Introduction
When an underground storage tank fails, whether through corrosion,
pinholes, stress fractures, or joint failures, the traditional response is
also the most expensive and disruptive one: full excavation.
Excavation means: removing the canopy, breaking up the concrete
forecourt, digging down to the tank level, extracting the old tank, installing
the new one, backfilling, and reconstructing the forecourt, all while your
station is completely out of operation. The total cost, including lost revenue
during the closure period, can easily reach ₦30–60 million or more for a
multi-tank station.
Non-excavation underground tank repair changes this equation entirely.
Using advanced internal lining and structural rehabilitation technologies,
tanks can be repaired, sealed, and returned to service, without breaking a
single square metre of your forecourt concrete.
Chess-T Group's underground works division delivers non-excavation tank
repair services for filling stations across Nigeria, using
international-standard materials and techniques that restore tank integrity and
extend service life by 15–20 years.
Industry Overview: The Scale of Tank Failure in
Nigeria
Nigeria's filling station sector contains a significant number of
underground storage tanks that are at or beyond their design service life. The
risk factors that drive tank deterioration in Nigerian conditions include:
Age of Infrastructure: A large portion of filling station USTs currently
in operation were installed in the 1980s and 1990s. Single-wall steel tanks
from this era were installed without cathodic protection, modern coating
systems, or secondary containment, and are now deteriorating.
Electrochemical Corrosion: Steel underground tanks corrode through
electrochemical reactions with the surrounding soil, particularly in the acidic
soils common across the Niger Delta region. Without cathodic protection, this
process accelerates significantly in moist conditions.
Physical Damage: Historical flooding, heavy vehicle loading across the
tank field area, and inadequate backfill material during original installation
can cause physical deformation of tank walls or fittings.
Fitting Failure: Many tank failures occur not in the tank body itself but
in the fittings, fill ports, dip tube connections, vent connections, and
product lines, where corrosion or mechanical failure creates leak paths.
The consequence of these failure mechanisms is a growing backlog of tanks
that need intervention but where owners are deterred from the cost and
disruption of full excavation.
Non-Excavation Repair Technologies
Chess-T Group deploys the following non-excavation repair technologies,
selected based on the specific failure mode, tank material, and operational
requirements of each site:
1.
Internal Structural Lining (Primary Method)
A structural resin lining system is applied to the interior of the tank
from the access manway. The process involves:
•
Product removal and tank cleaning to remove residues
and vapours
•
Surface preparation through mechanical abrasion
•
Application of multiple coats of structural epoxy or
glass-reinforced plastic (GRP) resin
•
Curing under controlled conditions
•
Final inspection including holiday testing and
thickness measurement
The cured lining seals all pinholes and corrosion points in the existing
steel tank wall, creates a chemically resistant interior surface, and provides
structural reinforcement that extends tank service life by 15–20 years. The
lining is chemically compatible with PMS, AGO, and other petroleum products.
2.
Flexible Liner Installation (Bladder Lining)
For tanks with more significant corrosion where epoxy application is not
suitable, a flexible plastic bladder is installed inside the existing tank. The
bladder provides a completely new product-contact surface within the existing
tank structure.
3.
Cathodic Protection System Installation
Where the primary failure mode is external corrosion, a cathodic
protection system is installed through existing tank access points. Sacrificial
magnesium or zinc anodes, or an impressed current system, is configured to halt
the electrochemical corrosion process without tank excavation.
4.
Piping Replacement
Product piping between tanks and dispensers is frequently the source of
product release, particularly for older rigid steel piping systems. Flexible
secondary-containment piping is installed through existing pipe trenches or
directional micro-trenching to replace corroded rigid lines.
5.
Fitting Replacement
Tank fill ports, dip tube fittings, and product outlet fittings can be
replaced or resealed without full tank excavation in most configurations.
The Non-Excavation Repair Process
Chess-T Group's non-excavation tank repair programme follows a structured
process:
Pre-Works Assessment: A comprehensive inspection of the tank interior
using CCTV camera and thickness measurement tools establishes the exact
condition and identifies all areas requiring repair.
Product Removal and Gas-Free Certification: The tank is emptied and purged to
achieve gas-free status. A certified gas-free certificate is issued before
entry work commences.
Interior Cleaning: High-pressure cleaning removes residual product,
sludge, scale, and corrosion products from the tank interior. Cleaning material
is disposed of in accordance with environmental regulations.
Surface Preparation: The interior surface is mechanically prepared to the
required cleanliness and profile for the selected lining system.
Lining Application: The structural lining system is applied in accordance
with manufacturer specifications, with each coat allowed to achieve minimum
cure before the next application.
Quality Inspection: The completed lining is inspected for thickness
uniformity and holiday tested (spark tested) to confirm that no pinholes or
thin spots remain in the applied coating.
Commissioning: The tank is approved for return to service, and a lining
certificate is issued for NMDPRA compliance purposes.
Regulatory Acceptance of Non-Excavation Repairs
Non-excavation tank repair is an internationally recognised remediation
methodology accepted by petroleum regulatory authorities in the United Kingdom,
United States, Europe, and South Africa, markets with significantly more
developed regulatory frameworks than Nigeria.
Chess-T Group works with NMDPRA's technical staff to ensure that our
non-excavation repair programme documentation meets the regulatory standards
required for the station's operating licence to remain valid following the
intervention.
Documentation provided includes:
•
Pre-works tank inspection report
•
Gas-free certificate
•
Lining material technical data sheets and compatibility
certificates
•
Application quality control records
•
Post-application holiday test certificate
•
Completed lining warranty certificate
Cost Comparison: Non-Excavation vs Full Excavation
The financial case for non-excavation repair is compelling:
Full excavation and tank replacement for a typical Nigerian filling
station (3–6 tanks):
•
Civil works (breaking forecourt, excavation, backfill,
reinstatement): ₦15–30 million
•
New tank supply and installation: ₦8–20 million
•
Lost revenue during closure (estimated 3–6 weeks):
₦5–15 million
•
NMDPRA re-approval: Additional time and cost
Total estimated cost: ₦28–65 million+
Non-excavation internal lining for the same 3–6 tanks:
•
Tank cleaning and preparation: ₦2–4 million
•
Lining application: ₦8–18 million
•
Station downtime: Minimal (often less than 7 days total
for all tanks)
Total estimated cost: ₦10–22 million
The typical saving is between ₦18 million and ₦43 million — plus the
value of weeks of uninterrupted trading that would otherwise be lost.
Frequently Asked Questions
Q: Is non-excavation repair as reliable as full tank replacement?
A: When executed correctly using appropriate materials and application
standards, internal lining provides 15–20 years of additional service life, comparable to a new tank installation in many cases.
Q: Can all types of underground tanks be repaired without excavation?
A: Most steel and fibreglass underground tanks can be repaired through
non-excavation techniques. The most important limiting factor is tank access
for interior working; tanks with very small manway openings may not be
accessible for lining application.
Q: Does the tank need to be taken completely out of service during
repair?
A: Yes. The tank to be repaired must be emptied, gas-freed, and taken out
of service for the duration of the repair works. However, other tanks on the
station can continue to operate throughout the process.
Q: How long does a non-excavation repair take per tank?
A: Typically 3–7 days per tank depending on the tank size, condition
severity, and selected lining system.
Conclusion
Non-excavation underground tank repair is the smart, economical
alternative to full excavation that Nigerian filling station operators have
been waiting for. It restores tank integrity, extends service life, eliminates
product loss risk, and does so at a fraction of the cost of traditional tank
replacement — without the devastating operational disruption of full forecourt
excavation.
If your station has ageing underground tanks showing signs of
deterioration — unexplained inventory losses, corrosion around fittings,
monitoring well product presence — contact Chess-T Group before you face an
emergency that forces the most expensive option.
Why Choose Chess-T Group Ltd
Chess-T Group is Nigeria's specialist in non-excavation underground tank
repair:
•
Internal tank inspection and condition assessment
•
Gas-free certification and environmental compliance
•
Structural epoxy and GRP lining application
•
Flexible bladder lining systems
•
Cathodic protection installation
•
Product piping replacement
•
Full regulatory documentation package
•
NMDPRA compliance support
We repair tanks without breaking your business.
Planning a filling station project, LPG plant, automation upgrade,
compliance registration, bulk fuel supply arrangement, real estate development,
or outdoor advertising campaign? Chess-T Group Ltd provides professional
end-to-end solutions across Nigeria.
Phone: 08143449981 |
08188076267
Website: chesstgroup.com.ng
Email:
chesstgroup@gmail.com | info@chesstgroup.com.ng
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Chess-T Group Ltd —
Building Perfection
