LA cJ:)l i
'R E P. R T
GOVERNMENT OF .ATRINIDAD AND TOBAGO
SETERAGE FACILITIES for SOUTH WEST
REGION. I, TOBAGO.
-GOVEIISENT OF TRINIDAD AND TOBAGO,
(Ministry of Planning & Development).
SOUTH WEST REGION I
ATTAS & DE FOUR,
19, Szanmore Avenue,
Port of Spain.
UNIVERSITY OF FLORIDA
3 1262 07275 177 8
TABLE OF CONTENTS
Summary of Conclusions and Recommendations
Scope of Work
Metcalf & Eddy Proposals .
Possible locations of Outfalls
Construction Costs i
Appendicies A-' Report by C.A.W. Deane
'3B Plans of Alternatives
SUMMARY OF COACLUSICS AND RCOVAMENDATIONS.
We submit the following Summary of conclusions and
(1) The present rate of development in South Western Tobago
and the planned growth of tourism amply justify the need for
sewerage facilities in the area.
(2) No sewage effluent should be discharged on the North
Western coast of the island because of-possible adverse effects
to the ecology of Buccoo Reef.
(3) All areas in the Western tip of the island should
havel:ne sewerage'system with single treatment plant at Crown
Point and interconnecting trunk lines between Buccoo and
Canaan. The final effluent should discharge Southwards at Crown
(4) Trunk lines should be sized to cater for the future
population between Buccoo and Canaan.
(5) Design Criteria should be as recommended in the Metcalf
& Eddy Report.
(6) The construction of the system'should be phased into
three (3) separate contracts in order of priority as follows:
(a) Treatment Plant;
(b) Trunk line, pumping station and force mains;
SUV.IARY OF CONCLUSIONS Cont'd.
(7) Temnporary facilities in vhe form of package type
treatment plants should be provided for new Hotels that will be
ready before the main sewerage facilities are commissioned.
SCOPE OF WORK:
(1) Review of Metcalf & Eddy's Feasibility Report dated 23rd
September, 19i8 -
(2) Initiating and obtaining results of specialized surveys
(3) Investigation of current and tidal conditions in order
to determine the possible effects of sewage effluent on
beach and hotel development as well as the ecology of
the Buccoo Reef.
(k) Field reconnaissance to determine the extent of the area
to be served and the general pattern of the collection
(5) Examination of available maps and pertinent engineering
(6) Examination and evaluation of basic design criteria
as set out by existing feasibility report.
(7) Preparation of general layouts and drawings of possible
('8) Preparation of cost estimates and final recommendations
as to the most practical and economical layout.
MRCJCA U & 'S^Y 'S ?r'aOP3.ALs:
he South Western part of the Island of Tobago was divided
in'o two regions. Tne reZion to whicl this project applies is the
South West Region I and includes Buccoo, Crown Point, Canaan, Bon
Accord and surrounding areas (Ref. M&E Pages 41 & 42).
For sewerage purposes the region was grouped into three
sewerage zones as follows:-
(1) Crown Point Store Bay ilford'Bay;
(2) Canaan Bon Accord;
(3) .Buccoo Mount Irvine.
The Report made recor,,endations for a common system for zones, (1)
and (2) and another system for Zone (3).
The Treatment Plant for Zones (1) and (2) located in the
Western tip of the Island at the West end of the existing airport with
the effluent discharging into Milford Bay.
The Tre.atment Plant for Zone (3) was to have been located
in the vicinity of the mouth of the Courland River, with outfall to
Little Courland Bay. The report suggested that extensive studies be
performed over an extended period for reassurance that their effluent
will not change the ecology of the Buccoo Reef.
The basic design criteria for sewers, treatment plant
and pumping station as outlined in the Metcalf & Eddy Report are
in all respects quite adequate and will be used with minor
modifications as local conditions dictate. Items such as pipe
materials, equipment manufacture, standby requirements, etc.,
will be selected after consultation with the Water and Sewerage
~OSS.;~L3Z c;.J T C~ C;.iZ;r'L,..,
It is felt that the discharge of waste effluent that will nor-
mally be high in nutrients may have detrimental effects oi the: ecology
of the Buccoo 2eef.
A report was requested of Mr. C.A.W. Deane, Consultant on
Beaches, UWI, St. Augustine on the possible effects of effluent on the
flora and fauna of the reef and the prevailing currents and tidal patterns
along the coast, of the Island. Mr.Deane's Report is attached as
This study indicated a high probability of ecological changes
around Buccoo Reef, Buccoo Bay and Little Courland Bay and recommends
that no sewer outfalls be located in the Little Courland Bay. It also
pointed out that the entire South West coast between Lowlands Point
and Crown Point is suitable for sewer outfalls.
The two most suitable points of discharge being South of
the Crown Point Airport and the South-Western extremity of Petit Trou.
Because of the lack of information on the ecology of the
Buccoo Reef very extensive studies are required before a safe decision
can be made as to the effect of discharging sewage effluent in close
proximity to this reef. We therefore recommend that the Buccoo Treatment
Plant suggested in the Yetcalf & Eddy Report be not constructed in the
In the light of the present rate of Hotel Development in
this region it is not advisable, at this stage, to postpone commence-
ment of detailed desigs until the results of any studies are forth-
coming, simply to justify the locating of a Treatment Plant in the
Buccoo Area. We think that the Reef is too valuable to the Tourist:
Industry Development in this Island tA risk the possibility of
adverse ecological changes. We therefore recommend that the waste
from the Buccoo Area be pumped to combine with that from the Canaan-
Bon Accord system. This proposal involves the addition of approxi-
mately a mile and a half of 30" trunk line, a quarter mile of 18"
force main and a pumping station. Although this system will entail
additional expenditure,this trunk line will serve in the future all
areas between Buccoo-Mount Irvine and Canaan, which includes Golden
Grove. and-Mount Pleasant. These areas were not considered by the
Cost comparison of the various alternatives will be made
in another section of this Report, but it will be shown that the
additional cost of the combination of the two systems to avoid dis-
charging effluent into the Little Courland.Bay will be economically
We concur with the Metcalf & Eddy's recommendation of
oxidation pond type of Treatment Plant because of its high degree
of treatment, particularly in the tropics its ease of maintenance
and operation and low initial construction cost.
Three (3) sys te. were considered for the sewering of
the South West Rcion I. Each system involved a combination of the
waste from the three (3) Zones referred to in this Report and one
common sewage Treatment Plant.
The three (3) alternatives are shown in Appendix 'B'.
All three (3) Schemes are similar in one respect, that is, the
sewering of the Buccoo-Mount Irvine Zone and the trunk line link
to the Canaan one.
The basic differences between the alternatives are -
(1) Tho location of the Treatment Plant;
(2) The direction of flow in and location of mains;
(3) The sizes of the Pumping Stations.
The ultimate design population of. all systems will be
The system can generally be described as follows:-
This system will consist of a total of 57,360 feet of
lateral sewer, 29,960 feet of trunk sewer, four (4) Pumping Stations
and 10,880 feet of force main. Two (2) Pumping Stations in the
Buccoo area were originally suggested in the Metcalf & Eddy Report.:
The Orange Grove Pump station is a new proposal now necessary
because of the combination of the system. The Milford Main Road
Pumping Station will be bigger than originally suggested. A system
of laterals, is shown, construction of which should be phased in
accordance with the development of the areas concerned.
The Treatment 'Plant would be located on the coast
North West of the existing airport and would be of the oxidation
pond type as originally recommended.
The effluent would be discharged South at Crown
This system consists of a toTal of 57,360 feet of
lateral sewer, 26,040 feet of trunk sewer, five (5) Pumping Stations
and a total of 11,700 feet of force main. The location of the
Treatment Plant is the Kilgwin Swamp and the outfall just West of
Canoe Bay. Current studies indicate that this outfall may be
detrimental to beach development in the La Guira Area. The dis-
advantage of this system is the fact that sewage from all areas
West of the Treatment Plant flows against the general grade of
the land, thus necessitating an additional Pumping Station and
deep cuts. The Buccoo system will combine in the same manner
as in Alternative I.
This system involves the same payout as Alternative II
except that the Treatr.ent Plant is located in the Lowlands Area
and makes use of the best location for safely discharging effluent,
but involves additional trunk sewer. The system consists of a
total of 57,360 feet of lateral sewer, 37440 feet of trunk sewer,
five (5) Pumping Stations and 11,700 feet of force mains. Again
this system involves deep cuts and an additional Pumping Station
because the general flow direction is adverse to grade of the
Although Alt..rnaiv III makes use of one of the best
plant sites in terms of outfall conditions and availability of land
with low land use capabilities., it .d Alternative II are more
costly than Alternative I in terms o~ initial capital cost. From
the points of view of ease of construction and functioning Alternative I
is the most practical and economical system. We therefore recommend
that Alternative be accepted.
CCx S ?'rUCT"'Ip COSTS.
The fo1lowinr is s bresakown aC construction cost-of the
three (3) Alternatives as well as the Metcalf & Eddy proposal updated
to current costs:-. :...
Alter- T/.Plt .'uTr un. Lateral Force Pumping
natives & 0/fl_ Sewer Sewer Y Main Station TOTAL
I 2,308, 000 1,977,300 1,690,000 200,000 540,0boo 6,715,3.c
II 2,308,000 1718,640 1,690,000 451,000 .594,000 6,761,640
III 2,308,000 1,718,640 1,690,000 693,000. 600,000 7,009,640
.& E. 2,035,656 1,632,802 1,562,688 203,521 150,822 5,585,486
yotal Cs _______s__--- Cait- CostI--e A
;Tal Cos tCs__ Cost per Acre
Metcalf & Eddy
The total construction cost
areas $5,585,486 at today's prices.
given by,.Metcalf & Eddy for the
Our proposal involves an additional
pumping station and approximately 10,000 ft. of trunk line. The justifi-
cation for the addition is primarily that.sewage.effluent should not be.
discharged on the North Western coast in the.vicinity of the Buccoo
r ,'',.1 : .' L .
.. ,' ,I I j i I ll' I ; I, I' ; I l [
CONST-:UC'ON COSTS Conrd,
in addition zo otecti3 th.e Reef ou: proposal opens
to -pblic saweraae the whole -ara _otween 3uccoo and Canaan. We
have therefore sizc the systo::. t handle an additional ten
thousand (10,00G) people.
-V. s~y'~ ;~';...
,In te areas concernedA, anmbe of Hotels are at
present being consructed an.d oth-s planned for construction in
;ne near future.. T.'re is also large housing project now being
started by the Tationa... usi.'i Athority in the Canaan district.
Consequently t"he need. for a cent-alized sewerage system is becoming
We have already started designing and estimate com-
pletion of construction around June 1973, if construction starts
irAmeeiately after desin-co.pletion. Connections for most of the Hotels
and the. NHA project will be required almost immediately and 'certainly ,,
before the end of 1973.
With this in mind, we wish to recommend that the entire
sewerage project-be done'in stages in three contracts, in order
of priority -
.. .. .............. .. .. ........ .. ......... ...... '. .. .... .. .
(1) -reatnent Plant;
(2) Trunx lines, Pping Station'and Force main;
Although the total design population is 35,000, we
recommend that treatment facilities be constructed immediately for
a total of 20,000 population and the facilities for the remaining
15,000 be added in the next 10 15 years. This will offer little
problem particularly because of the type of facilities proposed.
C02~STI~JC~2ICX ?~0Ck~Q2/.J~ 0z~r.~ c?~.
Triuk lines are not easily expandable, so it is recommended that
they be construct initially for the total desi. life. The
laterals a y be deszsiLed now b1t we recommend that construction
be phased out as the developmnen dictates.
The following are very preliminary estimates of the
three proposed contracts.:-
(1) Treatment Plant for 20,000 ......
S(2) Trunk Line, PuLping Stations
and Force Mains .........
(3) Laterals .........
The possibility of breaking down item (2)
contracts exists. One for pu=ping stations and one
for trunk line
It should be pointed out that the ,figure at (1) above
represents the cost of a treatment plant with an initial capacity
for 20,000 people as opposed to that mentioned in the cost tabula-
tion which is for a plant to serve the future design population of
IoC connections to the sewerage scheme can be made unless
the Treatment Plans, trunk lines and pumping station are completed
So that Hotel Development is not delayed, we recommend
that each Hotel Development includes temporary facilities in the.
form of packaged removable plants to serve Hotels planned for com-
pletion before 1973.
These units should be of convenient size and be located
at strategic points with collection systems so designed as to permit
i :': .. 1 ? .i 1; i .. !I ; i I : i ; : .,: I .;; ; .. ,. '
easy connection to the public system.
Package type Treatment Plant units cost approximately
$300.00 per hotel room. Since these units will be for temporary use
they can be either rented or alternatively bought and shifted to new
locations as the need arises. In the case of hotels whose completion
dates will be in close proximity to the completion of the Scheme
rental of the units is feasible.
Units are available in sizes to serve hotels of 100, 75,
50 or less rooms. However, in view of the fact that the largest
planned hotel is 350 rooms, we recommend that a convenient size unit I
to serve a 100 room hotel be adopted as a standard. used in multiples
of this basic size to accommodate larger hotels.
TEMPORARY FACILITIES Cont 'd:
We would like to suggest that the collection systems
of hotels to be built be designed in keeping with the general lay-
out of the main sewerage system recosaended in this report. We
would also suggest that design plans of systems for such hotels be
referred to us for comments and suggestions before final approval
is given by the Ministry of Planning and Development.
ATTAS ard D- FOUR
LOCATTCN OF SEWER OUTFALLS
(i) T~here i a severe shortage of meaSurEmcts of currents
Soff the csct of T'obao.
(ii) .A thoo'rotical ap ocah to tho dete'ixnation of ourraat
has rcvoalcd .a oa.~te'sivo wJke system, with Oresultant t
low nrct movc'.t of r ff ;ie Toba Go o-C.i ooas*'t.,
(iii) .Available .for.tior, o0'1 heo ecology of Zu-ccoo Reef is
(iv) it is -ecoQmcaeO that no sewer outfall be sited in
Little Cou;i.ad 3Bay -
iramcdiatly coaouh of OxCist Point 6d off thei south-
wastorz aot ..e..ity of eti-it T.'ou.
(Vi) A oho r pzio aoc of float a dyo dstuioz should bo
carried ou C beforone doecidi on he n onf s zower out-
aO JA... ......... "t 0"? '
1.1. A p-'olainslr^-y -oport propered for the 7/ater aad Seweraeo
Automity contairsd propo;l of scwc- .Qe t.retme.t plaits o, Toba-go.
The repoo- sugestci til.t s er out-falls i Zittle Cou-lada Bay, close
to Booby Doir-t, acl 3:. :l ord 0:y close to C-vrn Point.
1.2. I-owvor- ScrJ were m0ossed that- 1the discharge of waste
efflue-t in coCo o :i-.iy to auccoo 20.o' was likoly to cause ohzaes
in *tho ecology of tc v2cX Z^- view of tho iportnrce of tho Luccoo
20ef 3y-Cystie a, a l-; .oral hezitagc: ii 3 conBsiceLd necessary to pIova
conclusively ,hcthe-r or .lot the outf-iallt of isewc".oag effluet aoar tihe
Reef will lJave advefa o effects o th'ae 2eof.
1.3. Iowove, toe timetable for constoticon of the scwer.ae
faci ies dii d iot allow c adcquato tiie for the extensive studies, of raef
ecoloyr acr wator ..vcacat which ould be required to give a conclutivo
c.4. Cocnseuc.ntly, the following appzoaches were adopted i-
(i) Collction of ll avaabl iforatioa o n sor
S(ii) Z ;iuzsi -. witl fisreran and other on water moveaa4
ir, tc ^ci-ity of 32soo0 eS .
(.iii) Colle- of Av l io io o ocean current
off tho coQtO ci' Trintai L ad -obcGo.
(iv) heootical ect.curn.ato- of -oe flow pattern for
thCe f 2low of ooSm tcurrets close to Tobaso.
(v) Dtrci;^a;tion o tiid.l curet in th vicinity o.
C)rov; a oi... "- i a u-cco Ro o..
(vi Cor...... of th rae. ls of theo tihorotical approach vwith
all vc..blo i-f ion obtino as at 1,4 (i) and (ii)
aboveI, ad lrvioh; r;casloc3aeiv; uaken offQ tho west coast oc
2. ,,.L, R TA* ;'
2.1. ihcro is za portage of reliable ear-zhoro cur~e.t data
off the coast of Tobgo.
2.2. In hias letter oi tria" itisal. dated 28th July 1970n Mr. Carl
De Pour stated -
"p. zprI)iinSy report has already boon preparcc by another
conui.tinr ; fiim in vhich proposals wverea m~de to disoh2ic tuhe
offlu.ca.t from the luccoo vaste trsatmcnt plant appro:cimat.iy two'0
oilos cc`rt o,; t Lho 2ccoo RePc on tho iorth Coast of tho Islaad,
*' oth- c ac' a..d absurface float studios were made and the
cu rrc- i;n both'- caseo carried the floatc out to sea,"
It isc zittr oSod that thc float studios took place off
Cromva oint ad Luccoo 2eeof but tho results of these -moazure"entos were
u rvailablo to "tAo rter..
2.5. It /was r=porte that thoe oods ole Occa o noapic Vessel.
Atl-atic II had "ta'cn. c2ome currcasz t Ocfasure.ts off tioe obao coast iL0
1970O. ae ce tsvdork could 4ot be tr and o rcpo;ctea to bo
;ot yet available in the "erritoy.
11.0. Publication 22 (156) reports as follovmz-
"Th tidal currents in the vicinity of Tobago are variable
and woe-c. The flood tidal currents acLcolorato -ie northw'esc ely
sts and tho .bb tidal currents slightly retard them causing a
cocsation for :,. short ti-i. 2he set is usually northwostwar
at a co"ncic:-alc rate however,
--Ith .... .o. cj 0the si outhoc.st going tidal current,
dcaiAS it2$ s2tr-.e-ith z .O.lo arD C 2i ? Oit forl about 2 hours
just chccld:ig or divertl? t"he northwest goins current. INear the
coaCt dud:c--,' th- rii i..o sli lrt oddy sets eastward into GrCoat
Cour-lacd 4ay, Sto0 i.Ea. an Id.-itlo Courland Bay. During the
fallir' tidLe 0t.Lher is a set ii the opposite cirectOion which soietinos
attis a rcatao of2 1 siot ioear Buccoo, eeef."
2.5. Discussions .it. .isheo Vwre ;tco luaive, wbut iiiilcated
a confu:sed stc= of cuaeints oa thl rorth coast betw eea Buccoo Point
2.6. .Duii-G S6p.tcber 153 th, vWiter ca=rized oilu somoe preliriay.
dy tcsts off St;co oay,. 3ye zroeased in about 20 feet of water remained
tatio azy .o svc-'a hoC's. Iter ia tho day dyae leased close to
hore., on tlh^ ."a tie was carriLod out to sea. uLjozrtufately aothe
detailed studios .w.r wl ot carz'0cd out.
.: i :: ; ,' .L ; ; :l i ,^ i 1 1 ;,: 1. ,; 1'
2.7. C ho above ino 'tio i a too sketchy to fozm the basis for
a considered opinrioZ., Howevezy t hey can sovoe to compare vwth the rcu ltz
.y -y: n% z;r0 R ..
3.1. IDetailed cooparisone of Zuccoo Reef over large periods of
time are not available. Howv'er, prolimmiary coparilsons of aerial photo-
graphs ir.dicato tho possibility that auccoo Reef may be grovd.4T eastward
5.2. he bathy.zctry.co the .sco bottom around Tobago is shown to a
zoale of 1:75,000 oz ."_cra'phc chart 505, which is essentially based
on a y.rosrapic u y carried out by H.l. Surveyix- Ship Vidal between
1957 r-d 1955.
5.o. T Io at ty of t a. bo-tto between Pigeoa P.oit and
youth ao to l of 1 :25000 on Admrlty Hydroap hc Cart
503. 2hLs is ssc.tially based on, a hy apic avey c out i
4, 00: CT ''' CI S COASTS, O C TIITIDAD & TOBACGO
4.1 *2 coco cuet off Iinidacl aad Qoago origLa=te in
th oth ril .c systca. hs cuent 3 gene.-ally sot noxih-
westwvr, .. are fairly zedy v velooitiezs fluctuating between. 1.0
ard 1.4 not's" (;~'oft ('iO~)) '''
4.2. Bertwent Tobag'.o a Barbados the curreats usually set
norhwpstiwardi at &-tes of 1 to .2 iacts, bu~t i May to July, rates of 2
to 5 lmota hvebeca. recorded. /1.0. Publn. 22 (i9637
4.5. The velocity of eth curre:.t betweca C2:linidad aid Tobago
varies from two to foux Ishot s /iH.0. Public. 22 (.196S57
4.4. "hes Sou... "quatorial currcrt flows in a pzedominantly
ni3 orth-wea't; ly'di.ot ion. 'I^s rdte is ^ally up to aboua 3 o losteoC
but on striki CC o .o it d-ivides locally Cad passes the north east=
Ctrc y'of tho i(-d..at a rate ofi 5 to 4 foi AdnAiralty Hydro-
paphic Chart 503 (997 :.
*5. T RcaI Ot L.: ..1;.IC3,ic rg OCI0 T cuJiRT'T s'StiP
5.1 Oce coo coastline of rndad d.
Totco ol ito i t'. SouZ ~t C.. utoria Cu'ret tat isti cal data
on this c et as f 0. a. ub. (n. 700 (1965) is presented
on ths 0u %' % asoz.M'':&oJod zo'-
in. Table below.
.A732 1 00C 0 C7.-.. 0 037O T O-1rGO
S3. ,:::'^ (Jo mar- ) SummP (Jul-Sopt)
Direction on Otha. X.VI W7 Other
SOccu)Cce (); 0 50 30 20 50 20 ~ 0
Av. 1C.r;C Z Speed (:ta.) 5 1.2 0.3 1.1 0.9 0.7
5.2. TZ1 isle d of riiriicad .a onr.y minor offects on ocoaa curr~cni
in the vicia=ty of 'obao. The islai oi' Tobago las stooply clopir. zsideo
a- closely app~o:i;- s r.s aln lliptical cbjoc' oo stand on tlho floor of a
deep ocean. :ay epeivCants have oae. carried out (by bydodynaamcists
"ad acrody1iai cist) on.iC pasCtoL0 of flow around zscoli au obstiuctio.
lyias in toi" pcth of a uifor flowi, Uiifo. rancltly all ite oxporimntal
a nd heoo --ti1cal wIo~ ~s boon ccria.o out on very o call models.
5.>. Howv utI. thae -oalta of the experiment aad theory,
t-pamirecs ,IeQa fo-.: for current direction tot~ west antd to the norZi-
weotz, uvsirz a velocity of 1 lawo-a,. Tese.o tiroaalin.es a"e shown0A oa ireiS
1 ard 2 rosp actively.
5.4. Tho o act .~atuC i0 e of th ur wa e e cxpoe iencoad ina th lee
of t lue isl a. is not co-ri as aa orct. aivo sea-ch duid not p.oduceo a-
pc ital esult on tZ. -aUre of t~e wkR eoxpio-naocd at Reyiaolds oas.
as hih a. t0ho o iWnvolved- in "Lis caso. s Vor' by onxy (1963) off the
vest coast of Ba sdo3 has howeverv indicated the probability that at voIy-
hil values of .2cy..olds Io. a systmc of voices are shod alra-tivoely
in tho wakO, in uc thle came n:^ o as tho woll k3aow"A VSa CKa.n=I Vortow c
t o at leC values of 2 old No. y (1955) also
eared rat of water ov of locs t chan 500 ft per day in this vwake
syztcmz as against 20 ;iles per day in the main current stream.
5.5. 2irse 'i ......s t'h; ,h .i;. -- current is flow'in in a westerly
direction a sall l w: is f-crz-o oC t'C n- o ccaCt betwoon plyouth. san~
Crov; oint. tr o-/ --t in ithe we is eeted to bo vo-y low.
Smaller eddies are -xecxe&l to troc: off -heLin coddies and circulate in
Little Courlard, St onel~avr C=d -Gra'; o'Jl.lad Bay". Te net vwate movo-:
monti; duo to ocoCaric ci.rrc.t. i. i bay, ee bcs is expected to be veoy low,: j
5.6. PiuL o 2 o':- tat w.en t 0o oceic n fw in a nrh-
a'sVern dicc=co, poizo', of paration ill fom off Cov oin ad
tho extreme 0ora'-caa.tom tip of obzao, It also deaonsitrateaa the fo:iaticn
of a very lar flcoa.in wae yci off to en-ire norta coast. TVho
viwao sytca will aain e0 I nerate very slow moving eddies in Li.ttile Cou.Iland
C-rea CourlanCd and Sos Sr ay s.
6. :.,.".": AL ....... i '"'' O Ct OP TI A .L CU 2 i S1YS.3 ,
6.1. 'ohe tide pro~acsses past Tobago in a south-oastorly di ctlion.
This givc rise t-o tidal c-rronts, which can be represontod in the open' csa
by a curron- ellipsZe Vwth -th vector fon the centre of the ellipes
reprcs0ontiz the railtdeZ aLid diction of the t tidal current. Thls- in a
tial cycle t: ect tr po r of particle, due to the tidal current ic.
6.2. Concic ab dictc tic o the, magnitude and direction of the
tidal. current i caced by coc tal co iGr>ation. .The corrospondig nath-
a4.tical tr 2cn~e-- is voez complicated ad time consuming~ but -roudman
F1[.-~ 0U Tf I:_ ~ZL cC ~3C
C, AA\. Dc.
b a- N
'---' C .- ;- .c
N SC IC :t jC Lo~'c-
a* a rei I:t .-;'.... r'_ r.'.i a -rf_. ." j' :.s:r r
rcval of .ye s.i t outf to e, cas be eJplain:d by the tidal currG-t
vhich in. t p...d.ity of Co- 2o ill flow 1o pedonmiaatl1y il a
cou2-2as;torly direc~tioc at; flood tide adS, a no:h-weeerly diZirecaion" ai;
7.5. he za.;it-ude ca- di action of the ti al current of: C0zA
Point ca predicted by parc 6,3 is n'Ct enough to checa theo oceanic
currnCtr a; flood ti. (ce papa 2.4).
7.6. h1e occu-.^c cuVrre-rct th0eoozry predi.'cts sligh eddlio of vayi-j
di'ec-;ion. ctoria Gcat Cc'ulca,- Stor.elaven a=d Little Cour=lad Bays.
In addition. total curt thaeory spo-ts th co.cpt C water catexi
these bays at flood tide and leain- them i fallt, tide. Zhe t*dal
a crrat is cxCpcted to be stong.e thnia the oceani cCurreat with the ;;,
.ecult'g p3doir.ace of theo tidal "att ". of eddioz mctioned ia paia.
7.7. Th boy b between. Bcoby Pointc and Plymou-th are all shallow
bays anid concouc:,ntly ti-dal caurent velocities arc not high. However
Buccoo lay is a do bc.y vLth a ra r re.tricted =trce (see Hydogaphic
C"i; 508). Consco5u03;ly, tidal cu"i'^d volocitieflj in ho channels
opeiC AU to ZBucoo Lay a:-'oeo ted to be higher tb.zha currents enter
the other bays on: th- orth. Coast. This probably accounts for the rate
of 1 loi; e.oar .uCoco ,c1 quoted ii. para *24. .
C8 :* -::. *- :* .uESAL T'. 1 EMI OLOCG 6O '00CCCO RI5E'
8.1. U~:'fo.rtu;i:olyo vey little i- oown about *hie ecology of
Buccoo co. Hovor, it is l n- -.ow. -at capepods ,vich aro ca import i
roval o y si t, out o :eaca, b o:lainod by the idal curr
which in the pro zity o.' Cro-a 2or w'ill flow pe'odo ttly iLa a
coutli-oac.torly directicr a' flood io e at d a nori.-j-we~' disectlion a'
7.5.. T'he ii c motion of the ti ourrnt aoZf O Cx a
2oint as predicted by para 6.3 is st-rong aou t hto cCheca t.h oceanic
cuzrrt at flood tido (eco pa 2.4) .
7.6. T~2 occc0 crt.rct heozy pr? ficts slight c8dioe of rvajriy'
direclwiorn c!torin C t Oc'LN lsd S-on- CIavea ed Lis-tlse Courlzad Bays.
In ad0ditioxr total cu-rr,,n teo s-^pp ts o coccpt oZ vater eateoi
ti.ese bays a flood "tide ard leaIre them at fallen tido. h.a tidal .
currea is cpoc-d o be stony. tlia the oceanlc curmi. Vwith th o ,
reTult~ng predo~ace of theo idal pattowa of eddio- mca=ioaed i~ para.
7.7. 1.ho boys bet-iycv Booby Poizt ad PlyZouwth are all shailoc
b.ya ad QconVccucattl *i' l ourr'in' velocities ayr *ot high. However,
Bucc-oo Lay is a cdoc y :.la ra r ores tricted aitraeoo (soe Hydrogplhio
Cha-T 508). Co ,e-tly-- tidal curocat velo ties in the channels
operian to aBuccco Z, y aro e:e Cted to be higher than currentze te~r-in "
the otheo- bay/oon "-e z orth Coast. This probably accounts aor the rate
of 1 -lot noar Succco Lc2 cuotod i para 24 "
I8. Ir.n0T TE23GSA.L D 0 ECOLOGY O 0J0000CCO R.35
0,~.------------------~- .i-- -- .~-rl--- r~---~
3.1. Ui'ort- .:-oly, v:ey little ic i=-own about the ocolo&y of
Luccoo 2cof. Howov- r, it is aeovoa t-..t. capepods ich o ar
Taw) tiat for a a iwoular ONE SO0i:~ ic~l ~ vortival chores the~Z
";n.-:.ral Sk~or on bth SWOO azond the izzad than Say th
AV: 210u'. lma vaLes ioz fo a COCA= islap tidal.
ACP voter ma 00 vicinityoof Po.ow vtould be ex-paatcd
to fax -out a:' "loodtidc; ad, th O&Wud a eb, atta~,inimac
=C~ziLu VzuaeOs OA 0' knon at doe. The veJocitV of the tidal
Oclczzt J.;ld be 0c4vso to a:ez; ,o at ., Wa ooaztli.ne.
7.h1o reozutanIt ".7/ n SYMSC.? Oz the coasts of Tobago is
cav.zd by a cOStL n. c12 tan ooc.anaio an.d. Wial. cuaredt pyatcsa dWoz bod
in paxacr;s 6/ v 1 vivw of the qualitative aturo of the
thia-cia at bbst a qualitative picture oaa be, obtained.,
7.2. /hC IO-.'din toz~thiae!:' of thr. atc as 'a--ey pa.z -ho
Cantmaaad ;'; stann anaz" s cf fajo (ozeo Pi~z. 1 and 2) will. result.L
zoa. 12..) s roe: i"th vaJucz caotce. ia pamncrapih 4.2 to 4.40 az'con.-
trazsto wi value,-, i c oca;. wan c quoted in paai'axphs 4.1 cnd 5.1.
It it :L r.-,)t 1=0%zr. at lah depths oz at Vint
z600e 01 t0e0 too fZloat tOS rs ~erred to, W PaXIGaph1 2.2 wivo ckixiem
out. Caso eqetny this izesul p ofi litte valtue.
7.4. of c ocd in. paz 2.6 caa be b a i. coa
by th ve;J z v';- :z:ozt0::c cn :La 4,he wao. .oeCrah'o hon. l
food i'c" ca. i :e ^c1ou lly uit cucdat ia: loos. Co .sequez.tly,
th1e ecclay 32 on Lo o A cod Ica c ooo 2ay pc bably have cosiBeybaablo
iluecs on toe oi colo cc
the ocs a i n0 e bet i.'ie ocr. Io-i=t "ad Roc2:y Poir-t, plaSnktonan. ate:ial
wo-culd tc;i 1-to acc:.ulzto i-i the vicinity of tho reef,' Th tendenCcy to
cccru.ct ec.... t....e -oof' is aocCtu'tcd by ith high tidl velocdtiec ;x-
--pectcd in t-U13 vicinity of ccoo C eC2 dueo. to *tOh filling a aad e3pt2ip a of
8.3. Soce of the offlent diZschi-rged near Booby Point vill ertcr
Buccoo Bay becau=cC of theI sya"s. of e-ddies, Caxd -tLe ti-dal currents .-:i.
.ad. "fillinG. "Duccoo Bay ... .-ity 'of flet %hi'di wi llate tLo y
canota1ootimbed wiAtt^'icir v a '; "' '" '' ". '"
8.4. Although t' icffl'.ueOt will be treated, it will till contain
hi co -ntioations of copmpoucds of pho ,aorous znd nitrog. These
detorimincd by tho phosphItd to itate iatio' the discharexof taho off'iont
oouald un foz;t-eately cl2--i- :ho natural b1ala;co of tae phytoplantoa
conditol s co ud jlo-t .tho .food ohin ir a m-nr, +detr-~cntal to the ecology
a.5. .-Io..-iore, if th waste adisch o ca-c d a large in o.
ia -he &conzcc'ttio.1 of phoQphor2 ad r.it-oen, con.sid;oraxble chaceo i.
ec ':"it could c:'..- j.-e e.ytoplato blooms could become so
daCo as t. o =", ob, tio''" abl; fr .- reational atadpoint, d pei.odzs
of ci-off .culd produce eci- o:G depletion c the water,. It dhoul
bo poiedL ou.t tSa dich heir grow-t haa.3 occurred around the outfall froa
a sce 37 pl. or a ro0oL i .-a bados that very heavy aa'ial X'enditi'u'o
ol maintcisico is a ;volve* i*. tio case of the Buccoo cover outfall this
grovrit could eC;c:~. i-nt c Ctio o0 f Btucooo Bay and the roef area, ad
also covo- octio- of Li -tte Courlas a Bay, v ich is scheduled for fairly
heavy reicreatioal uco.
9 C* -" '"_
9... '-1e thcore-tical apoach to the currict system around
'obao povi.co. a satisfactory c .1itative a.seszsnont of tlh currt '
d.u'CZ'.i. A orc doetailed'no owlcd&ge of the curo t; system car only be
cj.in.ed by .. ..ll- l.-c.c. zcoyze of moasurmaits9 supp.lemnoatea by. a.
,92. "' "watr rovc.a-i; o'f t-ho etire north coast is expected
to0 b1o vOryy all for rc.od.-tely '50 per cta1 of the tilmo duo to tho
'uimation of a l. e tir'bulonat w ai;c ~cystcaC bohindtei islaZid, vwcn the
occe.ic cu-rJt i" oin in a ior's,-westcrly "iirectio- .
9.5. 1.,, 7t vato ivoet off ~ta coast betwelN Plymouth aad
Pigeon 2oinit i e-ected. to bo vowy -low for moro thsa 75 per cont of the1,
9.4. Iih rate of cur t_ vloci-y aocd ret water Porvemeit .illI
be e::poetod to occur c., the ou the' z iz o.f CrovmN Point, .just uptra.'
of the se'aratioa. pc-.
39.. So0c2 of o-a cz:.lnt di^scargd off uccoo oiSt ThL fcicL
its "wsy into chcoo 22-" .. "' o c --" i; of ef.lucv f-idia i.s ..7 i-no
3uccoo 32y iz li-y i' cca -'al1 i-. ci-x:o of he phyople:ric .cs
,pr..odod.iatin,.O, .ri;h -?lLi c2.aLion o" to foocL cyclc. .his change '"
j;;^ produce cdol8 o uo^ou3 cef.^e^ct o^. tho roo*. U 7Lotimately, toe jixor.-^-
a"-ion on ecojlogr is in?-icice 0 to Sive- c, mor'a iOfiiait! o .aver.
9.7. .s not woxvcac in close. p..o:"lt-y "to ithe ro f ic
.ot vozy hig, dcacZ .c 0' the o~fluc-~t ;:a-j Booby 2o".t could ros'lt.
in t- ho fo.ua'ticn of ds; ph1y3opl 0l-toa blooms i iittlo CouL'lcaci L y
ar*dl the r^ w 'lse ow/hs v.ill bel;c doetzim'al to booscriat.io.:.tlal
us.; of. 0': -s.1
O.1 v- of -e hih probability of onaiodeble ecological
c Zarees aro'c.x 1,cco Z2 3uccoo By cl Lit-tle Courli-nd Bay, it io /
recoedc 'a tht n; o cor cu A. "".ll bo sited ^i Zittle Cou laad Bay..
10.2. Prom theo pott of vicw of cO' ts .-the entire south coast
betwoca ioovlands 2Poit L~o~ ^ o. is c-i. -blo- Tor lo cat.ca
a sowe ouall. Jover .Ciof Qh1 cos, las vy t; osore
slopes. t is thcrofoi-e rco l that -th scwo outfall be siteii /
oit1her on the south si e of C-ov oint or oin theo csouth-westios oairity
of I etvit IIou.
o ... .... ... . . : ..^...
10.. ', .,, It ip -co:sgaedltil:2 a hoL -pira of flo.. e..., "..
o'aos. be cca-.rrie out- before decIdinz o0 the lenUCh of ewer outfall.
--1. r ;
(160O) "aysziccal Oceanography" P1crgaon lPreas
(1350) I"A. Tpoti or. the Investigation of Coastal
Curracns in the vicLnity of 3arbados" Bellairs
2aoachd "L~s.Itu.'o o.. McG-ill Univezsity
2 T J (1925) "On tidval features of local coastal o:'iaia
and 0.1 sea seiche or Noa Rot. Asty. Soc. Geopbys.
Suppl. I ITo G., p.247.
H.S., c j- "OI9- 0:I- GI'CE (1955) Sailing Diroctionz for the
Wes-1 Indicos Vol. II". 11.0. Pub. Xo. 22
S.,S,, VX Q 02OCAO o" 0 '0 (1 i ..5) -, "Oceanoraph-ic Atlas of the
Sorth Atlantic Ocean Soctio" I 2ides a.& CureC t
.0O. dub. INo. 700.
/IA one ; a wiA f l Sd I At
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