7/11/2002THH\AST\FSS2002.PPT 1
Alternatives to Secondary
Containment Lining
Tarik Hadj-Hamou
Phil Myers
Thierry Sanglerat
GeoSyntec Consultants
Freshwater Spills Symposium
Cleveland - 19-21 March 2002
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Statistics
500,000 AST Facilities1.8 Million ASTs80% Without Low-Permeability SecondaryContainment
500,000 AST Facilities 1.8 Million ASTs 80% Without Low-Permeability SecondaryContainment
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Bottom Release
Overfill
EquipmentLeaks
CatastrophicFailure
AST Releases
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Pinhole
Secondary Containment
Purpose Is toControl, Contain aSpill Until Clean-up
Historically, ConcernHas Been Lateral Spreading of Spill
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Secondary Containment
Design Concerns Provide AdequateVolume (largest tankplus precipitation)
Allow Operation andMaintenance
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Regulations/Guidance
Federal Oil Pollutions Act of 1990 Amends
Clean Water Act 311 40 CFR 110 - Discharge of Oil 40 CFR 112 - Oil Pollution Prevention
National Fire Code (NFPA 30)
States Departments of Environmental
Protection, Quality
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Federal
40 CFR 112(e)(2)(ii): All bulk storage tank installationshould be constructed as that a secondary means of containmentis provided for the entirecontents of the largest tank plussufficient freeboard to allow for precipitation. Diked areas should be sufficiently imperviousto contain spilled oil.
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State
No Liner Required: CA, IL, MA No Breakthrough Within72 Hours: VA
1x10-4 cm/sec: MD 1x10-6 cm/sec: PA Reasonably Impervious(6 at 1x10-7 cm/sec): MN
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State
1x10-7 cm/sec: ID Sufficiently Impermeable:AK and LA
Impervious: KS and WI Liquid Tight: AL and 32 Other States
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Goals
Protect Environment Using Effective Methods
Retrofitting Options
LINER OPTIONS
Surficial Liners
Geomembrane
Geosynthetic Clay Liner
Compacted Clay
Concrete
Asphalt
Spray-On Liners
Enhanced ExistingSoil Liner
Biological Clogging
Chemical Clogging
Soil Cement
Chemical Grouting
Soil Bentonite
ENVIRONMENTAL/CONTROL OPTIONS
Environmental Controls
Slurry Walls
GW Control
Prevention and Enhancement
Double Bottoms in Tanks
Leak Detection Systems
Preventative Measures
Backflow Prevention
Overfill Prevention
Operational and Procedural Controls
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Retrofitting Options
Site Conditions
Existing
Conditions
Geometry
Penetrations
Regulatory
Acceptance
Engineering
Design Product
Compatibility Desiccation Resistance
Freeze-Thaw Resistance
Temperature
Extremes
Wind Resistance
Ultraviolet Resistance
Fire Resistance
Construction
Constructability
Availability of
Materials
Weather
Operator Issues
Operation &Maintenance OperationalFlexibility
Storm Water Management
Clean-up
Subsurface Remediation
Trafficability
Vegetation
Control
Cost
Capital
Maintenance
Clean-up
Remediation
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Retrofitting Options
GRADE
A
B
C
D
F
DEFINITION
Satisfactory Performance With Minimal Extra Effort
Satisfactory Performance if Specific Design Elements are Implemented
Significant Extra Effort May Be Required To Achieve Satisfactory Performance
Satisfactory Performance May Not Be Feasible
Satisfactory Performance Will Not Be Feasible
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Example
Tank Farm: 7 Tanks Total Area: 140,000 ft2 Open Area: 83,000 ft2 Area of Bottom: 57,000 ft2 Height of Dikes: 5 ft
Largest Tank: Diameter: 120 ft HProduct = 46 ft V = 93,000 bbls
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Example
Soil: Homogeneous Sand Deposit k = 10-5 m/sec Porosity: 0.35 Thickness: 100 ft Groundwater Depth: 5 ft
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1. Geomembrane 2. Geosynthetic Clay Liner 3. Spray-On Liners 4. Compacted Clay 5. Concrete 6. Asphalt
Evaluation of Options
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Option 1Geomembrane
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Option 2Geosynthetic Clay Liner
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Alternative Option
Install Double Bottoms and Overfill Protection in Tanks and Do Not Install Liner in the
Diked Area
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Comparison
Analyze two Scenarios: 1. Liner and Single Bottom 2. No Liner, Double Bottom,
Overfill Protection, andProduct Removal System
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Tank
Dike Dike HD
Reaction Time
Pump
Scenario 2
Comparison
Compare Volumes of Product Released to the Environment: Leaks Catastrophic Failure
V1= Volume Under Scenario 1 V2= Volume Under Scenario 2
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Performance Ratio
PR =
PR > 1 Scenario 2 PR < 1 Scenario 1
V1 V2
Scenario 1
Assume Bottom Leak: Pinhole d = 0.04 in. (1 mm) 1 Pinhole / Acre of Bottom 57,000 ft2 of Bottoms 1.32 Acres
V1 = (Bottom Leakage Rate)(Area of Bottom)(Time)
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0
25
50
75
100
125
150
175
200
225
250
0 10 20 30 40 50 Liquid Height in Feet
Flow
in g
pd/a
cre
Pinhole Leakage Rate
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From Graph Rate = 167 gpd/acre
V1 = (167)(57000/43560)(365)(42)
= 1,899 bbls/yr
Scenario 1
Scenario 2
Assume Catastrophic Failure of Tank
Assume Leak in Double Bottom
V2 = (leakage rate)(area ofbottom) (time) + (volumeinfiltrated in soil followingcatastrophic failure)
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Infiltration Following
Catastrophic Failure
Using XSLIM 93,000 bbls 2,500 gpm Pump Pumping Start in 6 hrs Depth of Penetration: 0.54 ft Volume of Product in Soil: (0.54)(83,000)(5.6)(0.35)=
2801 bbls
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http:0.54)(83,000)(5.6)(0.35
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Ponding Product
WettingFront
WettingFront
Moisture Content Profile
Depth Z
o s
Actual
Green-AmptModel
Soil Profile
Soil Surface
XSLIM - Infiltration Model
Soil Type M
axim
um In
filtra
tion
Dep
th (f
t) 35
30
25
20
15
10
5
0
Loam
Sand
Clay
0.1 1 10 100 1000 Time (hour)
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Using XSLIM Depth of Penetration:0.54 ft Volume of Product in Soil:
(0.54)(83,000)(5.6)(0.35) 2801 bbls
Infiltration FollowingCatastrophic Failure
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From Graph Rate =2.88 gpd/acre
V2 = 2801+ (2.88)(57000/ 43560)(365)/(42)
=2,801 + 32.8 bbls/yr
Scenario 2
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Performance Ratio
PR =
PR > 1 Scenario 2 PR < 1 Scenario 1
1,899 bbls/yr
2,801 + 32.8 bbls/yr
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0
1
2
3
4
5
6
7
8
1 2 3 4 5 6 7 8 9 10
Years
Perf
orm
ance
Rat
io
Defect Size=0.5mm Defect Size=1mm
PR=1
Performance Ratio
Performance
Unless There Is a Catastrophic Failure Every 6Years, the 0.5 mm Bottom
Leaks Are a Greater Risk to the Environment Than the
Catastrophic Failure
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Conclusion
Select Optimum Alternative for Secondary ContainmentBased on: Environmental
Consequence
Multiple Criteria In Example, Work on Tank
Provide Better Protection
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