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St Vincent and the Grenadines
Central Water and Sewerage Authority
Report on damages to the Jennings and
Perseverance Treatment and Supply Systems
and Restoration works April !""
Prepared #y$ %ngineering &epartment
&ate$ "'th(ay !""
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Table of Contents
Introduction
Outline of the Damage sustained to CWSA systems and Installations
Restoration and Repair works
ist of !ipes and "itting used during disaster relief
ist of construction materials used during disaster relief
ist of #$uipment and %achinery used during disaster relief
abour force used during disaster relief
Introduction
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)n the ""tho* April !"" heavy rain*all in the Perseverance and Jennings
valley+ "", and "!, respectively+ resulted in swollen rivers and severe
-ooding that in turn caused signi.cant damage to two o* our ma/or systems
on the windward side o* the island0 The a1ected systems were Jennings
Treatment and Supply system also known as the Windward Supply Pro/ect
and the Perseverance Treatment and Supply system that *eeds Georgetown
and surrounding areas0 The o#/ective o* this report is to document the post
disaster e1orts o* the Central Water and Sewerage Authority as it relates to
the reha#ilitation works done on our systems and its inter*ace with the
community in #oosting its resilience to cope with intermittent water
shortages0 An added e2pectation is that this report will assist in
supplementing a *avoura#le institutional *ramework to strengthen even
*urther our disaster management plan0
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Outline of the Damage sustained to CWSA systems and
Installations
On the !erse&erance system the ma'or damages were sustained in
the following areas(
(assive agglomeration o* #oulders+ logs and sediments at the intake
dam as well as a #uild up o* sediments in the grit cham#er rending
#oth una#le to *unction0
#reakages on the 3, ductile 4ron pipeline *rom the intake to the
Treatment plant0
At the 5!+!!! gallon storage tank over-ow the pipes were swept
away and outlet valves were shi*ted as well as an accumulation o*
sediments within the tanks cham#ers0
6evel sensors and 7low meters *rom the water resources pro/ect were
swept away #y the swollen river0
There was also scouring at the #ase o* the storage tank that may
threaten the structural integrity o* its *oundation and degradation o*
the slopes #etween the road and the tank that will re8uire retaining
structures to sta#ili9e same0
A '5!: section o* *ence closest to the river was swept away0
' ;reakages on the 3, ductile 4ron transmission main *rom the
treatment plant at the 'rd+ )ne at its river
crossing in Spring+ Georgetown and the other at the river crossing at
(ount ?oung where it supplied water to Chester Cottage0
" ;reakage on the
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There was also the *ailure o* a retaining wall that supported a portion
o* road a#ove the river #etween the .rst and second river crossing0
The #ridges were signi.cantly damaged as they were clogged in most
instances and the water eroded the weaker portions #e*ore and a*ter
completely destroying the roads and in some cases scouring their
*oundation and a#utment walls0
On the )ennings System the ma'or damages were obser&ed in the
following areas(
;reakage on a section o* the =, pipeline *rom the intake to the
treatment plant as a result o* a mass movement o* a signi.cant portion
o* the land0
The gate and '
one at the stream in *ront o* nights property+ two in the pro2imity o*
the hill a#ove knights #ridge+ one close to knights #ridge+ one en route
#etween ;yrea and Jennings at the .rst wash out and two suspended
river crossings at ;yrea proper0
The roads sustained similar damages to those in the perseverance
valley> high volumes o* sediments and huge logs rendered them
impassa#le0 4n some sections where the road runs parallel to the river
there was mass erosion o* the river #anks that signi.cantly reduced
the width o* the carriageway as well as landslides that causes road
#locked0
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The #ridges and river crossings were not as #adly a1ected and were
mainly #locked hence a1ecting their *unctionality and not their
structural integrity0
There was also damage done to the
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Cleaning o* the intake also #egun on that day as well as shuttling o* Pipes *rom
;elair Comple2 to ;yrea as the ;ridge at (t0 ?oung and conse8uently the #ridge at
;yrea were impassa#le0 )ur assessments continued until Thursday the "
T& B and G
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changes its course0 There are also plans in place to cover the pipeline
with mould or sand *rom the river #ed to act as a cushion and reduce
the vulnera#ility o* the pipes with respect to the ad/oining slope0
The .tting at the Storage tank over-ow were replaced on the B thand
3tho* April while the removal o* de#ris and -ushing o* the tanks weredone on those days #y la#ourers0
The #reakages on the 3, lines were repaired strategically *rom the 'rd
crossing upwards towards the treatment plant0 )n "= th o* April
lengths o* 3, -anged ductile iron pipes were .tted along the third river
crossing+ concrete works are yet to #e carried out at this point0 )n the
"Btho* April lengths o* 3, #ell H Plain and lengths o* 3, 7langed
pipes were used to restore the
thick layer o* concrete around '!: o* the pipe surround where the river
is e2pected to -ow0 (i2ing o* concrete was done #y mi2er with a mi2
ratio o* "$$< and the mi2 was transported #y ;uggy+ this was done
#etween the "3thand the "tho* April0
4n the second phase the 3,pipeline that was previously laid was
#ack.lled using sand that was transported *rom &ickson+ Georgetown
#y ;uggy and with the compliments o* (r Selwyn &a#reo0 The rivercourse was then diverted over to the concrete protected section o* the
pipeline again #y (r Austin ;ullock who also did the trenching *or the
second phase0 We then proceeded to /oin the pipes to the e2isting
pipeline at the other e2treme o* the river #y installing a *urther 5 I
lengths o* 3, &040 pipes0 )nce this was completed we then placed
concrete protection over a *urther !: o* pipeline as the natural course
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o* the river in that areas is #oth unpredicta#le and is also lia#le to
change when the #ridge is reconstructed hence a very conservative
approach on our part0 The concrete works were 8uite challenging as
the tires o* our #uggy were punctured on various occasion and we had
to resort to the use o* the ;ackhoe G
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&040 *rom the treatment plant+ concrete works were then carried out at
a later date0
The Chlorination *acility has since #een cleaned #y la#ourers+ the
#reakages on the ", chlorine line and the chlorine sample point stand
pipe has also #een repaired0
Repair works on the ", transmission mains are as *ollows$
At the two suspended river crossings at ;yrea one length o* ", &040
-anged pipes was used in #oth instances as well as a -anged adaptor0
At the .rst washout *rom Jennings in the direction o* ;yrea I lengths
o* ", &040 -anged were used to repair that section0
Close to knights ;ridge where originally there was ;ell and Plain Pipes
that were washed away+ ' lengths o* 7langed pipes were used as well
as welding to e1ect the anchors0
4n the pro2imity o* the hill a#ove knights the two #reakages re8uired =
I lengths o* ;ell and Plain pipes to reinstate that segment+ and < I
lengths respectively0
The stream in *ront o* knights ;uilding ' I lengths o* " &040 -anged
pipes were used to replace the ;ell and plain pipes o* the same
diameter that e2isted there0 Concrete works were also done throughout
at all o* these locations to secure the pipelines #y providing thrust
#locks+ anchors and Supports0
The damaged
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