Skip to Main Content
Table 2

Main sewer lines failures at several streets in downtown Port of Spain

Failure root causeaQuantityFailure categorybFailure modec
Sediment accumulation 200 Hydraulic restrictiond SSO 
Dumping of FOG by restaurants 113 Hydraulic restriction SSO 
Severale 63f Severalg Offensive odor 
severalh 45 Reduction in hydraulic capacity SSO 
Dumping of foreign objects 39 Hydraulic restriction SSO 
Environmental conditions/temperature/unprotected surfacef 20 N/Ai Manhole seating corroded 
Environmental conditions/temperature/unprotected surfacef 16 N/Ai Manhole cylinders corroded 
Severalj 15 Structural failure Cavity on roadway 
Pipe sags 12 Hydraulic restriction SSO 
Environmental conditions/temperature/unprotected surfacef 11 N/Ai Manhole rungs corroded 
Environmental conditions/temperature/unprotected surfacef 11 N/Ai Manhole invert corroded 
Leaking sewer joint 07 Hydraulic restriction SSO 
Severalk 07 N/Ai Manhole invert poorly constructed 
Root intrusion 04 Hydraulic restriction SSO 
Theft 04 N/Ai Manhole frame and cover absent 
Failure root causeaQuantityFailure categorybFailure modec
Sediment accumulation 200 Hydraulic restrictiond SSO 
Dumping of FOG by restaurants 113 Hydraulic restriction SSO 
Severale 63f Severalg Offensive odor 
severalh 45 Reduction in hydraulic capacity SSO 
Dumping of foreign objects 39 Hydraulic restriction SSO 
Environmental conditions/temperature/unprotected surfacef 20 N/Ai Manhole seating corroded 
Environmental conditions/temperature/unprotected surfacef 16 N/Ai Manhole cylinders corroded 
Severalj 15 Structural failure Cavity on roadway 
Pipe sags 12 Hydraulic restriction SSO 
Environmental conditions/temperature/unprotected surfacef 11 N/Ai Manhole rungs corroded 
Environmental conditions/temperature/unprotected surfacef 11 N/Ai Manhole invert corroded 
Leaking sewer joint 07 Hydraulic restriction SSO 
Severalk 07 N/Ai Manhole invert poorly constructed 
Root intrusion 04 Hydraulic restriction SSO 
Theft 04 N/Ai Manhole frame and cover absent 

aThe origin/primary failure cause.

bThe failure that a root cause provokes.

cThe end result/consequence of a (category) failure.

dHydraulic restrictions are more commonly referred to as blockages.

eMay include sediment accumulation and dumping of FOG, among others.

f49 failures categorized hydraulic restrictions; the rest (14) categorized as either absence of ventilation or improper or insufficient ventilation. Thus, in this table, the 49 hydraulic restrictions for offensive odor are subtracted from the total number of failures during the 3-year period (about 520).

gMay include hydraulic restrictions, absence of ventilation, or improper/insufficient ventilation.

hMay be due to excessive inflow or infiltration, pipe deformation or inadequate slope.

iNot applicable.

jMay include cracks or fractures along the wall of the sewer main, misaligned or offset sewer joints, poorly constructed WWCS, deterioration of sewer main due to internal/external surface material loss.

kMay include absence of standardized design and construction specifications, inadequate training of wastewater personnel.

Close Modal

or Create an Account

Close Modal
Close Modal