DEMOCRATIC SOCIALIST REPUBLIC OF SRI LANKA ... ... using a trailing suction hopper dredger. The area...

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Transcript of DEMOCRATIC SOCIALIST REPUBLIC OF SRI LANKA ... ... using a trailing suction hopper dredger. The area...

  • DEMOCRATIC SOCIALIST REPUBLIC OF SRI LANKA

    MINISTRY OF TRANSPORT AND HIGHWAYS

    OFFSHORE SAND MINING FOR THE

    COLOMBO 7

  • OFFSHORE SAND MINING FOR THE

    COLOMBO KAiUNAYAKE EXPRESSWAY PROJECT

    m^^^ IKONi iftiTjaii /j»ö.miöaßi?Fr-miMß»

    ROAD DEVELOPIVIENT AUTHORITY

    "Sethsiripaya", Battaramulla

    SRI LANKA

    DECEMBER 2000

  • OFTMIOHE I)U[JX;IN(; RIR C()U)MR() KATUNAVAKE EXPRESSWAY PROJECT

    Eiiviromiiciilal lnip;)Ct Asscssiiicnl Ucpoil

    TABLE OF CONTENTS

    1.0 Introduction 1

    1.1 Background 1

    1.2 Extent and Scope of the Study 2

    1.3 Brief Outline of the Conlentsand Methods Used 2

    2.0 Description of the Project 4

    2.1 Nature, Aims and Scope of the Project 4

    2.2 Justification of the Project 4

    2.3 Methodology of Operation 5

    2.4 Evakialion of Alternatives 7

    2.5 Workforce 10

    2.6 Programme 10

    3.0 Borrow Area and Dredging 11

    3.1 Location and Size of Proposed Borrow Area 11

    3.2 Volume and Type of Material 11

    3.3 Method of Dredging 11

    3.4 Timing, Rate and Zoning of Production 12

    3.5 Vessel Numbers and Movements 12

    3.6 Control of Dredging 12

    3.7 Notification and Liaison 12

    3.8 Onshore Destination 12

    3.9 Alternative Sources of Material 12

    4.0 Borrow Area and its Environment 13

    4.1 Physical Environment 13

    4.2 Biological Environment 13

    4.3 Human Environment 15

    4.3.1 Fishing Activities 15

    4.3.2 Other Activities 17

    5.0 Sand Storage Sites and Their Environment 18

    6.0 Anticipated Environmental Impacts 19

  • Ün>iHORKDRi:D(;iN(; R)RCnU>MH() ICVTIINAVAKE EXPRIiSSWAY I * R 0 J E C T

    Eiivironmciilal Impacl Assessment Rcjwrt

    6.1 Physical Effects 19

    6.2 Biological Effects : 20

    6 3 Effects on the Human Environment 21

    7.0 Proposed Mitigatory Measures 22

    7.1 Royulaiiüii/'Müiiitoiiny ufDicdging Activity 22

    7.2 Protection of Borrow Areas 22

    7.3 Coastal Stability 22

    7.4 Navigational Hazards and Interference with Fishing Activities 22

    7. 5 Pipeline on Land and Crossing Hamilton Canal 23

    7.6 Sea Water Impacts on Surface Water and Groundwater 23

    8.0 Monitoring Programme 24

    8.1 Dredging Activities 24

    8.2 Pumping/Drainage Activities 24

    8.3 Long Term Monitoring of Dredge Site 24

    9.0 Conclusions and Recommendations 25

    ANNEXES ANNEX 1

    ANNEX 2

    ANNEX 3

    ANNEX 4

    ANNEX 5

    ANNEX 6

    ANNEX 7

    ANNEX 8

    Terms of Kcfcrciice

    Bathyntctric Survey Plan

    Construction Programme

    Mincralogical Analysis

    Seismic SuiTcy Report

    NARA Report on Fisheries and Marine Habitat

    Boreholes Investigation Report

    Section 5,4.1.1 Dredging and Transport of Sand to

    Stockpiling Area (ElA Report of Colombo-Katunayake

    Expressway RDA 1997)

  • IÄFSIIOREDREDGINC FOR COLOMBO KATUNAYAKE EXPRESSWAY PRO.TECT ^T

    Fnviroiimciilal Impact Assessment Report

    LIST OF HGURES

    Figure 1 - Location Map fui Dreilging

    Figure 2 - Location of Stockpiling Areas

    Figure 3 - Proposed Trace of tlie Express Highway

    Figure 4 - Typical Cross Section of the proposed Highway

    Figure 5 - layout of the Submerged Pipeline

    Figure 6 - Layout of Boreholes

    Figure 7 - Resource Map (Isopatch Chart)

  • OFFSHORE DRF.IK;IN

  • OFFSHORE DREDGING FOR COLOMBO KATUNAYAKE EXPRESSWAY rROjECr Environmental Impact Assessment Report

    1.2 Extent and Scope of the Study

    Tlie EIA is to evaluate the impacts of removing a volume of approximately five million cubic

    metres of well graded medium to coarse sea sand from the grid units designated 093203,

    093204, 094203, 094204, 095203 and 095204 (see Figure No. 1). The area is located

    approximately 3 km offshore of Kerawalapitiya. just north of Colombo. The average sea

    depth at the location is 16m below LWOST. The area of dredging is 6 sq. km. and the

    average depth of excavation will be approximately 1 .Om.

    The scope of the study is to evaluate the aviulability of the required material and the effect of

    removal on the wave climate, ajid Impacts on fisheries, shoreline stability and natural resources

    of the area.

    The methodology for pumping sand to a stockpiling area (also shown in Figure No. 2) and the

    arrangements made for the return of saline water to the sea was to follow the practices adopted

    for the Kerawalapitiya sand fill {see EIA Report, SLLRDC 1993). Originally the stockpile

    was to be made within the Kerawalapitiya sand fill (see EIA Report - RDA 1997, and Relevant

    Section in Annex 8). This methodology had already received clearance from the CEA.

    However, the an alternative site , adjacent to the Kerawalapitiya and fill has now been reserved

    for the stockpile. The methodology for sand fill and evacuation of drainage water remains

    / neariy the same. However, the impacts of filling this area and the return of saline water from

    this area have also to be included in the study.

    1.3 Brief Outline of (he Contents and Methods Used

    The EIA Is formatted to follow the Terms of Reference (TOR) provided by the CEA. It

    provides a description of the project, a site description and a description of the existing site

    environment, a description of the anticipated environmental impacts, proposed mitigatory

    measures and the monitoring programme to be followed.

    TTiere have been two dredging projects implemented in the area immediately adjacent to the

    site. These were for the purpose of obtaining approximately one million eubJc metres of sea

    sand for filling purposes for the JA YE Container Terminal Project In the Colombo Harbour,

    and for obtaining approximately 4.8 Million cubic metres of sea sand for the Kerawalapitiya

    Reclamation Project. The Queen Elizabeth Quay Expansion Project has recently received

    environmental clearance to obtain 1.69 million cubic metres of sea sand from an adjacent area.

    An EIA and an lEE (Initial Environmental Examination) were carried out respectively for the

  • On->"HORF. T)RFDf;iN(; FOR COLOMBO KATIINAYAKF, EXPRESSWAY PROJECT 3 Enviroimiciilal Impact Assessment Report

    the purpose of this EIA. The additional field investigations carried out for the present study are

    described later in this report. All available information on the fishery and the reefs in the area

    were studied.

    The results of these investigations, studies and assessments are presented in tliis EIA.

  • OiTsiiORE DREDGING FOR COLOMBO KATUNAYAKE EXPRESSWAY PROJECT 4 Environmental Impact Assessment Report

    2.0 DESCRIPTION OF TlIE PROJECT

    2.1 Nature, Aims and Scoi>e of tlie Project

    The need for a high speed link between Colombo and the International Airport and Export

    Processing Zone in Kalunayake has been recognised from the I980's. The consirnction of the

    Colombo-Kafunayake Hxpnsssway (CKE) along a final trace (see Figure No 3) was finally

    approved by the C^inet of Ministers on 26* June 1998, after a prolonged planning process

    which included extensive public consultations. The Environmental Impact Assessment Report

    on this project was approved by the Central Environmental Authority on 28 January 1998.

    The final design of the expressway (as shown in Figure No 3) has the following main

    jiaramelers:

    Lengtii (km)

    Width of reservation (m)

    Width of eadi carriageway (m)

    Number of Inter changes

    Southern Terminus

    Northern Terminus

    25.10

    30-100

    27.20 (Four Lanes)

    02 (Peliyagoda and Ja-Ela)

    New Keiani Bridge Intersection

    Airport Intersection

    Figure 4 shows the typical cross section of Ihe road.

    The CKE trace runs through significant extents of marshy land witli peaty under-layers. The

    proposed methodology for pre-loading and draining these layers has been considered in the

    previous EIA. The metliodology requires the use of 5 million cubic metres of sand obtained

    from offshore as fill material. The original CKE proposal was to mimic the procedure adopted

    for the Muthurajawcia sand fill and environmental clearance was therefore granted. The new

    proposals suggest the use of a storage area (see Figure No. 2) on the eastern side of the Dutch

    Canal (Old Negombo Canal). This proposal has thus been included in this present EIA,

    TTie originally proposed borrow areas are no longer available to this project. Thus it has been /

    necessary to explore tlic availability of sand in new, adjacent areas and carry out a full

    environmental impact asst̂ ssment of dredging and tmnsporting Ihe sand from these new areas

    and to satisfy the Geological Survey and Mines Bureau (GSMB) licensing procedure for

    exploration and mining.

    2.2 Justification of the Project

    The justification for the CKE Project has been deaJt with exhaustively in the main EIA Report

    (RDA, 1997). The need for the expressway has been established and the choice of a road link,

  • OFI^IIÜRE DREDGING POR COLOM