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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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