alternatives to secondary containment lining - us epa · pdf fileimpervious to contain spilled...

GeoSyntec Consultants

ALTERNATIVES TO SECONDARY CONTAINMENT LINING

Corresponding Author: Tarik Hadj-Hamou, Ph.D., P.E.(1)

Phil Myers, P.E.(2)

Thierry Sanglerat, P.E.(3)

ABSTRACT

Federal regulations for the performance of secondary containment system for Aboveground Storage Tanks (AST) at bulk storage facilities states in 40 CFR §112.7(e)(2)(ii), that, “all bulk storage tank installations should be constructed so that a secondary means of containment is provided for the entire contents of the largest tank plus sufficient freeboard to allow for precipitation. Diked areas should be sufficiently impervious to contain spilled oil.” State requirements for the performance of secondary containment range from no specific requirements to specified numerical values for design (e.g., hydraulic conductivity, time to control and clean). While it is often assumed that building or retrofitting a secondary containment requires installation of synthetic liners, engineering alternatives exist that may provide equivalent or better protection of the environment.

This paper presents a methodology for selecting the optimum engineering alternative to retrofit secondary containments at bulk storage facilities. In the context of this paper, optimum engineering alternative is defined as the cost-effective engineering alternative that provides the required level of protection of the environment and meets operational constraints. The methodology is based on statistical analyses of failure and releases, risk analysis, and performance analysis.

The methodology is applied to an existing tank farm located inland and above the groundwater table. It is shown that, for this tank farm, optimum protection of the environment can be achieved with the installation of double bottoms, proper overfill

(1) Associate, GeoSyntec Consultants, 2100 Main Street, Suite 150, Huntington Beach, CA 92648 (714) 969-0800 – [email protected]

(2) Senior Standard Engineer, Chevron Products Company, 6001 Bollinger Canyon Road, P.O. Box 6004, San Ramon, CA (925) 842-2288 – [email protected]

(3) Executive Vice President, GeoSyntec Consultants, 2100 Main Street, Suite 150, Huntington Beach, CA 92648 (714) 969-0800 – [email protected]

thh/ast/publications/fwspill/hadj-hamoupaper.doc 1 02 07 08/15:50


prevention, and a perimeter catchment system around the tanks rather than through the installation of synthetic liners.

INTRODUCTION

The United States (US) Environmental Protection Agency (EPA) estimated in 1996 that approximately 502,000 facilities have Aboveground Storage Tanks (AST) and store significant quantities of oil in bulk. A typical facility consists of one or more AST. At most of these facilities, the AST are within a secondary containment area.

Historically, secondary containment areas have been built to provide horizontal confinement of the hypothetical spill. The design was governed by fire codes rather than environmental concerns. Consequently, the quality of the secondary containment system varies greatly and range from dikes built out of locally available soil to concrete walls [Figure 1]. The secondary containment area must contain the volume of the largest tank plus reasonable precipitation.

However, in recent years, concern has been the downward migration of product spilled in the secondary containment areas to groundwater and the lack of liners in the secondary containment areas. The USEPA (USEPA, 1996) estimates that approximately 84 percent of the AST facilities do not have impervious liners in the secondary containments.

Considering that a review of discharge data reported by the USEPA (USEPA 1996) indicated that 30 percent of reported oil discharges are to secondary containment areas, there has been an increase in regulatory pressure for requiring the installation of impervious liners in secondary containment areas.

Releases from ASTs may be classified into four broad categories:

• Shell Releases; • Bottom Releases; • Overfill; and • Equipment/Appurtenances Leaks.



Shell releases may occur as a result of structural failure of the shell. A distinction is made between rapid shell release due to total rupture of the shell and slow shell release due to a small defect or a minor failure (cracked fitting). Rapid shell releases due to catastrophic failure of the shell are rare. One of the best known cases is the rupture of the newly repaired diesel tank at the Ashland Oil Terminal in Floreffe Allegheny County, Pennsylvania. On 2 January 1988, the tank ruptured sending releasing almost 3.9 million gallons of diesel fuel [http://www.dep.state.pa.us/dep/pa_env-her/ashland.htm, 2002].

Bottom releases occur through pinhole at the bottom of the tank and are mostly related to corrosion of the bottom plates. Cutter (1999) reports that a leak at a rate of 1 drop/sec will result in a total volume of 34 gallons (128.7 l) or roughly 0.8 barrels in one month.

Overfill occurs when the volume of the product received exceeds the capacity of the tank. The oil is typically released through the roof vent. Overfill are most often related to operator errors.

Equipment/appurtenance releases typically involve a defect or a failure such as cracking or a gasket failure.

The American Petroleum Institute (API) conducted an extensive review of the different types of releases and proposed a series of detection and prevention measures (API, 1997). Because of the risk of environmental impacts from releases at ASTs, regulatory changes have occurred pushing for retrofitting secondary containments.

REGULATORY OVERVIEW

The Oil Pollution Act (OPA) was passed in 1990 and amends §311 of the Clean Water Act (CWA) to increase federal response authority and private response capability and liability. CWA §311 requires the preparation of plan to respond to worst-case discharge of oil and set forth the requirements for these plans. These requirements are detailed in a proposed revision to the Oil Pollution Prevention regulation published as Part 112 of Title 40 of the Code of Federal Regulations (40 CFR 112). In particular, §112.7 details the requirements for a Spill Prevention Control and Countermeasure Plans (SPCC



plan). Paragraph §112.7(e)(2)(ii) addresses the issue of secondary containment areas at bulk storage facilities and repairs that “Diked areas shall be sufficiently impervious to contain spilled oil.” The terminology sufficiently impervious is not defined in the regulations.

Other agencies that provide insight in the design of secondary containments are the National Fire Protection Association NFPA Code 30 (NFPA, 1993 and the EPA Liner Study, USEPA (1996). The fire code provides recommendation for height and spacing of the berms. The fire code further specifies that the dikes or berms should be liquid tight. The EPA Liner study does not make any recommendation for permeability of the liners and further specifies that the requirement should be part of a voluntary program at state level.

At the state level, a review of all state regulations indicated a wide range of requirements. Example of requirements include:

• No Liner Required: CA, IL, MA • Sufficiently Impermeable: AK and LA • Impervious: KS and WI • Liquid Tight: AL and 32 Other States that follow the NFPA 30 Fire

Code • No Breakthrough Within 72 Hours: VA • Specific Values of Hydraulic Conductivity: MD: 1 × 10-4 cm/sec, PA:

1 × 10-6 cm/sec, ID: 1 × 10-7 cm/sec

RETROFITTING OPTIONS

There are two major groups of options for retrofitting an AST facility to minimize the risk of contamination of the environment by releases. The first group includes the installation of liners in the secondary containment areas or enhancing the soil in place. The second group includes the installation of environmental controls or the use of preventative measures or enhancement of the tanks. Table 1 below lists different options for each of the two groups.



TABLE 1: RETROFITTING OPTIONS

LINER OPTIONS ENVIRONMENTAL/CONTROL OPTIONS Surficial Liners

Enhanced Existing Soil Liner

Environmental Controls

Prevention and Enhancement

Geomembrane Biological Clogging Slurry Walls Double Bottoms in Tanks Geosynthetic Clay Liner

Chemical Clogging GW Control Leak Detection Systems

Compacted Clay Soil Cement Preventative Measures Concrete Chemical Grouting Backflow Prevention Asphalt Soil Bentonite Overfill Prevention Spray-On Liners Operational and Procedural Controls

SELECTION METHODOLOGY

The selection methodology is a two-step process. The first step is to select the optimum liner. The second step is to select between a liner option and an environmental or enhancement option. To select, design, and implement the cost effective, technically sound and environmentally effective liner solution, a list of selection criteria was developed. The list includes criteria related to site conditions, engineering design, construction, operator issues, and cost. These criteria are listed in Table 2.

TABLE 2: SELECTION CRITERIA FOR LINER OPTIONS

Site Conditions Engineering Design Construction or Issues Cost

Existing Conditions Product Compatibility Constructability Operation &

Maintenance Capital

Geometry Desiccation Resistance

Availability of Materials

Operational Flexibility Maintenance

Penetrations Freeze-Thaw Resistance Weather Storm Water

Management Clean-up

Regulatory Acceptance

Temperature Extremes Clean-up Remediation

Wind Resistance Subsurface Remediation

Ultraviolet Resistance Trafficability

Fire Resistance Vegetation Control

Operat



The methodology for selecting the optimum liner option is based on a ranking of the options. Each option is graded with respect to each of the selection criterion using a qualitative grade scale. The qualitative grade scale developed to rank the liner options is shown in Table 3.

TABLE 3: GRADING SCALE

GRADE A Satisfactory Performance With Minimal Extra Effort B Satisfactory Performance if Specific Design Elements are Implemented C Significant Extra Effort May Be Required To Achieve Satisfactory Performance D Satisfactory Performance May Not Be Feasible F Satisfactory Performance Will Not Be Feasible

DEFINITION

A matrix is developed summarizing site information, comments about the applicability of each criterion to each liner option, and the qualitative grade assigned to each liner option. The matrix developed for the example examined in this paper is shown in Table 4. The grades are tallied up and a ranking of the options is then established based on the total grade of each option. The top three options are then examined further to ensure that they will meet the intent of the design and meet the Owner’s preferences if any.

The second step in the methodology is to compare the top-ranked liner option to a solution from the Environmental/Control group of options. This comparison is based on a risk analysis of the consequences of a spill. The risk analysis is based on an estimate of the volume of product that would be released on an annual basis to the environment under different scenarios and assuming a catastrophic failure.

To compare a liner in the secondary containment areas to a retrofitting of the tanks, the following two scenarios are examined:

• Scenario 1: Liner in the facility and single bottoms in the tanks. • Scenario 2: No liner in the facility and double bottom in the tanks.

Under scenario 1, the volume of petroleum product, V1 that will be released to the environment when a liner is installed in the open area and the single bottoms are left unchanged is given as:



V1 = (Leakage Rate through Bottom) x (Area of Bottom) x (Time)

Note that it is assumed in these scenarios the bottoms have defects and/or pinholes and that the liner installed in the secondary containment does not. This latter assumption is conservative as depths in liners installed in tank farms have been observed. Defects in liners come from puncture, incomplete seams, or gaps at boots installed around pipe penetrations (Figure 2). Studies by Giroud and Bonaparte (1989) have shown that geomembrane liners installed with strict construction quality assurance could be considered to have one to two defects per acre with a diameter of 2 mm. Using electric detection surveys Laine (1991) has shown that liners installed with strict construction quality assurance could have five or more defects per acre with diameter less than 0.5 mm. In tank farms where numerous boots are installed around pipe penetrations, support, and others appurtenances it is expected that even with a very strict construction quality assurance the number of defects will exceeds the numbers listed previously. The importance of these defects is very important as they lower the effectiveness of the liner to function as an impervious barrier. The role of such defect in lowering the effectiveness of liner was further demonstrated by King et al. (1997). King et al. (1997) showed that a geomembrane with a defect rate of about 2 in2/acre provided the same level of protection in the case of a catastrophic spill as a soil with a hydraulic conductivity of 10-5 cm/s.

Under scenario 2, the volume of petroleum product, V2 that will be released to the environment when double bottoms are installed in each AST and the open area within the secondary containment area is left unchanged is given as:

V2 = (Leakage Rate through Double Bottom) x (Area of Double Bottom) x (Time) + (Volume of Product Infiltrated in Soil Following A Hypothetical Catastrophic Failure)

The better scenario is the scenario that will minimize the volume of petroleum product release to the environment over the economic life of the tank farm.

Define a performance ratio to compare the two options:

PR=V1 / V2



Because PR is a function of time and of the volume of product infiltrated in the soil, it will depend upon the site characteristics such as the hydraulic conductivity of the soil, and will range from values less than one to values greater than 1. PR equals to 1 indicates that the two options are comparable. A PR greater than 1 indicates that the release to the environment is greater under Scenario 1 and, therefore, that Scenario 2 is a better scenario and installing double bottoms at the facility is a better option for protection of the environment than installing a liner in the facility while leaving the tank bottom untouched. The use of PR allows the owner to measure the level of risk he is willing to assume when considering retrofitting options.

EXAMPLE

The methodology discussed above is applied to a tank farm located inland in the Pacific Northwest. The tank farm includes 7 tanks storing refined petroleum product. The following information is available about the terminal:

TABLE 5: INFORMATION ABOUT SITE

Secondary Containment Areas: Total Area: 140,000ft2

Open Area: 83,000ft2

Area of Tank Bottom: 57,000ft2

Height of Dikes: 5ft

Largest Tank: Diameter: 120 ft Safe Fill Height: 46ft Volume: ≅ 93,000 bbls

Soil: Homogenous Sand Deposit k = 10-5 m/sec Thickness > 100ft Groundwater Depth: 50ft

Tank Bottoms: Average pinhole diameter d = 1 mm (0.04 in.) Average number of pinholes: 1/acre of bottom

Table 4 shows the ranking of the liner options for the facility. The ranking shows that a geomembrane is the preferred liner option. The second step is to compare installation of a geomembrane at the facility versus retrofitting the tanks by installing double bottoms with leak detection systems, a system of overfill protection at the terminal, and a spill recovery system. The spill recovery system consists of a pump with a pumping capacity of 2,500 gpm that can be activated in no less than 6 hours after a catastrophic spill has occurred.



The performance ratio PR discussed above is evaluated in the following. The volume of petroleum product, V1 that will be released to the environment on an annual basis when geomembranes are installed in the open area and the single bottoms are left unchanged is given as:

V1 = (Leakage Rate through Single Bottom) x (Area of Single Bottom) x (Time)

Using the Giroud et al. method (Giroud et al., 1997), the leakage rate is evaluated as a function of product height. Figure 3 shows flow in gallon/day as function of product height ranging from 0 to 50 ft. Under the product fill height of 46 ft in the tank, the leakage rate is 167 gallons per day (gpd) per acre.

V1= (167 gpd/acre)*(57,000ft2/43.560 ft2/acre*(365 days/year)/(42 gallons/bbl) V1= 1899 bbls/year

The volume of petroleum product, V2 that will be released to the environment on an annual basis when double bottoms are installed in each AST and the open area within the secondary containment area is left unchanged is given as:

V2 = (Leakage Rate through Double Bottom) x (Area of Double Bottom) x (Time) + (Volume of Product Infiltrated in Soil) following the catastrophic spill.

For a double bottom tank, we assume that there is about 0.5 in of product that may have gone undetected by the leak detection system on top of the original old bottom. Therefore we assumed that there is 0.5 in. of head driving the flow out of the double bottom system. Under this assumption the flow is about 2.88 gpd/acre (Figure 2).



The volume of product infiltrated in the ground is estimated using the numerical model XSLIM (eXpanded Soil Liner Infiltration Model) (Myers et al, 2001) developed to assess the effectiveness of soil liners in controlling hypothetical catastrophic spills in secondary containment areas. XSLIM simulates penetration of petroleum product into the soil liner and the underlying vadose zone. In addition, XSLIM takes into account the response time from the operators, the pumping rate, and the decreasing ponding height of petroleum product as it is recovered from the secondary containment area. The calculated depth of infiltration of product in the ground is 0.54ft. Consequently the volume of product infiltrated in the ground is equal to the depth times the area times the porosity of the soil:

V2 = (2.88) * (57000/43560)*(365 days/year)/(42 gallons/bbl)+ (0.54ft)*(83,000ft2)/(5.6ft3/bbl)*(0.35) V2=2801bbls + 32.8 bbls/year

To compare the two retrofitting option the performance ratio defined as:

PR= V1 / V2

is evaluated as a function of time and plotted in Figure 4. Figure 4 shows that the performance ratio is one at 1.5 years. This indicates that unless the return period of a catastrophic failure of the largest tank containing 93,000 bbls is less than 1.5 years then installing double bottoms in the seven tanks at the tank farms provide better protection of the environment. The performance ratio was calculated assuming a defect size of 0.5mm and is reported in Figure 4. Figure 4 indicates that the PR is equals 1 after 6 years. Unless a catastrophic spill occurs every 6 years, a better protection of the environment is obtained retrofitting the tank bottoms rather than placing a liner at the facility and leaving the tank bottom untouched.



CONCLUSION

This paper presented a methodology to select the optimum engineering alternative at bulk storage facilities. The methodology provides tools to select the optimum liner option and tools to compare the liner option to alternative approach to secondary containment lining. The methodology was applied to an example and it was shown that for the site-specific conditions of the facility the optimum engineering alternative to protect the environment is to install double bottom in the tanks with an overfill protection system.

The opinions expressed in this paper are those of the authors and one should not assume endorsement by the US EPA.

REFERENCES

American Petroleum Institute (1997), “Liquid Release Prevention and Detection Measures for Aboveground Storage Tanks, Publication Number 340, October.

Cutter Information Corporation (1999), Oil Spill Response Reference Guide.

Giroud, J.P., and Bonaparte, R. (1989), “Leakage Through Liners Constructed with Geomembranes – Part II Composite Liners,” Geotextiles and Geomembranes, pages 79-111.

Giroud, J.P., King, T.D., Sanglerat, T.R., Hadj-Hamou, T. and Khire, M.V. (1997), “Evaluation of the Rate of Liquid Migration Through Defects of a Geomembrane Placed on a Semi-Permeable Soil”, Geosynthetics International, Vol. 4., Nos. 3-4, pp.349-372

King, T.D., Haffner, J., Sanglerat, T.R., Hadj-Hamou, T. and Williamson, T.A. (1997), “Aboveground Storage Tank (AST) Secondary Containment Enhancement”, American Petroleum Institute 62nd Spring Refining Meeting, Environmental Symposium, San Diego, 7-9 April.



Laine, D.L. (1991), “Analysis of Pinhole Seam Leaks Located in Geomembrane liners Using the Electrical Leak Location Method – Case Histories,” Proceedings of Geosynthetics 1991, Volume 1, pp. 239-253, Atlanta.

Myers, P., Luccioni, L., Palmer, B., Hadj-Hamou, T., and Sanglerat, T.R. (2001), “Sufficiently Impervious Secondary Containment for AST’s,” Proceedings of 21st Annual International Operating Conference and Trade Show, Independent Liquid Terminals Association, Houston, Texas, 11-14 June.

National Fire Protection Association (1993), Flammable and Combustible Liquids Code, NFPA 30.

United States Environmental Protection Agency (1996), EPA Liner Study, Report to Congress, Section 4113(a) of the Oil Pollution Act of 1990, OSWER 9380.0-24, EPA 540/R95/041, PB 95-963538, May.


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Li

kely

(eff

ectiv

e, b

ut

nove

l app

roac

h)

B

S

I

GC

Lco

vere

d w

ith a

RM

ater

ial i

s ty

reg

the

dike

d

Reg

the

inte

inte

Pene

Req

uire

s

Ver

y

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

C

Geo

Synt

ec C

onsu

ltant

s

TA

BL

E 4

: RA

NK

ING

OF

LIN

ER

OPT

ION

S FO

R S

ITE

EX

AM

PLE

(con

tinue

d)

Geo

mem

bran

e G

eosy

nthe

tic C

lay

Lin

er

Spra

y-O

n L

iner

s C

ompa

cted

Cla

y C

oncr

ete

Asp

halt

Eng

inee

ring

Des

ign

Prod

uct

Com

patib

ility

Ta

nks c

onta

in c

omm

on

petro

leum

hyd

roca

rbon

pr

oduc

ts

Lim

ited

redu

ctio

n in

st

reng

th p

rope

rties

af

ter e

xpos

ure

to

hydr

ocar

bons

for

mos

t geo

mem

bran

e ty

pes.

stre

ngth

est

imat

es

can

be u

sed

for

desi

gn (I

.e. p

unct

ure

resi

stan

ce, w

eld

stre

ngth

, etc

.).

B

Not

sign

ifica

ntly

im

pact

ed b

y ex

posu

re to

hy

droc

arbo

ns if

hy

drat

ed

B

Not

of c

once

rn w

ith

poly

urea

; of m

inor

co

ncer

n w

ith

poly

uret

hane

B

If so

il is

dry

whe

n ex

pose

d to

hy

droc

arbo

ns,

perm

eabi

lity

will

be

high

; soi

l sho

uld

rem

ain

hydr

ated

C

Not

of c

once

rn

A

prod

uct

will

par

tially

de

terio

rate

the

asph

alt

D

Des

sica

tion

Res

ista

nce

Ave

rage

ann

ual

prec

ipita

tion

is 1

7 in

.; dr

iest

mon

ths a

re Ju

ly,

Aug

ust a

nd S

epte

mbe

r (a

vera

ge m

onth

ly

prec

ipita

tion

is le

ss

than

1 in

ch)

Not

of c

once

rn

A

Des

sica

tion

will

in

crea

se p

erm

eabi

lity

to a

n un

acce

ptab

le

leve

l; G

CL

mus

t re

mai

n hy

drat

ed;

irrig

atio

n m

ay b

e re

quire

d in

sum

mer

m

onth

s

C

Not

of c

once

rn

A

dess

icat

ion

will

in

crea

se p

erm

eabi

lty

in h

ighe

r-pl

astic

ity

mat

eria

ls; i

rrig

atio

n m

ay b

e re

quire

d in

su

mm

er m

onth

s

C

Not

of c

once

rn

A

Vol

atile

frac

tion

in

asph

alt w

ill

evap

orat

e w

ith ti

me;

m

ay in

duce

som

e cr

acki

ng

C

Free

ze T

haw

R

esis

tanc

e Fi

ve m

onth

s out

of t

he

year

(Nov

embe

r-M

arch

) hav

e av

erag

e hi

gh a

nd lo

w

tem

pera

ture

s tha

t are

ab

ove

and

belo

w

free

zing

Not

of c

once

rn

A

GC

L re

cove

rs fr

om

free

ze-th

aw c

ycle

s B

N

ot o

f con

cern

A

M

ay in

duce

m

icro

crac

king

and

re

duce

surf

icia

l pe

rmea

bilit

y

C

reez

e-th

aw m

ay

wor

sen

exis

ting

crac

king

C

Free

ze-th

aw m

ay

wor

sen

exis

ting

crac

king

C

Tem

pera

ture

Ex

trem

es

Diff

eren

ce b

etw

een

aver

age

annu

al h

igh

and

low

tem

pera

ture

is

61 d

egre

es; d

iffer

ence

be

twee

n al

l-tim

e hi

gh

and

all-t

ime

low

is 1

33

degr

ees

Tem

pura

ture

va

riatio

ns m

ay

indu

ce st

ress

co

ncen

tratio

ns a

nd

geom

embr

ane

rupt

ure

at w

elds

and

th

e ge

omem

bran

e m

ay b

ecom

e br

ittle

at

low

tem

pera

ture

s, bu

t the

cov

er so

il w

ill re

duce

the

effe

ct

B

Not

of c

once

rn

A

Som

e po

lyur

etha

nes

may

bec

ome

britt

le a

t lo

w te

mpe

ratu

res

B

Not

of c

once

rn

A

Tem

pera

ture

ex

trem

es m

ay in

duce

cr

acki

ng

C

Tem

pera

ture

ex

trem

es m

ay in

duce

cr

acki

ng

C

Win

d R

esis

tanc

e W

indi

est m

onth

s are

M

arch

and

Apr

il (a

vera

ge w

ind

spee

d =

13 m

ph)

Not

of c

once

rn

A

Not

of c

once

rn

Req

uire

s anc

horin

g at

dik

es; b

alla

st in

op

en a

reas

may

als

o be

requ

ired

B

Not

of c

once

rn

A

Not

of c

once

rn

A

Not

of c

oncr

en

A

Ultr

avio

let

Sunn

iest

mon

ths a

re

Not

of c

once

rn

A

Not

of c

once

rn

A

Lim

ited

Con

cern

B

N

ot o

f con

cern

A

N

ot o

f con

ern

A

Not

of c

oncr

en

Red

uced

Rel

ease

d

F

A

A

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

Geo

Synt

ec C

onsu

ltant

s

TA

BL

E 4

: RA

NK

ING

OF

LIN

ER

OPT

ION

S FO

R S

ITE

EX

AM

PLE

(con

tinue

d)

Geo

mem

bran

e G

eosy

nthe

tic C

lay

Lin

er

Spra

y-O

n L

iner

s C

ompa

cted

Cla

y C

oncr

ete

Asp

halt

Res

ista

nce

July

and

Aug

ust,

with

80

% a

vera

ge

poss

iblil

ity o

f sun

shin

e an

d 16

cle

ar d

ays p

er

mon

th

Fire

Res

ista

nce

Pote

ntia

l for

spill

and

su

bseq

uent

fire

is

cons

ider

ed lo

w;

smok

ing

is n

ot a

llow

ed

at e

ither

term

inal

Not

of c

once

rn

A

Not

of c

once

rn

A

Gen

eral

ly

flam

mab

le, b

ut

flam

e-re

tard

ant

poly

uret

hane

s are

av

aila

ble

B

Not

of c

once

rn

A

Not

of c

oner

n A

N

ot o

f con

cren

A

Ope

rato

r Is

sues

C

onst

ruct

ion

NO

ISSU

ES

Ope

ratio

ns a

nd

Mai

nten

ance

M

aint

enan

ce w

ill

incl

ude

perio

dic

insp

ectio

n an

d re

pair

of

liner

s at f

acili

ty

Rep

air r

equi

res

train

ed sp

ecia

lists

; di

ffic

ult t

o in

spec

t w

ith so

il co

ver

C

Easi

ly re

paire

d; b

ut

need

s to

rem

ain

cove

red

and

hydr

ated

C

requ

ires

train

ing

of p

erso

nnel

, bu

t rep

air k

its c

an b

e us

ed

B

Will

nee

d to

pre

vent

pl

ant g

row

th

B

Req

uire

s per

iodi

c in

spec

tion

and

seal

ing

of c

rack

s

B

Req

uire

s per

iodi

c in

spec

tion

and

seal

ing

of

crac

ks/p

atch

ing

B

Ope

ratio

nal

Flex

ibili

ty

Typi

cal o

pera

tions

in

clud

es p

aint

ing,

snow

re

mov

al, t

ank

insp

ectio

n an

d cl

eani

ng, a

nd ta

nk v

ac

truck

ope

ratio

n

Veh

icul

ar a

cces

s re

stric

tion

is re

duce

d by

the

cove

r soi

l, bu

t th

ere

will

still

be

size

lim

its fo

r veh

icle

s

B

cula

r acc

ess

rest

rictio

n is

less

ened

by

bur

ying

the

GC

L,

alth

ough

ther

e w

ill

still

be

size

lim

its fo

r ve

hicl

es

B

Acc

ess t

o ta

nks w

ill

be re

stric

ted

unle

ss

the

liner

is p

rote

cted

w

ith a

laye

r of c

over

so

il

B

Will

rest

rict

vehi

cula

r acc

ess i

f w

et u

nles

s cov

ered

w

ith g

ranu

lar

prot

ectiv

e la

yer

B

Not

of c

once

rn

A

Not

of c

once

rn

A

Stor

mw

ater

M

anag

emen

t A

vera

ge p

reci

pita

tion

is 1

7 in

./yr;

wet

test

m

onth

is D

ecem

ber

(2.3

in/m

onth

); w

ette

st

mon

th o

n re

cord

was

5.

7 in

.; sh

een

on w

ater

w

ill re

quire

trea

tmen

t

Goo

d flo

w a

long

ge

omem

bran

e su

rfac

e; n

eed

to

min

imiz

e po

ndin

g ne

ar ta

nk; s

heen

on

wat

er m

ay re

sult

from

impa

cted

soil

B

Flow

is sl

ower

than

ge

omem

bran

e; n

eed

to m

inim

ize

pond

ing

near

tank

; she

en o

n w

ater

may

resu

lt fr

om im

pact

ed so

il

C

Exce

llent

flow

; nee

d to

min

imiz

e po

ndin

g ne

ar ta

nk

A

Flow

is sl

ower

than

ge

osyn

thet

ic o

ptio

ns;

Shee

n on

wat

er m

ay

resu

lt fr

om im

pact

ed

cove

r soi

l

C

Exce

llent

flow

; nee

d to

min

imiz

e po

ndin

g ne

ar ta

nk

A

Exce

llent

flow

; nee

d to

min

imiz

e po

ndin

g ne

ar ta

nk; s

heen

may

re

sult

from

asp

halt

C

Cle

an-U

p Sp

ills m

ay o

ccur

due

to

over

fills

; unz

ippi

ng

spill

is c

onsi

dere

d hi

ghly

unl

ikel

y

Geo

mem

bran

e m

ay

be d

amag

ed d

urin

g cl

eanu

p op

erat

ions

; co

ver s

oil w

ill n

eed

to b

e re

mov

ed

C

Impa

cted

GC

L ca

n be

rem

oved

and

re

plac

ed w

ith n

ew

GC

L af

ter a

spill

; co

ver s

oil w

ill n

eed

to b

e re

mov

ed;

subs

eque

nt re

pair

is

easi

er th

an b

urie

d ge

omem

bran

e co

ver

B

May

be

dam

aged

du

ring

clea

nup

B

Req

uire

s soi

l re

mov

al

C

Not

of c

once

rn

A

Acc

iden

tal r

elea

se o

f pr

oduc

t (e.

g. o

verf

ill)

will

par

tially

de

terio

rate

the

asph

alt

C

Subs

urfa

ce

Rem

edia

tion

BTE

X, M

tBE,

and

ot

hers

wer

e no

t de

tect

ed a

bove

th

resh

old

clea

nup

leve

ls a

t eith

er si

te in

Req

uire

s sig

nific

ant

effo

rt to

rem

ove

for

acce

ss to

und

erly

ing

soil

and

repa

ir af

terw

ards

C

quire

s sig

nific

ant

effo

rt to

rem

ove

for

acce

ss to

und

erly

ing

soil;

subs

eque

nt

repa

ir is

eas

ier t

han

B

Easy

to re

mov

e fo

r ac

cess

to u

nder

lyin

g so

il

B

Und

erly

ing

soil

is

acce

ssib

le w

ith

min

or e

xcav

atio

n

B

Sign

ifica

nt e

ffor

t re

quire

d to

rem

ove

the

conc

rete

for

acce

ss to

und

erly

ing

soil

C

nific

ant e

ffor

t re

quire

d to

repa

ir af

ter r

emov

al

C

Rep

air

Veh

i

Re

Sig

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

Geo

Synt

ec C

onsu

ltant

s

TA

BL

E 4

: RA

NK

ING

OF

LIN

ER

OPT

ION

S FO

R S

ITE

EX

AM

PLE

(con

tinue

d)

Geo

mem

bran

e G

eosy

nthe

tic C

lay

Lin

er

Spra

y-O

n L

iner

s C

ompa

cted

Cla

y C

oncr

ete

Asp

halt

rece

nt m

onito

ring

repo

rts; r

emed

iatio

n is

no

t con

side

red

nece

ssar

y at

this

tim

e

burie

d ge

omem

bran

e co

ver

Traf

ficab

ility

V

ehic

les r

equi

re a

cces

s to

and

aro

und

the

perim

eter

of t

he ta

nks

Traf

ficab

le if

cu

shio

ned

and

cove

red

B

cabl

e if

cush

ione

d an

d co

vere

d

B

Will

rest

rict

vehi

cula

r acc

ess t

o ta

nks;

traf

ficab

le if

cu

shio

ned

and

cove

red

C

Traf

ficab

le u

nder

dry

co

nditi

ons

B

Not

of c

once

rn

A

Not

of c

once

rn

A

Veg

etat

ion

Con

trol

Con

tain

men

t are

as a

re

perio

dica

lly sp

raye

d fo

r w

eeds

, alth

ough

som

e w

eeds

wer

e fo

und

durin

g th

e si

te

insp

ectio

n

Veg

etat

ion

cont

rol

will

redu

ce th

e po

tent

ial f

or ro

ot

pene

tratio

n

B

Esse

ntia

l C

N

ot o

f con

cern

A

Es

sent

ial f

or p

rope

r pe

rfor

man

ce

C

Not

of c

once

rn if

cr

acks

are

seal

ed

B

Not

of c

once

rn if

cr

acks

are

seal

ed

B

Cos

ts

Eco

nom

ic a

nd P

oliti

cal C

rite

ria

Cap

ital c

ost p

er

squa

re fo

ot (n

ot

incl

udin

g en

gine

erin

g an

d C

QA

)

Prel

imin

ary

cost

s to

be

used

for c

ompa

rison

pu

rpos

es o

nly

and

not

for b

id p

repa

ratio

n;

thes

e co

sts w

ill n

eed

to

be re

fined

prio

r to

bid

prep

arat

ion

Mod

erat

e to

hig

h --

$2.8

0 - 4

.30

(incl

udes

geo

text

ile

cush

ion,

boo

ts,

seal

ing

arou

nd ta

nk,

and

1 ft

prot

ectiv

e co

ver s

oil)

C

Mod

erat

e --

$2.

60 -

3.40

(inc

lude

s ge

otex

tile

cush

ion

and

1-ft

prot

ectiv

e co

ver s

oil)

C

Hig

h --

$4.

00 -

7.00

(r

ange

for f

lexi

ble

and

rigid

type

po

lyur

etha

nes)

D

Low

to m

oder

ate

--$1

.70

- 4.0

0 (f

or 2

-ft

thic

k la

yer;

incr

ease

co

st fo

r hau

ling

dist

ance

s gre

ater

than

20

mile

s; to

tal c

ost

incl

udes

gra

ding

of

exis

ting

surf

ace,

ha

ulin

g, sp

read

ing

and

com

pact

ion)

C

Hig

h --

$5.

00 -

6.60

(f

or 6

to 8

-in.

rein

forc

ed sl

ab)

D

Hig

h --

$4.

50 -

5.40

(in

clud

es

base

, and

4 in

. tot

al

asph

alt t

hick

ness

)

Mai

nten

ance

M

aint

enan

ce m

ay

incl

ude

deve

geta

tion,

pe

riod

insp

ectio

ns a

nd

repa

irs a

t eac

h te

rmin

al Lo

w (s

houl

d pr

even

t pl

ant g

row

th)

B

Mod

erat

e (G

CL

mus

t re

mai

n hy

drat

ed)

C

Low

(rep

air k

its a

re

avai

labl

e)

B

Low

(mus

t pre

vent

pl

ant g

row

th)

B

ow (p

erio

dic

insp

ectio

n an

d cr

ack

seal

ing)

B

Low

(per

iodi

c in

spec

tion

and

crac

k se

alin

g)

B

Cle

an-U

p Sp

ills m

ay o

ccur

due

to

over

fills

; unz

ippi

ng

spill

is c

onsi

dere

d hi

ghly

unl

ikel

y

Hig

h (r

emov

al o

f co

ver s

oil a

nd

poss

ible

repa

ir of

ge

omem

bran

e)

D

Hig

h (r

emov

al o

f co

ver s

oil a

nd

repl

acem

ent o

f GC

L)

D

Low

(som

e re

pair

may

be

requ

ired)

B

H

igh

(due

to so

il re

mov

al)

D

Low

B

H

igh

(rep

air o

f pa

ving

fabr

ic sy

stem

) D

Rem

edia

tion

BTE

X, M

tBE,

and

ot

hers

wer

e no

t de

tect

ed a

bove

th

resh

old

clea

nup

leve

ls a

t eith

er si

te in

re

cent

mon

itorin

g re

ports

Hig

h (d

ue to

rem

oval

of

soil

and

geom

embr

ane

and

repa

ir of

ge

omem

bran

e)

D

Mod

erat

e (d

ue to

re

mov

al o

f cov

er so

il an

d re

pair

of G

CL)

C

(rem

oval

an

d re

pair

of c

over

re

quire

d

C

Low

B

H

igh

(rem

oval

of

conc

rete

requ

ired)

D

H

igh

(rep

lace

men

t of

pavi

ng fa

bric

syst

em)

D

Ove

rall

Perf

orm

ance

Ex

celle

nt

A

Exce

llent

A

Ex

celle

nt

A

Exce

llent

A

Ex

celle

nt

A

Exce

llent

A

Traf

fi

6 in

. to

1 ft

L

Mod

erat

e

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

C

Geo

Synt

ec C

onsu

ltant

s

TA

BL

E 4

: RA

NK

ING

OF

LIN

ER

OPT

ION

S FO

R S

ITE

EX

AM

PLE

(con

tinue

d)

Geo

mem

bran

e G

eosy

nthe

tic C

lay

Lin

er

Spra

y-O

n L

iner

s C

ompa

cted

Cla

y C

oncr

ete

Asp

halt

Ove

rall

Rel

iabi

lity

Goo

d B

A

vera

ge

C

Goo

d B

A

vera

ge

C

Ave

rage

C

A

vera

ge

Cri

tical

Pe

rfor

man

ce

and

Rel

iabi

lity

Issu

es

Prop

er c

onst

ruct

ion

and

CQ

A a

re

impo

rtant

to a

chie

ve

acce

ptab

le

perf

orm

ance

; po

tent

ially

hig

h cl

eanu

p co

sts

GC

L m

ust b

e in

itial

ly c

onfin

ed a

nd

hydr

ated

rem

ain

conf

ined

and

hy

drat

ed to

per

form

pr

oper

ly; p

oten

tially

hi

gh c

lean

up c

osts

Susc

eptib

ility

to

dam

age

(alth

ough

no

t as s

usce

ptib

le a

s a

geom

embr

ane)

and

co

st

Susc

eptib

le to

de

ssic

atio

n cr

acki

ng;

pote

ntia

lly h

igh

clea

nup

cost

s; h

igh

soil

proc

urem

ent

cost

s may

pro

hibi

t th

is o

ptio

n

Hig

h co

nstru

ctio

n co

sts,

pote

ntia

l for

cr

acki

ng, a

nd

pote

ntia

lly h

igh

clea

nup

effo

rt

Spill

will

che

mic

ally

at

tack

the

asph

alt;

ther

e is

a si

gnifi

cant

po

tent

ial f

or c

rack

ing

and

a po

tent

ially

hig

h cl

eanu

p ef

fort

asso

ciat

ed w

ith th

is

optio

n C

OM

ME

NT

S Th

is is

an

effe

ctiv

e,

relia

ble

liner

that

can

be

con

stru

cted

at a

m

oder

ate

cost

and

im

pose

less

hi

ndra

nce

to

oper

atio

ns th

an th

e ex

pose

d ge

omem

bran

e

This

is a

n ef

fect

ive

liner

, but

it m

ust

rem

ain

conf

ined

and

hy

drat

ed to

per

form

pr

oper

ly

This

line

r is

able

, re

liabl

e, a

nd

exce

llent

for o

dd

geom

etrie

s, bu

t so

mew

hat e

xpen

sive

This

is a

n ef

fect

ive

liner

, but

may

de

ssic

ate

if no

t hy

drat

ed;

proc

urem

ent c

osts

co

uld

be h

igh

This

line

r is

expe

nsiv

e an

d su

scep

tible

to

crac

king

, but

ef

fect

ive

and

dura

ble

This

line

r is

effe

ctiv

e, b

ut

susc

eptib

le to

ch

emic

al a

ttack

du

ring

a sp

ill

RA

NK

1

2 3

5 6

7

dur

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

C

Geo

Synt

ec C

onsu

ltant

s

FIG

UR

E 1

: TY

PIC

AL

SE

CO

ND

AR

Y C

ON

TA

INM

EN

TS

02 0

7 08

/15:

50TH

H/A

ST/H

ADJ-

HAM

OU

PAPE

R.D

OC

Geo

Synt

ec C

onsu

ltant

s

FIG

UR

E 2

: DE

FEC

TS

IN G

EO

ME

MB

RA

NE

S

02 0

7 08

/15:

50TH

H/A

ST/H

ADJ-

HAM

OU

PAPE

R.D

OC

Geo

Synt

ec C

onsu

ltant

s

FIG

UR

E 3

: LE

AK

AG

E R

AT

E T

HR

OU

GH

DE

FEC

T IN

TA

NK

BO

TT

OM

0 25

50

75

100

125

150

175

200

225

250

0 10

0

30

0 0

Liqu

id H

eigh

t in

Feet

Flow in gpd/acre

24

5

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

Geo

Synt

ec C

onsu

ltant

s

FIG

UR

E 4

: PE

RFO

RM

AN

CE

RA

TIO

0 2 4 6 8 10

12

14

16 0

5 10

15

20

25

30

Ye

ars

Performance Ratio

Def

ect S

ize=

0.5m

m

Def

ect S

ize=

1mm

PR=1

THH

/AST

/HAD

J-H

AMO

UPA

PER.

DO

C

02 0

7 08

/15:

50

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