How To Inspect
Underground
Storage Tanks
Petroleum Storage
Tank Maintenance
WEBINAR: 12/18/2013
10:00 -11:15 am CST
Environmental Compliance for Petroleum Systems
Outline
PEI RP-900 and RP-1200 inspections
Fiberglass Tank Deflection Testing
Tank Cleaning & Water Removal Methods
Internal Video Inspections
PEI RP-900
Daily, Monthly, & Annual
Inspection Checklists
PEI RP-900: Daily Checklist
Leak Detection
ATG functional & no alarms
Daily Inventory
No Complaints (Slow-Flow)
Tank Area
Fill cover
Spill bucket (clean & dry)
Fill pipe
Dont forget dispensing equipment.
PEI RP-900: Monthly Checklist
Leak Detection Method
ATG passing tests
SIR passing tests
Other methods - passing
Tank Equipment
Manholes
Spill containers
Drop tubes
Tank stick
Check for water
Vents
Vapor Recovery
Wells
Corrosion Protection
PEI RP-900: Annual Checklist
STP Inspection
Test Line Leak Detection
Check for leaks
Sump Inspection
Condition
Product or Water
Test Sensors
Inspection normally
conducted by certified
technician
PEI RP-1200
Methods for checking
Spill & Overfill Systems
Leak Detection Equipment
Secondary Containment
EPA Guidance
EPA Checklists
Release Detection
Spill Protection
Overfill Protection
Corrosion Protection
Deflection Testing Fiberglass Tanks
Fiberglass tanks became popular in 1970s
Some 30 40 year old tanks are still in service
Tanks may deflect or deform over time
Many potential causes of structural deformation and/or deflection
Poor installation practices
Poor compaction; substandard backfill; migration of backfill
Voids or air pockets; lack of support in critical areas
Softening of fiberglass resin due to fuel additives
Many new additives that tanks may not be designed to handle
Alcohol/Ethanol/Other blends may impact older tanks
Other Heavy Load Factors
Excessive traffic loads (tanker trucks)
High water table
Damaged tank pad or construction activity
Example of Fiberglass Tank Deflection
EXAMPLE OF STRUCTURAL DEFORMATION AND BOTTOM FLATNESS
CROSS-SECTION VIEW OF UNDERGROUND STORAGE TANKS
Tank shell has
round crosssection and normal
stress loads
Measures the
sector which is
the distance from
a 24 chord to the
bottom of the tank
Tank shell
suffers from
excessive
stress due to
deformation
"NORMAL" Tank
"BAD" Tank
DEFLECTED
TANK
92" Diameter
90" Diameter
Original
92
Diameter
1.1" Distance
1.6" Distance
24" CHORD
Methods To Detect Deformation
Vertical Deflection Measurement (tank diameter)
Normally measured during installation part of checklist
Should compare diameter before and after backfilling
Not a reliable indicator for existing tanks
Original diameter usually not available for comparison
Bottom Flatness Test (Tanknology Level I inspection)
Better indicator of tank deflection than diameter measurement alone
Most cost--effective and accurate method for multiple tanks
Requires proprietary tool and expertise
Internal Video Inspection (Tanknology Level II inspection)
Provides visual observation of possible deformation and bottom flatness
May also show blistering, deterioration, stress cracks, buckling, etc.
Tank must be empty
Manned Tank Entry
Measurements of deflection, bottom flatness, and hardness
Costly and potentially dangerous
Bottom Flatness Testing - Setup
Digital
Caliper
Insert
through
standard
4 riser.
Tank Cleaning Methods (1 of 2)
Bottom Sweep
Removal of water and/or debris from
bottom of tank using guided hoses.
Cim-Tek Cim-Cart, Gorman-Rupp
Tankleenor, Tanknology, others
Fuel Filtration or Fuel Polishing
Cyclones, Coalescer/Separators,
Filtration, Conditioning, etc. Establish
return flow of liquid to carry debris
toward inlet.
Algae-X, Tanknology FuelPure, others
Tank Cleaning Methods (2 of 2)
Rotational Pressure Washing or
Impingement Cleaning
Tank is empty. Spray Balls or Rotating Spray
Nozzles wash and rinse the entire tank.
Waste water and debris is pumped and/or
vacuumed from tank.
Butterworth, GamaJet, Spraying Systems
Video-Guided Pressure Washing
Spray nozzle cleans specific areas of tank.
Video camera monitors and directs cleaning
process. Vacuum out waste water and debris.
Tanknology TankClean
Internal Entry
Shovels, Scrapers, Brooms, Mops, etc
Video Inspections - Reasons
Verify and locate holes & cracks
Verify and locate water ingress
Fuel Contamination
Water bottoms
Cleaning operations
Corrosion inspections
Lining inspections
Condition of fiberglass tanks
Condition/presence of overfill protection
Operation of STPs and other equipment
Retrieval of dropped equipment
Identify available bungs for ATG installation
Water Ingress
Water ingress at
STP Riser
Small Water Ingress
Random inspection identified small water ingress
Water Ingress
Small water ingress through crack in tank
Water Ingress
Large water ingress through hole in tank bottom
Water Ingress
Large water ingress through hole in tank bottom
Water Ingress
Large water ingress
through STP Riser under
Containment Sump
Small Water Ingress
A tank failed the VacuTect test due to water ingress
The tank was taken out of service and sat idle for 6 mos.
Several inches of water and sludge accumulated
The tank was then pressure washed with TankClean
Small Water Ingress
After thorough cleaning the entire tank was visible
A small ingress was identified at bottom with TankCam
The hole had been clogged by sludge in tank
The water trickled in again after pressure cleaning
Water Bottoms
ULSD Tank with clear fuel but
sediment on tank surface
No water at Fill Pipe or ATG Riser
Clean sample collected
No history of water pump-outs
But a pool of water exists on tank
bottom between fill & ATG
Dark color indicates microbial
growth (confirmed by lab sample)
ATG
Striker
Plate
Drop
Tube
Fuel Contamination
Sediment and debris in bottom of tank
Looking down through 20 of gasoline
Fuel Contamination
Heavy sludge on tank bottom
Fuel Contamination
Heavy sludge on tank bottom
Fuel Contamination
Heavy sludge on tank bottom
Tank Cleaning Video Guided Wash
High-pressure TankClean water jet is directed toward
surfaces that need cleaning
Process is monitored with TankCam
Debris is pumped out with vacuum truck
Tank Cleaning Video Guided Wash
TankClean Process
Corrosion Inspection
STI-P3 tank.
Interior still shiny with no
signs of corrosion
Corrosion Inspection
Heavy corrosion in steel tank. Small water drip at ATG and
hole in end cap. History of water ingress and sludge.
Corrosion Inspection
ULSD systems have experienced corrosion inside tanks
Ball Float close-up
Corrosion Inspection
ULSD systems have experienced corrosion inside tanks
View down fill riser
STP shaft
Lining Inspection
Internal linings Good?
Lining Inspection
Internal lining. Sludge covers bottom of tank.
