecological Environment:
No significant ecological impacts during construction is
envisaged
No mitigation is required
Impact on Social Environment:
No significant negative impacts during the construction are
envisaged.
No mitigation is required
Impact on Physical Environment:
No significant impacts during the construction are envisaged.
However, general impacts such as generation of construction
waste, excavated material, wastewater, generation of noise and
vibration and dust which affect the social and biological
environment could be envisaged. Since the amount of work that
has to be carried out is small, the impact is insignificant.
Same as above described for
the similar impact
10. Lack of security
facilities
Construction of
watcher hut and
storage area for
the field
equipments at the
left end of spillway
Impact on Ecological Environment:
No significant ecological impacts during construction is
envisaged
No mitigation is required
Impact on Social Environment:
No significant negative impacts during the construction are
No mitigation is required
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
74
envisaged.
Impact on Physical Environment:
No significant impacts during the construction are envisaged.
However, general impacts such as generation of construction
waste, excavated material, wastewater, generation of noise and
vibration and dust which affect the social and biological
environment could be envisaged. Since the amount of work that
has to be carried out is small, the impact is insignificant.
Same as above described for
the similar impact
11. Anchoring
boats along the
U/S slope of
dam cause
bund erosion
and scouring
(Figure 3.1I)
Construction of
boat yard in
Angamuwa tank at
1+500 m of tank
bund
Impact on Ecological Environment:
i. Effect on aquatic habitat
Sediments, oil & grease and other chemicals that can be mixed
into tank water can pollute the aquatic habitat and will affect the
fish and other aquatic faunal species.
Same as above described for
the similar impact
Impact on Social Environment:
There can be temporary impact to the fishermen, but there are
enough of other areas to carry out their activities and hence the
impact will be low/none
No mitigation is required
Impact on Physical Environment:
Increasing the possibilities of erosion of U/S/and D/S slopes
Excavated and exposed areas of the bund are susceptible to
erosion
Same as above described for
the similar impact
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
75
5.3 Implementation Schedules of Proposed Mitigation
The specific mitigation measures given in the Error! Reference source not found. should be
mplemented by the contractor when each and every intervention is done. In addition to the
specific measures, the contractor must adhere to the civil engineering best practices as
practical as possible. Most of such practices are described in ICTAD specifications and the
contractor is recommended to follow them when appropriate.
Time of the implementation of mitigation measures should be decided by the contractor and
they should be informed to the Project Engineer in advance and his approval should be
obtained. The key performing indicators (KPIs) for every mitigation carried out must be
worked out and should be informed to the PM for subsequent checks and balances. Once
the KPIs are accepted such indicators should be monitored by the PM to ensure that
measures are taken to minimize or avoid environmental degradation or pollution that is very
likely due to the said project.
It should be necessary that all mitigation measures mentioned in the report be implemented
by the contractor and for such implementation budgetary allocation must be set aside. It has
to be done during the bidding process and the allocation so kept must be utilized by the
contractor in an efficient manner.
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76
5.4 Formal Clearances and Approval Needed
Error! Reference source not found. gives the details of the clearances and approvals for the project.
Table 5.2: Formal Clearances and Approval Needed
No
Issues / Activity /
Intervention needing the
permit or approval
The Reasons for the Approval (Law,
Act or enforcements etc.)
Authority from which
permit or approval or
Clarence is required
Prior Approval and Acts
1
National environmental
protection and quality
regulations under
Extraordinary gazette
notification No. 1534/18 and
No. 1533/16 of 2008 under
NEA section 32 & 23A, 23B
Environmental Protection Licenses (EPL)
from CEA, in particular prescribed
activities in gazette No. 1533/16 of 2008
(i.e., Concrete batching plants, treatment
plants, sewerage networks, mechanized
mining activities, etc.) are required during
the construction period and license need
to be obtained to collect, transport, store,
recover, recycle or dispose waste or
establish any site or facility for the
disposal of any waste during the
construction and operation period.
CEA and Local Authority
Environmental Protection
License (EPL) from CEA/
Divisional Secretariat for
identifying waste dumping
sites /Local Authority/
Pradeshiya Sabha for
waste collection and to
issue machinery permits
2 Mines & Minerals Act No.
33 of 1992
The act regulates the process of approval
required for exploration, mining, trading
and transport of geological material
(sand, earth, gravel, metal etc.)
Geological Survey and
Mines Bureau
Industrial Mining License
(IML) from Geological
Survey and Mines Bureau
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6. CHAPTER 06 : MONITORING PLAN
6.1 Environmental Compliance and Monitoring
Environmental monitoring is required in order to make sure that the anticipated adverse
impacts are kept minimal with the implementation of mitigation measures as and when
required. The monitoring objectives are therefore focused on the mitigation of likely impacts.
In addition, compliance with the existing regulations and legislation is also guaranteed.
Table Error! Reference source not found. enumerates the summary of monitoring plan
(EMoP) required for the entire project.
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78
Table 6.1: Summary of Monitoring Requirement
Specific
Intervention
Monitoring
Parameters
Monitoring
Frequency
Total Time
Period
Months
Responsible
Institution/
Person for
Implementation
Responsible
Key Persons
for Supervision
Framework of the
Institutional Arrangement to
Incorporate the Findings of
MP to Project
Implementation
Improvement
s to tank
bund U/S
slope and
bund crest
(0+000 m to
1+775 m)
Slope
stabilization
and seepage
control
Construction
of access
road from
0+000 m to
1+775 m
Construction
of a vehicle
turning point
at the end of
bund road
Method and
procedure of
stockpiling of
material
At the
beginning of
the
intervention
During the
whole
intervention
Contractor
Project
Manager or his
nominee
PM to inform the contractor
of the monitoring and the
contractor to submit the
reports as agreed; Reports to
be submitted to the Project
Office (PO) and then the
reports be evaluated by
World Bank (WB) and PO for
approval.
Number of
complaints
received on the
inconveniences
caused in the
neighborhood
As and when
received
During the
whole
intervention
Contractor
Project
Manager or his
nominee
Turbidity in the
working section of
the tank
When such
incidents
are found
During the
whole activity
Contractor
Project
Manager or his
nominee
As mentioned above The extent to
which the turbidity
plumes due to
erosion in the
downstream water
courses run
When such
calamities
occur
During the
stock piling
period
Contractor
Project
Manager or his
nominee
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79
Specific
Intervention
Monitoring
Parameters
Monitoring
Frequency
Total Time
Period
Months
Responsible
Institution/
Person for
Implementation
Responsible
Key Persons
for Supervision
Framework of the
Institutional Arrangement to
Incorporate the Findings of
MP to Project
Implementation
Removal of
cleared
vegetation and
branches
When this
activity
takes place
When this
activity takes
place
Contractor
Project
Manager or his
nominee
As mentioned above
Stocks of stumps
removed
When this
activity
takes place
When this
activity takes
place
Contractor
Project
Manager or his
nominee
As mentioned above
Construction
of curtain
wall at U/S of
spill
Repairs in
D/S of sluice
Construction
of Gabion
wall for slope
protection
Providing
emergency
gates
The extent to
which the
turbidity plumes
due to erosion in
the downstream
water courses
When
turbidity
plumes are
found
During the
whole
intervention
Contractor
Project
Manager or his
nominee
As mentioned above
Timber logs
removed
When this
activity
takes place
When this
activity takes
place
Contractor
Project
Manager or his
nominee
As mentioned above
Removal of
cleared
vegetation and
When this
activity
takes place
When this
activity takes
place
Contractor
Project
Manager or his
nominee
As mentioned above
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
80
Specific
Intervention
Monitoring
Parameters
Monitoring
Frequency
Total Time
Period
Months
Responsible
Institution/
Person for
Implementation
Responsible
Key Persons
for Supervision
Framework of the
Institutional Arrangement to
Incorporate the Findings of
MP to Project
Implementation
branches
Construction
of boat yard
in
Angamuwa
tank at
1+500 m of
tank bund
Noise levels
When the
drilling is
done
During the
doweling
operations
Contractor
Project
Manager or his
nominee
As mentioned above
Vibration levels
When the
drilling is
done
When the
drilling is
done
Contractor
Project
Manager or his
nominee
Airborne dust
levels
When a
complaint is
received
During the
activity Contractor
Project
Manager or his
nominee
Cracks that
would appear in
other connected
structures
During the
activity
During the
activity
Contractor
Project
Manager or his
nominee
As mentioned above
Material
haulage from
borrow areas
Noise levels
When a
complaint is
received
During the
material
transport
Contractor
Project
Manager or his
nominee
As mentioned above
Environmental Assessment for Rehabilitation of Angamuwa Tank Draft Final Report
81
Specific
Intervention
Monitoring
Parameters
Monitoring
Frequency
Total Time
Period
Months
Responsible
Institution/
Person for
Implementation
Responsible
Key Persons
for Supervision
Framework of the
Institutional Arrangement to
Incorporate the Findings of
MP to Project
Implementation
Vibration levels
When a
complaint is
received
When a
complaint is
received
During the
material
transport
During the
material
transport
Contractor
Project
Manager or his
nominee
As mentioned above
Airborne dust
levels One in 10
vehicles of
borrow
martials
brought in to
the site
During the
material
transport
Contractor
Project
Manager or his
nominee
As mentioned above
Presence of
invasive species
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
82
7. CHAPTER 07 : COST ESTIMATE OF ENVIRONMENTAL MANAGEMENT PLAN
Table 7.1: Cost Estimate of EMP
Issue Mitigation Details of Costing Itemized Cost
Activities such as
material
transport, soil
stockpiling, etc.
may result in air
pollution through
airborne dust. If
there are dwelling
units along
haulage routes
there may be a
minor temporary
adverse impact
during this period.
Dust emission due to
transport operations should
be controlled by wet
spraying and tarpaulin
covering in mandatory on
trucks/lorries which are used
for transporting materials
particularly in built up areas.
Sprinkling of water
has to be carried out
using bowsers, or
tractors where there
are dwelling unit only
when necessary.
Lorries and truck
should be covered
(with tarpaulin sheets)
when transporting
earth and gravel.
Sprinkling of water:
Bowser: Rs. 5,000 -
6,000 per bowser
Tractor: Rs. 2,500
per tractor
Covering with
tarpaulin sheets:
Rs. 200/m2
Health and
sanitation of
worker’s camps
and that of
residents in the
adjoining areas:
The temporary
camps if not
managed
properly may
create an
unhealthy
environment
causing health
hazards to both
workers and
nearby residents.
Proper sanitation facilities
should be provided on-site
for the workforce. Ideally,
this can be a pit latrine in
which the pit is located
above the ground water
table. Covering the deposit
(with earth or sawdust) is
necessary to prevent smells
and to discourage flies.
Costs involved in
providing pit latrines Rs. 10,000 – 15,000
Operation of
borrow pits
Erosion and
slides in borrow
areas occurring in
hillocks would
lead to loss of
Closure of borrow pits
properly
After borrowing the
slope/gradient of the area
should be graded to match
or blend with the existing
terrain.
The costs that may
incur involve grading
of borrow pit edges
Cost of construction
depends on the
scale of the borrow
pit. The typical cost
of rehabilitation
would be Rs.
500.00 / m2.
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
83
Issue Mitigation Details of Costing Itemized Cost
topsoil and
vegetation loss,
hence habitat
loss.
Re-establishment
of vegetation
would be
hindered due to
loss of fertile soil
Any borrow pits
on the tank bed
also should be
graded properly.
Plant the area with native
trees and water regularly
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
84
8. CHAPTER 08 : CONCLUSIONS AND RECOMMENDATIONS
8.1 Conclusions
The following conclusions could be deduced for the entire environmental assessment.
The project area does not have any environmentally sensitive features, endemic or
threatened flora and fauna specific to the neighborhood. No archaeological sites, cultural or
religious sites are found in the project area.
All the interventions are accepted without any specific environmental mitigation measures.
Nevertheless, best practices listed on the EMP should be practiced as practical as possible.
ICTAD specifications on civil engineering practices must be followed as and when
applicable.
Alternative route must be identified for the commuters on the bund when the bund
construction is in the progress. However, construction work should be complete as early as
possible so as to minimize the inconvenience caused in the neighborhood.
All the borrow sites need better managements in order to avoid or minimize pollution
potential and best practices for managing sites should be adopted.
The proposed project will therefore be carried out together with the implementation of
mitigation measures stated in this report.
8.2 Recommendations
The following recommendations are imperative to be adhered to for the management of the
environment during the project realization period.
Borrow site in the tank bed must be utilized with a proper rehabilitation and safety plan for
the protection of fauna inhabiting the area. All the other borrow areas should be accepted for
material exploitation only if proper approvals from the relevant authorities are obtained.
Engineering best practices must be recommended to be adopted by the contractor for the
sound engineering work.
When complaints are received from the neighborhood on the environmental issues,
immediate attention and solutions to such issues are recommended.
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
II
Annex 1: Details of the Farming Community
Farmers who were interviewed individually
Serial
No Name Position Address TP No
1 D. M. K. H.
Dissanayake P.M. I M D Rajanganaya 0716317003
2 S. Thilina Development
Officer I M D Rajanganaya 0716423330
3 N Anuruddika Development
Officer I M D Rajanganaya 0712389129
4 N Saratha
Gaminie President
Pradesiya Saba,
Rajanganaya 0725458466
5 P Nihal
Wanniarachchie President Rajanganaya 0715153538
6 S Chaminda
Kumara Secretary
Fisheries Committee,
Angamuwa 0725152413
7 H M K Nimal
Jayatissa President
Track 6, Farmers
Association, 501,
Angamuwa
0726152034
8 K P Dhanaratna Secretary
Track 7, Jaya Sri, Farmers
Association, 700,
Angamuwa
9 W M Nimal
Samaraweera President
Kethsiri Farmers
Association, Track 9,
Gemunupura, Rajanganaya
10 Y G Gunaratna Farmer Track 8, Angamuwa,
Rajanganaya
11 W Seelawathie Farmer Track 8¸ Angamuwa,
Rajanganaya
12 A W Abeysinghe Farmer Track 8, Angamuwa,
Rajanganaya
13 U Nandawathie Farmer Track 8, Angamuwa,
Rajanganaya
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
III
14 W G Piyadasa Farmer Track 8, Angamuwa,
Rajanganaya
15 N Upali
Ranaweera President
Track 8, Angamuwa,
Rajanganaya
16 G G Anura Farmer Track 8, Angamuwa,
Rajanganaya
17 J Gunatilake Farmer Track 6, Angamuwa,
Rajanganaya
18 M Premawathie Farmer Track 6, Angamuwa,
Rajanganaya
19 J M Nandawathie Farmer Track 6, Angamuwa,
Rajanganaya
20 S. P. Sam Farmer Track 6, Angamuwa,
Rajanganaya
21 W Upali Farmer Track 6, Angamuwa,
Rajanganaya
22 D M Ariyaratna Farmer Track 6, Angamuwa,
Rajanganaya
Details of the group discussions that were held during the study
FGD Participants Total Venue
Female Male -
1 2 5 7
Kethsiri Farmers
Association,
Track 9,
Gemunupura,
Rajanganaya
2 2 4 6
7, Ela,
Angamuwa,
Track 7
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
IV
Annex 2: Details of the encroached farmer families
Name Employment Family size
G.H.Gamini Ornamenctal flcower
growing 5
M.Sunil Labor 3
H.A. Kularathna Farming 4
K.A. Jayathilaka Farming 4
M.R.Tennakoon Self employment 2
W.A.Irangani Farming 3
W.M. Karunadasa Private sector 4
S.Padmasiri Self employment ( Poultry
Farm) 4
A.G. Albert Framing 4
Total 9 35
S
Numbe
r
Name
Extent Property Impacted Details
Leng
th-m
Wid
th-m
Exte
nt-
m
Coconut-
No
Ban
ana b
ush
es-
No
Sha
llow
wells
Toile
ts
Pou
ltry
farm
1 G. H
Gamini 200 5 1000 15 0 0 0 0
Residential
land but no
impact on
the house
coconut
trees are
about 5m
away from
the bank
2 M.Sunil 150 5 750 0 15 0 0 0
No house
available.
Banana
bushes are
6m from
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
V
the bank
3 H.A
Kularathna 100 5 500 8 0 0 0 0
No house
available.
Coconut
trees are
5m from
the bank
4 K.A
Jayathilaka 150 5 750 5 20 0 0 0
Residential
land.
House is
far from
the bank.
Coconut
and
banana
are 6m
from the
bank
5 M.R
Tennakoon 75 5 375 2 0 0 0 0
Residential
land.
House is
far from
the bank.
Coconut
are 5m
from the
bank
6 W. Irangani 50 5 250 0 0 0 0 0
Bare land
but a
house is
being
constructe
d in a
place far
from the
bank
7
W.M
Karunadas
a
100 5 500 0 0 0 0 0 Bare land
8 S.Padmasir
i 150 5 750 4 0 1 1
1
(10x20
feet)
Residential
land.
House is
far from
the bank
but toilet,
well and
part of
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
VI
poultry
farm may
get
affected
these are
located
from 6m
from the
bank
9 A.G Albert 150 5 750 5 10 1 0 0
Residential
land,
house is
far from
the bank,
the trees
and the
well are
located
about 5m
from the
bank
total 975 5625 39 45 2 1 1
VI
Annex 3: Land area in Gravity and Lift irrigation systems in Angamuwa tank
FO Command area-Acers
Gravity irrigation system
Arunnalu – Track 6 252
Jayasri – Track 7 182
Mahasen – Track 8 298
Nethsiri – Track 9 232
Ruhunu – Track 10 246
Ranketha – Track 11 402
Predeepaloka – Track 12 358
Ekamuthu – Track 13 480
Pregathi – Track 13 144
Vijaya – Track 14 390
Jayamaha – Track 15 434
Youth FO – Track 16 530
Saraketha- Track 17 640
Sri Vijaya –track 18 227
Total 5194
Lift irrigation system
Track 6- BOP 397 Dimuthu 81
Track 6 BOP 716 Purasanda 284
Track 7 BOP 717/1 Suhada 59
Track 7 BOP 560/A Nava Jaya 111
Track 8 BOP 561 Pubudu 41
Track 9 BOP 560 Udara 220
Track 15 BOP 607 Track 11, 15 210
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
VII
Track 15 BOP 717/2-Ekamuthu 360
Total 987
Annex 4: Details of the cost benefit of an acre of paddy land in Angamuwa tank
Gross income Rs. Expenditure item Rs.
2,442 kg (110
bushel * 22kg) 85470/- (2,442*35) Ploughing (tractor) 8,500
Preparation of field
bank (activity 1) 3,600
Preparation of field
bank (activity 2) 4,800
Seed paddy 3,400
Basel fertilizer 600
sowing 4,800
Agrochemical 1 3,500
Agrochemical 2 1,200
Second application
of fertilizer 600
Agrochemical 3 750
Agrochemical 4 1,200
Third application of
fertilizer 600
Harvesting 7,500
Transport of paddy 2000
Drying of paddy 3,600
TOTAL 46,650
Note: Gross income Rs. 85470/-, total expenditure Rs. 46650/- therefore net income Rs
38,820 /=
Environmental Assessment for Rehabilitation of AngamuwaTank Draft Final Report
VIII
Annex 5: Map showing the vicinity of Angamuwa tank