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8/10/2019 Manzanilla-Mayaro Road Repair Works
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Manzanilla-Mayaro Road
Repair Works
Water Management - Drainage Interventions
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ON THE GROUND(17THNOVEMBER 2014)
COASTAL CONDITION SURVEY
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Breach #1
High Beach Dune relative to
road level
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Breach #4
Overflow from wetland flowing
across and under the road.
Lack of interceptor drainage
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AERIAL SURVEY
COASTAL CONDITION SURVEY
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Overflow from wetland
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Breach
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BREACH LOCATIONS/OUTFALLS
COASTAL CONDITION SURVEY
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OUTFALL #1
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OUTFALL #6
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OUTFALL #12
Photo taken looking
towards shoreline
Photo taken lookingtowards the road
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OUTFALL #16
Major breach at the location of the damaged
house.
Sandbag being used by homeowner to protection
against ongoing erosion. Sandbag located on
northern side of breach (Outfall 16)
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OUTFALL #17
Major breach. At this location the entire road
cross section failed. No vehicular traffic beyond
this location
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PROPOSED DRAINAGE WORKS
MANZANILLA-MAYARO ROAD REPAIR WORKS
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Manzanilla-Mayaro Road Repair Works
Problems Opportunities
Solution
(Mimic the natural
drainage processes)
Failed sections of the roadway rendering the route
impassable
High topography of the beach dune
provides a natural defence against
coastal inundation or run-up by the
sea
Construction of interceptor drains (on
western side of the road) and
collector drains (on eastern side of the
road)
Paucity of drainage (natural and/or anthropogenic) Channels created during the flood
event can provide drainage from
inland runoff
Construction of culvert crossings to
channel flow from interceptor drains
(western side of the road) to collectordrains (eastern side of the road)
Relatively high topography of the beach dune in
comparison to the existing elevation of the Manzanilla-
Mayaro Road creating a natural impediment to drainage
Permanent establishment of 7 8
major breaches using green
technology (marine cells/marine
mattresses)
Ongoing coastal erosion threatening critical areas along the
Manzanilla-Mayaro Road, that is high water mark is less
than 15 meters from the existing roadway
Installation of inline check valves or
tideflex values to prohibit the
intrusion of saltwater into the wetland
Intense rainfall over a relatively short period (e.g. 371mm
over 9 days). It is noted that the long term (30-year) rainfall
depth for the month of November is 227.8mm
Residential and resort properties have been constructed
between the Manzanilla-Mayaro Road and the shoreline.
In many cases the structures are close to the roadway. This
provides a challenge for widening and elevating the road
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In line check valve or tideflex valve. Allowing only
one direction of flow at this point along the culvert.
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Breach #1
Breach #4
Breach #8
Breach #10
Breach #12
Breach #16
Breach #17
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COASTAL INTERVENTION
MANZANILLA-MAYARO ROAD REPAIR WORKS
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Proposed Coastal Intervention South Cocos
Proposed protection measures for the four shoreline sections
Sect.Road to be
protected against Proposed protection measure
Flooding Erosion
1 Yes Yes
Reinforcement of existing concrete seawall and
a new rubble mound seawall
2 Yes Yes Seawall type structure landwards of the
coastline3 Yes Yes
4 Yes No
Dyke located relatively close to the road to
allow natural coastal processes to take place
but preventing flooding of the road. This
involves gradual sacrificing of the coconut
plantation
Risk classification for coastal flooding and for coastal erosion
for the 1200 m long project stretch
Section Distance to
road [m]
Risk for
flooding
Risk for erosion
of road of road
1 0 Critical Critical
2 0 to 35 Critical Critical
3
25
Critical
Critical
4 50 to 60 Critical Not critical