"Sr
- «^ jnnea States environmental Protect.cn Agency .nter.Ti Infective .Nur~o»
Washington DC 2C-160 ^, ..
V>EPA OSWER Directive Initiation Reauest -IHBi.ro -/*
Name o' Contact Person
William J. Kline
Lead G^c* [2 OUST
P 1 r
i_l QERR i I OWPE
KJ OSVV n A^.CSWE*
Ma,, Code e.eonone \umoer
WH-565A 382-3081
S.gratureot Office Director Oaie
\ ' ^ » 1 1 '-y C
<:jjXU>«. LOsAAJ-U-r^v / vc«L<-C^ U_viA-*-i--) 1 - ' ~f c (o
T.i ;
Guidance Manual for Hazardous Waste Tank Standards (Subpart J)
ummary o t 3' r 5 c 11 v e
Revisions to the hazardous waste tank standards were proposed in June 1985. Final
revised standards are expected to be published in June 1986. Because these revisions
essentially overhaul the existing Subpart J tank standards and incorporate major new
requirements, a guidance manual would be of considerable use to both permit writers
and permit applicants to understand what information is necessary to facilitate the
permitting process. Even prior to these revisions being made, there have been many
requests from the regions for such a document.
Our plan is to have this manual ready for distribution at time of promulgation (June
of the revised tank standards.
This document will not duplicate the information that is in existing guidance manuall
Where necessary, reference is made to appropriate existing manuals. This guidance
manual strictly focuses on Subpart J technical tank standards.
Regions, 1,5,7,8, and 10 have been involved in reviewing drafts of sections of this'
document.
T-/ce 01 Oi-ec:.ve tWanuai. fancy 3irecti*e Announcement, etc i
**
Manual
S3
New
Final
n
3ocs in,s Jirectiv* Super»«gv Ji'j'tf ci Leao O't'Ce Directives
- ot OSWER Directives O't.cer
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- 1.1 -
1.0 INTRODUCTION
1.1 Purpose
Owners ana operators of existing and new hazardous waste storage and
treatment tank systems are required to submit Part 8 of their permit
applications to illustrate compliance with the standards of 40 CFR 264,
Subpart J. If yoj are currently operating an existing facility under Interim
Status (40 CFR 265), you will nave submitted Part A of your application.
Owners and operators of new facilities must submit Parts A and B together.
Tne Part 25^, S-opa^t J st = n,oaros nave been aooptea under the Resource
Conservation ana Recovery *ct v*C,Kn; ar,c a^e usea by EP* to issue permits to
tank facilities that store ana treat hazardous waste. These standards
identify requirements that all hazardous waste storage and treatment tank
systems must meet. This manual presents guidance on methods that should be
used in preparing Part B permit applications that demonstrate compliance with
the tank requirements of 40 CFR 264, Subpart J, as revised on .
Permit applicants must note that the 270.16 specific information
-rerquirements for nazardous waste tanks are only a tank-specific supplement ID
the 270.14(b) general information requirements. Ultimately, the 270.14(b)
general information requirements must be submitted jointly with the
information specific to tanks (270.16) to complete Part B permit applications.
1.2 Provisions of the Manual
The information which the permit applicant must submit in the Part B
permit application to demonstrate compliance with the treatment, storage, and
disposal standards is stipulated in 40 CFR 270. This establishes the
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- 1.2 -
requirements of EPA's permit program for hazardous waste management
facilities. The general information requirements that must be addressed are
contained in Sec. 270.14(b) of 40 CFR 270. [See Permit Applicant's Guidance
Manual for the General Facility Standards of 40 CFR 264 for further detail on
these general requirements.] The specific Part B information requirements for
tank systems are containea in Sec. 270.16, as revised. These specific
requirements are the major focus of tnis guidance manual. Tne specific Part B
information requirements for tanK systems under Sec. 270.16 include:
(a) Structural integrity and suitability assessment Dy a
professional engineer;
(b) Description of dimensions and capabity of the tank(s);
(c) Feed systems, safety cutoff, bypass systems and pressure
controls description;
(d) Piling, inst'-unent at ion ana process flow diagrams;
(e) Corrosion protection system descriptions;
(f) Descriptions of installation procedures;
(g) Secondary containment system descriptions;
(h) Descriptions of partial secondary-containment systems anc
aoditional ground water information required for tan* systems
not in compliance witn the full secondary containrent
requirements;
(i; A description of alternate design and operating practices for
tank systems exempt from secondary containment requirements;
(j) Spill and overfill prevention system descriptions;
(k) Operating procedures and tank system description for tank
systems that store or treat ignitable, reactive or incompatible
wastes.
This manual provides guidance on means of complying with the above information
requirements. In addition, the manual provides guidance on inspection
procedures, unfit-for-use tank system corrective action procedures, and
closure/post-closure care procedures, as required under Part B General
Information Requirements 270.14(b)(5) (7) and (13). For each of these areas,
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- 1.3 -
the information in tnis manual presents the applicable regulatory citations,
guidance on achieving the information requirements and referenced standards,
examples of suitable application information, and major points to address in
preparing the permit application.
Although tne guidance noted aoove is tne main intent of tnis manual,
introductory and background information is also included to provide better
understanding of the regulations and the permitting process. If the permit
application is prepared in conformance with the specific guidance presented
here [in Sec. 270.16] and in comforance witn the entirety of the general
information requirements [ln Sec. 270.14(b)j, it will, at a minimum, expedite
agency review of the application, and snould markedly improve the likelihood
of a permit being granted.
1.3 organization of tne Manual
Introductory Sections 2.0 and 3.0 explain the background of RCRA Subtitle
C (the Hazardous Waste Management Subtitle of RCRA), the specific status of
Subtitle C rulemaking for tanks, and the RCRA permitting process employed by
EPA. Section 4.0 provides an overview of 40 CFR Parts 270 and 264. Finally,
sections 5.0 - 14.0 address the Part B information requirements identified in
Part 270, identify each corresponding standard in Part 264, and provide
guidance to the permit applicant or how to comply witn the requirements.
1.4 Other Guidance Manuals
Other guidance manuals exist or are in preparation and will be of use in
preparing the overall Part B permit application. For instance, the RCRA
Permit Writer's Manual for Ground Water Protection will be very helpful for
the permit applicant in understanding and complying with the ground water
monitoring requirements in the 40 CFR 270.16 standards. The Permit
Applicant's Guidance Manual for the General Facility Standards will be a
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I )
- 1.4 -
useful tool for complying with the general information requirements in a Part
B permit application. The permit applicant will be notified throughout this
test when other guidance manuals are particularly useful and in what sections
of those manuals the pertinent information can be found. Appendix A provides
a list of otner pertinent technical documents, locations where they can be
revievvea or purchased, ana synopsis of the document. It is recommended tnat
the permit applicant become familiar witn the available literature because, in
total, this DO ay of information will be of greater assistance in preparing a
permit application.
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» I
2-1
2.0 BACKGROUND
2.1 Status of Subtitle C
In 1976, tne Resource Conservation and Recovery Act (RCRA) was passed Dy
Congress to reflate tne handling ana disposal of hazardous waste. THIS act
mandated the development of regulations governing the actions of owners or
operators who generate, transport, treat, store, or dispose of solid wastes.
The complete text of RCRA ard us associatea amendments are too long for
inclusion in this document. Tne end of this section includes information on
where interested parties may obtain copies of the Act ana otner related laws
and regulations.
RCRA, as amenaea oy tne Quiet Communities Act of 1976, tne used Oil
Recycling Act of 1980, and the Solid Waste Dis/^sal Act Amendments of 1950,
is, itself, an amendment of Title II of the Solid Waste Disposal Act. RCRA
was again amended on November 8, 1984 when the Hazardous and Solid Waste
Amend- ments (HSWA) of 1984 were signed into law.
Under the amended HSWA, "Subtitle C -- Hazardous Waste Management"
incorporates several sections which serve as the basis for the development of
the hazardous waste regulations that are promulgated by EPA. Suotitle C
states what EPA must do to govern hazardous waste handling and disposal and
provides EPA with the authority to carry out the provisions of the Act.
2.2 Status of Subtitle C Rulemaking for Tanks
EPA promulgated Interim Status standards for hazardous waste storage and
treatment tanks in May 1980 under Part 265, Subpart J [45 FR 33244-33245].
These standards emphasized the usage of appropriate operating procedures to
prevent hazardous waste releases from tanks.
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t
2-2
In January of 1981, RCRA permitting standards were promulgated for
hazardous waste storage and treatment tanks that could be entered for inspec-
tion. (Underground tanks that are not enterable for inspection are precluded
from obtaining a RCRA permit.) The major emphasis of these standards was
ensuring the structural integrity of tanks to protect against tank leaks or
ruptures or collapses. Requiregents under these standards included:
1) adequate tan< design;
2) maintenance of minimum shell tmckness;
3) routine inspection schedules; and
4) specific requirements for ignitable, reactive and incompatible
wastes.
Upon promulgation of these permitting standards, EPA was also considering 1)
including a secondary containment requirement for all tar.KS ana 2; saining tne
usage of underground tan*<>s or tan^s located in tne water taole. PJDMC com-
ment on these future rulemaKing issues was requested at that time.
On DATE , Part 264 hazardous waste treatment and storage
tank permitting standards were revised. These most recent revisions serve
many purposes. As indicated in the June 1985 Preamble, tney fulfill the
regulatory approach for tanks described in tne January 1931 Preamble by 1)
providing permitting standards under Part 264 for underground tanks that can-
not be entered for inspection, 2} by stipulating corrosion protection require-
ments for metal tank systems, and 3) specifying tne selection of an appropri-
ate secondary containment approach. These revisions also comply with the
mandates of the 1984 amendments stipulating that new underground tanks be
equipped with leak detection system [RCRA Section 3004(o)(4)j and that EPA
issue permitting standards for underground tanks which cannot be entered for
inspection [RCRA section 3004(w)]. Also, additional revisions and require-
ments were warranted as certain existing standards had proven incomplete
and/or unworkable.
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2-3
TABLE 2-1
Resource Conservation & Recovery Act
(Novemoer 1984)
"Sec. 3001. Identification ana "isting of hazardous waste
"Sec. 3002. Stanaara applicable to generators of hazardous waste
"Sec. 3003. Standards applicaole to transporters of Hazardous waste
"Sec. 3004. Standards applicaole to owners and operators of hazardous waste
treatment, storage, ana disposal
"Sec. 3005. Permits for treatment, storage, or disposal of hazardous waste
"Sec. 3006. Authorized State nazaraous waste programs
"Sec. 3007. inspectors
"Sec. 3008. Feaerai enforcement
"Sec. 3009. Retention of State authority
"Sec. 3010. Effective date
"Sec. 3011. Authorization of assistance of States
"Sec. 3012. Hazardous waste site inventory
"Sec. 3013. Monitoring, analysis,, and testing
"Sec. 3014. Restrictions on recyclec oil
"Sec. 3015. Expansion during interim status
"Sec. 3016. Inventory of federal agency hazardous waste facilities
"Sec. 3017. Export of hazardous waste
"Sec. 3018. Domestic sewage
"Sec. 3019. Exposure information and health assessments
Source: Resource Conservative and Recovery Act, PL98-616, November 8, 1984.
BNA, Environment Reporter, 12/28/84, 71:3101.
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- 3.1 -
3.0 THE PERMITTING PROCESS
3.1 Introduction
Tnere are t/c pa^ts of Title 43 of tne Coae of Federal Regulations that
contain information on the RCRA permitting process. Part 270 contains info--
mation on what an applicant and EPA must do regarding a permit. This Part
contains basic permitting requirements for EPA-administered RCRA programs,
such as application requirements, standard permitting conditions, and mon-
itoring and reporting requirements. Part 124 establishes the decisionmaking
procedures for EPA issuance of RCRA permits. This Part also establishes the
procedures for administrative appeals of EPA permit decisions.
Appendix A cites useful sources of information that will assist tne pe"-
^it applies''', in p-e:i-~i" 3" a;:'! icat":- ana Serve*"1 4. 3. p'^vic-s a- O'.e-vie.,
of the requirements of 40 CFR Parts 254 ana 270. If the permit applicant is
not familiar with any of the noted topics, these sections are essential rea-
ding before proceeding to the guidance presented in Sections 5.0 - 14.0.
As noted, the permit applicant should use the guidance on procedures ana
methods in Sections 5.0 - 14.0 to prepare those parts of the Part E appli-
cation that support the specific information requirements of 270.16 and the
general information requirements in 270.14;o)(5), (7), and (13). Each of
these information requirements is addressed in a separate section. Be advised
that in addition to the information requirements addressed in this manual, the
permit applicant must also comply with the entirety of the 270.14(b) Part B
General Information requirements.
Appendices are included at the end of the manual to provide supplementary
information such as names and addresses of state and federal regulatory
agencies, and locations where the permit applicant can request pertinent docu-
mentation, reports and maps. Other information of a more technical nature is
also included (see Appendix A). (For further information on the overall steps
in the permitting process, logistic nn n«^ application submissions, con-
fidentiality and appeal procedure information, see Permit Applicant's Guidance
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- 3.2 -
TABLE 3-1
EPA Regional Hazardous Waste Program Offices
Region I: OFFICE OF THE DIRECTOR
State Waste Programs Branch
Waste Management Division
John F. Kennedy Federal Building
Boston, MA 02203
(617) 223-6833
Region II: OFFICE OF THE DIRECTOR
Sol id Waste Brancn
Air ana Waste Management Division
26 Federal Plazd
New York, Nv 10278
( 9 ^ *~ 9 £ >^ r ~ ~ -
\C \ L , ^D^-^^oD
Region III: OFFICE OF TnE DIRECTOR "
Waste Management Branch/RCRA Permit Section
Air and Waste management Division
841 Chestnut Street
Philadelphia, PA 19107
(212) 597-0980
Region IV: OFFICE OF THE DIRECTOR
Residuals Management Branch/Waste Engineering Section
Air anc Waste Management Division
345 Cortland Street NE
Atlanta, GA 30365
(404) 831-3015
Region V: OFFICE OF THE DIRECTOR
Waste Management Branch
Waste Management Division
Federal Building
230 Dearborn
Chicago, IL 60604
(312) 886-7579
Region VI: OFFICE OF THE DIRECTOR
Hazardous Materials Branch *
Air and Waste management Division
First International Building
1201 Elm Street
Dallas. TX 75270
(214) 729-2645
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- 3.3 -
TABLE 3-1 (continued)
Region VII:
Region VIII
Region IX:
OFFICE OF THE DIRECTOR
Waste Management Branch
Air and Waste Management Division
726 Minnesota Avenue
Kansas City, Kf, 66101
(913) 236-288S
OFFICE OF THE DIRECTOR
Uaste Management Division
RCRA Management Branch
Suite 900, 1860 Lincoln Street
Denver, CO 70295
(303) 293-1662
OFFICE OF THE DIRECTOR
Programs Branch
Toxics and Waste Management Division
215 Fremont Street
San Francisco, CA 94105
Region X:
OFFICE OF THE DIRECTOR
RCRA Branch
Air and Waste Management Division
1200 6th Avenue
Seattle, WA 98101
(206) 442-2851
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This section of the manual presents a simplified description of the major
steps that must be taken by both an applicant and by EPA during the RCRA per-
mitting procedure. It also identifies those Parts of Title 40 that are of
importance to an owner or operate^ seeking a RCRA permit.
The overall RCRA permitting process can be summarized into the following
steps:
Step 1 The owner or operctor of a hazardous waste management facility
(in this case tank systems that store or treat hazardous waste)
completes Part A and B of a RCRA permit application and submits
the application to the appropriate EPA office.
Step 2 EPA reviews the application for completeness. If incomplete,
EPA sends a list of deficiencies, in writing, to the appli-
cant. If complete, tne applicant is so informed in writing.
Ster 3 V.'h-2" neces £ iv~.', tie arc'ics". ;:"£;: 2"~es aid submits the z-^^-
tional information requested.
Step 4 If not done in Step 2, the EPA reviews original and additional
submittals and notifies the applicant, in writing, of the com-
pleteness of the application.
Step 5 The EPA reviews the application and prepares a draft permit _p_r_
issues a notice o~ intent to deny the application. In eitheT
case, the EPA simultaneously prepares and issues a statement of
basis or a fact sheet.
Step 6 The E?A sends copies of the document prepared in Step 5 to the
applicant and others, and simultaneously makes a public notice
tnat a permit application has been prepared. The public notice
will provide 45 days for public (or applicant) comment.
Step 7 If, at the time of public notice, or at any time during the 45
day comment period, anyone, including EPA, requests a public
hearing, one will be scheduled and announced a minimum of 30
days before the scheduled hearing date.
Step 8 EPA prepares and issues a final permit decision.
These eight steps are a simplified description. The overall process is pre-
sented in more detail in Figure 3-1 and a full description of the steps that
EPA must take after receiving a complete RCRA permit application is contained
in Subpart A of Part 124 in Sec. 124.3 through 124.21.
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3.2 The Permit Application and the Permit
The RCRA permit application consists of two parts: Part A, a form re-
quiring completion, and Part B, which has no standard format. This manual is
desianed to assist applicants in preparing the information subnittal whic^ is
the Part B of an application for a RCRA permit.
Part 270 of Title 40 of the CFR provides the information requirements
necessary for a complete RCRA permit application (Parts A and B). All of the
sections of Subpart B of Part 270 should be read and understood by an owner or
operator who is applying for a RCRA permit for the first time.
The actual permit will consist of written approval of the contents of the
complete permit application. It will require the applicant to adhere to all
state^e^ts ^2:^ IP tne a.~>:1':atio~ an: /,:1"1 a^s? incljce conditions that must
be complied with in acsiticn to the application statements. Applicants in-
terested in the types of conditions that may be contained in a permit are
referred to Sec. 270.30 - "Conditions applicable to all permits" and Sec.
270.32 - "Establishing permit conditions."
3.3 Where to Submit Applications
Table 3-1 lists the mailing addresses and tie telephone numbers of the
EPA offices in each of the ten EPA Regions where permit applications should be
submitted. Personnel in these offices may be contacted with any questions
that may arise during preparation of a permit application.
Many states have their own hazardous waste permitting programs. These
programs may be in addition to or in lieu of the EPA RCRA program. State pro-
gram offices are listed in Appendix E. Any applicant who is unsure of which
agency an application should be submitted to should contact the Regional EPA
office (Table 3-1) for clarification.
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3.4 Confidentiality
An applicant may find it necessary, or may be required, to include con-
fidential information in an application. All applicants are referred to Sec.
270.12 - "Confidentiality of Information" in Subpart B of Part 270. Of par-
ticular note are tie ite.TS in Sec. 270.12(b) that c_a n n o t be claimed as
confidential.
To assert a claim, the provisions of 40 CFR require that the applicant
attach a cover- sheet to the information, or stamp or type a notice on each
page of the information, or otherwise identify the confidential portion(s) of
the application. Words such as "trade secret," "confidential business in-
formation," "Proprietary," or "company confidential" should be used. The
notice should also state whether the applicant desires confidential treatment
only until a certain date or a certain event.
Whenever possible, the applicant should separate the information con-
tained in the application into confidential and nonconfidential units and sub-
mit them under separate cover letters. Claiming confidentiality for a large
portion of the information in the permit application and failing to separate
the application into confidential and nonconfidential units may result in a
significant delay in processing the permit application because the EPA lac
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3. Mail (or otherwise ship) the material with return receipt (or equi-
valent) requested.
The EPA is not liable for release of information that an applicant has
submitted but failed to identify as c:--^:iii. Additional infarction on
EPA's handling of confidential information can be found in Part 2 of Title 40
of the CFR.
3.5 Appeals
It is possible to appeal the contents of a final RCRA permit. The pro-
cedure for petitioning EPA to review any condition of a permit decision is
contained in Sec. ',24. 19 - "Appeal of R3-,-, J,i1, anc FSO Permits." .In addi-
tio-., -^ c- -:-;- :-. -,:; c..- ir'f.if.r tc ' = - ' e .. ,.4
either case, a petition or decision to review a final permit "must be matie-
within 30 days after a RCRA final permit decision has been made under Sec.
124.15.
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4-1
4.0 OVERVIEW OF PASTS 270 i 264
An overview of Parts 270 and 264 is presented in this section because
this manual, as aforementioned, doe? not provide Guidance on all of the infor-
mation that rjst he developed, compiled and submitted in Part B of the permit
application. This overview identifies what reauirements are discussed here
and discusses how these relate to other reauirements of the peculations.
On April 1, 1983, EPA published in the Federal Register, Part 270 of
Title 40 of the Code of Federal Regulations. That new Part (see 48FR14146,
4/1/83) is titled "EPA Administered Permit Programs: The Hazardous Waste
Permit Program."
The vp- "> pfi c*" < ir n^-t ° ?"' ^re?"?1"*. the basic Fp£ oermittina
for a RCKA permit. ?ermt application reauirements, standard permit con-
ditions, and monitoring and reporting reauirements are all presented in Part
270. Subpart B of Part 270 is titled "Permit Application." The sections in
that Subpart identify all the items of information that must be submitted with
a permit application. This mania! focuses on the specific information re-
auirements for hazardous waste tanks that must be contained in Part B of a
permit application (Sec. 270.16). In addition, as noted in the introduction,
this manual provides guidance on inspection procedures, unfi t-f or-use tank
system correct ive action procedures a^"1 closure/Post closure procedures which
3re general information recuVe--erits contained in Sec. 270. 14(b) (^) , (7), and
(13).
In addition to the reauirements in Part 270, separate technical per-
mitting regulations are stipulated in Part 264. The Part 264 regulations
establish minimum Federal standards that define the acceptable management of
hazardous waste. The text of Part 270 refers the reader to the sections of
Part 264 which contain the standards that a permit applicant must demonstrate
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4-2
compliance with by submittal of information in Part B of a permit appli-
cation. Sections 5.0 - 14.0 of this manual will address the reauired infor-
mation items identified in Part 270, identify the corresponding standards in
Part 264, and provide Guidance on how to obtain, prepare, and present in-
form? t ion rec"jired hv Pa-t 270 that will dem^nstr-ate to EPA that t*e facility
is in co^Dlia^ce with the Part 2f£ standards. For our purposes, TaMe 4-1
delineates the 270.16 specific information reauirements to correspondinq 25^
permitting standards specific to hazardous waste tanks.
t
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I I
4-3
TABLE 4-1
Section? of Parts 270 g, 264 Addressed in this Manual
Guidance
Manual Part 270
Sections Sections
e>.l 270.1fi(a)
Corresponding
Sections
Professional encnneer assessment
of structural irt«>ority
5.? ?70.16(b)
5.3 270.16(c)
5.4 270.16(d)
5.5 270.16(e)
fi.O 270.16(f)
~ . ' 27'. ."; r ;,c ,
8.0 270.16(h)
9.0 270.16(O
Tani, dimensions fc capacity
Description of feed systems
Diagram of piping, instrumentation
and process flow
Description of materials antl equipment
for corrosion protection
New tank installation description
S^:c-;a"» ccr id r,~ ~- '. i.r:-:-:- : * ;- :
Reauirements for tank systems not in
compliance with secondary containment
None
None
None
264.191(c)
2W.192(b)(c)(d
"fd)(e)"
r270.1d(c)l*
2«.193(f
Alternate operating practices for tanks 264.193(i)
seeking exemption fro^1 secondary
conta inment
10.0 ?70.16(j) Spills and overfill prevention practices
ll.n 270.U(b)(Fl Inspection Schedules
12.0 270.14(b)(7) Response to unfit-for-use tank systems 26^.19^
13.0 270.14(b)(13)C1osure and post-closure plans 264.197
14.0 270.16(k)
Procedures for tank systems that store/ 264.198 and
treat ignitable.. .incompatible wastes 264.199
These regulatory standards (264.195, 264.196 & 264.197 as revised) are ad-
dressed under the 270.14(b) Part B General Facility Information Requirements.
They are not addressed in the 270.16 revised specific Part B information re-
quirements for tanks.
264.195 - Inspections
264.196 - Response to disposition of leakino or unfit-for-use tank systems
264.197 - Closure and post-closure care
i
C /-.«,, i,- en-, ante
rM 1 1 nr a 1
ir.
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5.1-1
5.1 WRITTEN ASSESSMENT BY A QUALIFIED REGISTERED PROFESSIONAL ENGINEER
OF TANK SYSTEM STRUCTURAL INTEGRITY AND SUITABILITY
FOR HANDLING HAZARDOUS WASTE
Section 270.16(a) reauires that a Qualified reqistered professional
engineer provide a written assessment for each tank system of the system's
structural intearity and suitability for handling hazardous waste. Section
264.191 states the minimum requirements for this report.
At a minimum, a Qualified reqistered professional engineer who assesses
the structural integrity of a tank system must be familiar with tanks and
their causes of failure. The individual must be able to recognize, typically
from field experience, the signs of past or imminent tank system failure.
Such signs include problems with piping and other ancillary eauipment (e.a.,
inadequate seals or valves), residues around a tank from overfills and/or
leakaqe, and corrosion of tank system metal. A reqistered professional
chemical, civil, or mechanical engineer, for example, who is familiar with
tank system design standards, operation and maintenance, and installation
considerations will be able to provide the required assessment of a new,
existing, used, or reused tank system. Because the assessment must contain a
certification of acceptability for storing hazardous wastes, the engineer
musts also be able to access and interpret information on the hazardous waste
contents of the tank system and the compatibility of the contents with tank
lininq and materials of construction.
The Section 264.191 requirements differ for a new tank system, compared
with those required for an existing, used, or reused system. Similarly,
requirements differ for aboveground and underground tanks (see Table 5-1 for
details). An enqineer assessing the structural integrity and acceptability of
a tank system for storing hazardous wastes must address all applicable
regulations. Assistance from tank system manufacturers, leak testers, tank
inspectors, corrosion experts, and relevant literature may be needed to
perform this assessment.
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5.1-2
TABLE 5-1
40 C^P 264.191 Requirements for Hazardous Waste Tanks
_ Tank Syste^ Type __ Applicable Regulation?
New, abovearound, non-metal 264. 191 (a); 264.191 (e)
New, aboveqround, metal 264.191(a); 264.191(c)*;
264.191(e)
New, underqround, non-netal 264.1Ql(a); 264.191(d-e)
New, underground, metal 264.191(a); 264.191(c-e)
Old,** aboveoround, non-metal 264.191 (b)***; 264.191(e)
Old, aboveoround, metal 264.191 (b-c) ; 264.191(e)
Old, underaround, non-metal 264-191 (b); 264.191(d-e)
Old, underaround, metal 264.191(b-e)
'The requirements of Section 264.191(c) are discussed in Chapter 5.5 of
this document.
** "Old" tanks are defined as existing, used, or reused tanks.
*** Section 264.191(b)(5) distinguishes between underground tanks, subject to
a leak test, and aboveground and inground tanks, subject to an internal
inspection.
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i 1
5.1-3
5.1.1 REGULATORY CITATIONS
The qualified registered professional engineer's assessment of a tank
system, required for a RCRA permit application, is defined in Section
270.16(a). "A written assessment by a registered professional engineer as to
the structural integrity and suitability for handling hazardous waste of each
tank system, as required under 5264.191."
5.1.1.1 CITATION: TANK SYSTEM DESIGN, CONTENT COMPATIBILITY, TIGUTNF$S
The professional engineer assessing the structural integrity and
acceptability of a new tank system for storinq and treating hazardous waste
must document the following information, as specified in Section 264.191(a):
"(1) Design standard(s) according to which the tank is constructed;
(2) Design standard(s) according to which the ancillary equipment
is constructed; and
(3) Hazard characteristics of the waste(s) to be handled."
To assess the structural integrity and acceptability of an existing,
used, or reused tank system for storing and treating hazardous waste, the
engineer must comply with Section 264.191(b):
"(1) Design standard(s), if available, according to which the
tank(s) and piping system components were contructed;
(2) Description of the tank system (e.g., size, age, material of
construction);
(3) Hazard characteristics of the waste(s) that have been and will
be handled;
(4) Estimated remaining life of the tank system; and
-------
5.1-4
(5) Results of a leak . test that is capable of detectlna a leak
equal to or greater than 0.05 gallons per hour (for underground
tank systems) or an internal inspection (for above- and
inqround tank systems) performed within the past year."
5.1.1.1.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
Design Standards -- Adherance; to nationally accepted design standards
would convince EPA of the structural integrity of a tank system, as required
by Sections 264.191(a)(1-2). Table 5-2 lists the applicable design standards
for tanks. The permit applicant must demonstrate that all ancillary equipment
complies with similar national design standards PANS I chart to be added,
pendinq copyright approval].
For any nonspecification tank system (i.e., a tank system that does not
comply with the applicable design standards listed in Table 5-2), the engineer
must demonstrate that the system is constructed in accordance with sound
enqineerinq principles and may safely contain hazardous wastes. The engineer
must demonstrate that a tank has the dimensions and thickness necessary to
contain its contents for a given service life (Sections; 264.191 (a,b) (1)). The
calculations must account for internal liquid pressure, internal vapor
pressure, hydrostatic pressure, vehicle loading, and the tank shell
thickness-reducing effect of corrosion (i.e., tank thickness must include a
"corrosion allowance," if applicable).
Bottom pressure is defined as liquid height multiplied by liquid
density. Tank internal vapor pressure is the difference between atmospheric
pressure and the pressure in a tank. A tank designed for contents with a
particular density should not be filled indiscriminately with a material of a
greater density. In cases where it is necessary to store a heavier waste than
a tank was designed for, calculations should be performed to determine the
fill height that will prevent excessive stresses. American Petroleum
Institute (API) Standards 620 and 650, "Recommended Rules for Design and
Construction of Laroe, Welded, Low-Pressure Storage Tanks" (1982) and "Welded
-------
5.1-5
TABLE 5-2
NATIONALLY ACCEPTED TANK DESIGN STANDARDS
Document Number Title Date
AA-ASD-1
AA-ED-33
AA-SAS-30
ACI-344R-70
ACI-350R-/7
AISI-PS-268-685-5M
AISI-TS-291-582-10M-NB
ANSI 896. 1
API 12B
API 12D
API 12F
API 620
API 650
ASME BPV-VIII-1
ASTM D 3299
Aluminum Standards and Data, 1970-71
Enaineerinq Data for Aluminum Structures
Specifications for Aluminum Structures
Desian and Construction of Circular
Prestressed Concrete Structures
Concrete Sanitary Enqineerinq Structures
Useful Information on the Design of
Plate Structures
Steel Tanks for Liauid Storaae
Standard for Welded Aluminum-Alloy
Storaqe Tanks
Specification for Bolted Tanks for Storage
of Production Liauids, 12th Ed.
Specification for Field Welded Tanks
for Storaqe of Production Liquids, 8th Ed.
Specification for Shop Welded Tanks for
Storaae of Production Liauids, 7th Ed.
Recommended Rules for Design and Construction
of Larqe, Welded, Low-Pressure Storaae Tanks
Welded Steel Tanks for Oil Storaae
ASME Boiler and Pressure Vessel Code
Standard Specification for Filament -Wound
19P,
1Q°1
1982
1970
1983
1985
1982
1981
1977
1982
1982
1982
1984
1980
1981
Glass-Fiber Reinforced Thermoset Resin
Chemical Resistant Tanks
ASTM D 4021 Standard Specification for Glass-Fiber 1981
Reinforced Polyester Underground
Petroleum Storaae Tanks
-------
Table 5-2 continued
5.1-6
Document Number
AWWA-D100
NFPA 30
UL 58
UL 80
UL 142
UL 1316
Title
Standard for Welded Steel Tanks for
Water Storage
Flammable and Combustible Liquids Code
Standard for Steel Underoround Tanks
for Flammable and Combustible Liquids
Standard for Steel Inside Tanks for Oil
Burner Fjel
Standard for Steel Abovearouncl Tanks for
Flammable and Combustible Liquids
Standard for Glass-Fiber-Reinforced Plastic
Underground Storage Tanks for Petroleum Products
Date
1984
1984
1976
1980
Table 5-2 standards are continually being updated. it is UD to trie permit
applicant to demonstrate compliance with the most recent set of applicable
desion standards. Check with the following oraanizations for more information
on standards:
The Aluninum Association (AA)
818 Connecticut Avenue, N.W.
Washington, D.C. 20006
(202) 862-5100
American Concrete Institute (ACI)
Box 4754
Redford Station
Detroit, MI 48219
(313) 532-2600
American Iron and Steel
Institute (AISI)
1000 Sixteenth Street, N.W.
Washington, D.C. 20036
(202) 452-7190
American National Standards
Institute, Inc. (ANSI)
1430 Broadway
New York, NY 10018
(212) 354-3300
American Petroleum Institute (API)
1220 L Street, N.W.
Washington, D.C. 20005
(202) 682-8000
American Society for Testing and Materials
(ASTM)
1916 Race Street
Philadelphia, PA 19103
(215) 299-5400
American Society of Mechanical Engineers (ASME
United Engineering Center
345 East 47th Street
New York, NY 10017
(212) 705-7722
Publications: (201) 882-1167
American Water Works Association (AWWA)
6666 West Ouincy Avenue
Denver, CO 80235
(303) 794-7711
-------
5.1-7
Table 5-2 (continued)
National Fire Protection Association Underwriters Laboratories, Inc. (UL)
(NFPA) 333 Pfinqsten Road
Batterymarch Park Northbrook, IL 60062
Ouincy, MA 02269 (312) 272-8800
Publications: (800) 344-3555
-------
5.1-8
Steel Tanks for Oil Storage" (1980), respectively, provide extensive
inform: -n on design calculations. The American Society of Mechanical
Engineers (ASME) "Boiler and Pressure Vessel Code" (1980) also provides
guidelines on tank design.
Usina best engineering judgement, the professonal enoineer must determine
whether a tank has an adequate margin of safety for tank thickness. Tanks
designed according to standards or codes often have inherent theoretical
safety factors in the ranae of 3-5. The enaineer should remember that
fiberglass reinforced plastic (FRP) tank designs reauire that backfill provide
much (up to 90 percent) of their structural support. Uniform backfill suooort
is also important for steel tanks. The operatinq temperature ranae must ^slso"
be appropriate for the tank construction materials.
For new tanks with integral seconJary containment, the Steel Tank m
Institute has developed guidelines for the design and construction of steel
double-walled tanks, entitled "Standard for Dual Wall Underground Steel
Storaae Tanks" (1984). This standard only applies to double-walled tanks with
300° of secondary containment, whereas EPA reauires 360° of secondary
containment for a double-walled hazardous waste storaae tank. A similar
guideline has not been developed, however, for FRP double-walled tanks.
Manufacturers' data and/or UL design approval will have to be used to convince
EPA of the structural integrity of such a tank. ("Underwriters Laboratories,
Inc. is currently in the process of developing double-walled tank standards.!
Tank venting must be shown to be adequate. The vapor pressure within a
tank must either be maintained under atmospheric pressure or within the
pressure limitation of the tank design. Normal vents are needed for
atmospheric and low-pressure tanks that are not constructed to handle
excessive pressure or vacuum build-up. High-pressure tanks require only
emergency vents. Venting capacities are based on maximum emptying, filling, M
thermal inbreathing, and outbreaking (this depends on the vapor flash point)
rates.
-------
5.1-9
Venting can be accomplished under normal operating conditions with open
vents, pressure vacuum valves, pressure relief valves, and pilot-operated
relief valves, with each type generally designed for specific services. Open
vents with a flame arresting device (such as a metal screen) should be used
only for liquid wastes with flash points above 100°F and tanks with a capacity
less than 2500 gallons. Pressure vacuum valves are designed for atmospheric
storage tanks containing low-boiling point liguids. Pressure relief valves
are used chiefly for liquid storage and generally should not be used for gas
or vapor service. Rupture discs and resilient valve seats are often used i-n
conjunction with pressure relief valves for storage of corrosive, viscous, and
polymerizable liquids that can damage valves. Pilot-operated valves are
generally used when the relief pressure is near the operating pressure, ana in-
low-pressure tanks, but not those with viscous liquids or liquids with vapors
that can polymerize.
Floating roof tanks also prevent vapor build-up. For emergency venting,
a tank may have a roof-to-shell weld attachment designed for early failure
during pressure build-up, larger or additional normal vents and/or gage
hatches, or manhole covers that open at a designated pressure.
Vent sizes should be determined according to standards such as API
Standard 2000, "Venting Atmospheric and Low Pressure Tanks" (1982). NFPA
Standard 30, "Flammable and Combustible Liguids Code" (1984) also provides
vent design information. Vent piping for an underground tank should extend
several feet above ground level to prevent fumes from concentrating near the
ground. Such piping should be a minimum of two feet higher than adjacent
buildings. Rain caps on vent piping are advisable.
Nonspecification tank appurtenances must also have the appropriate
strength to handle the maximum internal stresses expected (Sections
264.191(a)(2) and 264.191(b)(1)). The engineer must assess the ability of a
tank's ancillary equipment, including piping, valves, fittings, pumps, etc.,
to handle the waste materials (liquid, slurry, or vapor), in the volumes
-------
5.1-10
expected. Any manufacturer's test results demonstrating the strength of a
particular tank system component will helo convince EPA of the system's
structural integrity. That is, the engineer should be able to demonstrate
that the maximum stress (taking into consideration ambient temperature and
pressure) to which a component will be exposed is less than the maximum
allowable design stress, with an adeguate safety factor.
Characteristics of Waste -- The engineer must assess the "hazard
characteristics of the waste(s)H and the ability of a tank system to handle
such waste(s). EPA interprets Sections 264.191 fa,b) (3) to mean that a tank
system must be compatible with its contained waste or mixture of wastes.
Thus, any portion of a tank system (e.g., tank linina, tank outer shell,
piping, valves, fittings, pumps) that contacts waste must not deteriorate in
the waste's presence. Linings are often added to a tank to ensure
compatibility of tank contents with the tank wall.
In compliance with Section 264.13, the owner or operator of a tank must
have obtained a detailed chemical and physical analysis of the contained
waste. The engineer must use this analysis, alonq with his/her knowledqe of
the ignitability (Section 261.21), corrosivity (Section 261.22), reactivity
(Section 261.23), and toxicity (Section 261.24) of the waste stream(s), to
determine if the stream(s) is compatible with its tank system. Table 5-3
describes the impact of these factors on tank design. Data from the Chemical
Engineers' Handbook, the National Association of Corrosion Engineer (NACE),
tank, lining, and resin manufacturers, facility tests and other relevant
sources may be used to convince EPA of the compatibility of stored waste(s)
and its container, as reguired under Sections 264.191(a,b)(3). See Section
14.0 for more information on waste compatibility.
Table 5-4 presents the compatibility of common tank materials of construe-
tion with various chemicals. Generally, the assessment of compatibility for
purposes of Table 5-4 was conservative, e.g., the internal corrosion rate for
metals had to be less than 2/1000 inches per year. This table is, however,
-------
5.1-n
Table 5-3
Impact of Selected Properties of Wastes on Tank Design
Waste Proc-.--:v
Impact on Tank Oesion
Ignitability
Corrosiveness
Reactivity
Toxicity
Generally, steel must be used for the tank
and the tank must be enclosed.
A material of construction for the tank
must be selected that has a low corrosion
rate, or an effective lininq or coating
material must be used that is cor-oatible
with the waste (and ooeratinq conditions).
None, unless reactive with, carbon dioxide
in the air, in which case the tank should
be enclosed.
lank should Generally be enclosed (unless
toxic components are not volatile or
components are of low volatility and are
not toxic at low concentrations).
-------
5.1-12
Table 5-4
Compatibility of Materials of Construction with Various Chemicals
Minerals
SuU. : acid'1 )
Hydrochloric acid(^)
Nitric acid
Phosphoric acid
Oraanic Acids
Acetic acid
Bases
Sodium hydroxide
Ammonium hydroxide
Aqueous Salts
Calcium chloride
Sodium sulfate
Copper sulfate
Ferric chloride
Sodium hypochloride
Stannous chloride
Sodium chloride
Alum
Compatible With
FRp(2)
Mild Steel
Rubter-1 ined
FRP
FR P ( 4 )
FRP
FRP
FOP
Mile steel (5)
Mile steel (5)
FRP(6]
FRP
FRP
FRP
FRP
Special metal alloys
Noble metals
Stainless steel to 50*
FRP
FRP
Incompatible With
Mild steel
Mild steel
Mild steel
Mild steel
Mild steel1'5'
Mild steel (5)
Mild steel (?)
Mild steel
Mild steel
Mild steel
Mild steel
FRP
Mild steel
Mild steel
-------
Table 5-4 (continued)
5.1-13
Compatible With
Incompatible with
Solvents
Perchloroethylene
Carbon tetrachloride
Ethyl alcohol
Methyl ethyl ketone
Acetone
Miscel laneous
Benzene
Hexane
Gasol i
Anil ine
Nitrobenzene
Phenol
Chlorobenzene
Naphthalene
Benzoic acid
Diethyl amine
Formaldehyde
FRP(8)
Mild steelOO)
FRp(13)
Vild steel(]6)
Mild steel
FRP
Stainless steel
FRPH9)
Mild steel
Mild steel
Stainless steel
Mild steel
Stainless steel
Mild steel(2°)
Special metals
(nickel-base alloys)
Mild steel(?2)
FRP
Stainless steel
Mild steel
Mild steel
Stainless steel
Mild steel02)
Mild
Mild steel
FRP
FRP
Mild steel
FRP
FRP(20
Mild steel
Mild steel
-------
5.1-14
Table 5-4
NOTES:
(1) Needs the attention of a corrosion specialist. FRP is good up to 70
percent concentration. Mild steel (M.S.) is good for concentrations
from 93 to 98 percent.
(2) Fiberglass-reinforced piastres (FRP) have been considered here. How-
ever, there are fiberglass-reinforced epoxy resins available that are
not considered in this table.
(3) FRP is good to 30 percent concentration. No oraanic solvents should be
present. The National Association of Corrosion Engineers (NACE),
Houston, TX has a graph for the compatibility of various metals for HC1
use.
(4) FRP is good to 15 percent concentration.
(5) M.S. is good only to 25°C. 316 Stainless steel (S.S.) is recommended
for service conditions about. 25°C.
(6) FRP is good to about 50 percent concentration.
(7) M.S. is incompatible after about 5 percent concentration at 100°C.
(8) FRP is good to about 25°C.
(9) FRP is good to about 125°C.
(10) FRP is good for 95 percent concentration and 21° to 66°C.
(11) FRP is good from 10° to 35°C.
(12) M.S. is incompatible for concentrations below 100 percent.
(13) FRP is good for 10 percent concentration and 21° to 79.5°C.
(14) M.S. is Incompatible for concentrations below 100 percent.
(15) FRP is good from 10° to 32°C.
(16) M.S. is aood for 100 percent solvent to 100°C.
(17) NACE did not have data for gasoline; therefore, the data were obtained
from the Petroleum Processing Handbook by W.F. Bland and R.L. Davidson
(1967), pp. 5-8.
(18) S.S. is good to 100 percent concentration.
-------
5.1-15
Table 5-4 NOTES (continued)
(19) FRP is good for 5 percent concentration and 21° to 52°C.
20) M.S. is good to TOO percent concentration.
(21) FRP is good for only 100 percent concentration and 21° to 27°C; there-
fore, it is listed as incompatible
(22) M.S. is qood only at 100 percent concentration and up to 100°C.
-------
5.1-16
just a guideline to waste/construction material compatibility and additional
evidence of compatibility may be required of the permit applicant by the
Regional Administrator.
Although FRP tanks are generally referred to in a way that denotes a
single type of storaae tank they can, in fact, actually be fabricated from a
wide variety of plastic resins. The selection of plastic resin depends uoon
the material to be contained and the conditions of storaqe. Most FRP tanks
now in use are constructed from isophthalic polyester resin. Because the
resins used for FRP construction have chanqed over time, it is imprudent to
reuse an FRP tank of unknown origin and aae unless the prior use of the tank
is known and the tank manufacturer is consulted on the compatibility of the
tank resin with the new stored waste.
Tank Description -- For existing, used and reused tank systems, Section
264.191(b)(2) requires that the enqineer provide a description of a tank
system, documenting (at a minimum) the size, age, and materials of
construction of the system. Liners, coatings, valves, fittings, bushings,
cathodic protection devices, etc., should all be described. Any blueprints or
scale drawings should also be included in the enqineer's submission.
Leak Tests -- Section 264.191(b)(5) requires the enqineer to obtain the
results of a leak test, performed within one year prior to the assessment, on
an existing, used, or reused underground tank and its piping. If the engineer
has been certified by a manufacturer of leak test equipment to perform the
test himself, he/she may do so; otherwise, he/she must obtain the services of
an experienced leak tester. An underground tank system that has been tested
and shows no leakage down to 0.05 gallons (190 ml) per hour (the NFPA
definition of a Precision Test, see NFPA Bulletin 329), is assumed to be
nonleaking. ^
-------
5.1-17
EPA is currently involved in a research effort to evaluate the
effectiveness of different leak testino technolooies. A preliminary report
entitled "Underground Tank Leak Detection Methods: A State-of-the-Art
Review," has recently been published by EPA's Hazardous Waste Engineering
Research Licoratory, Cincinnati, Ohio. Table 5-5, reprinted from this
document, compares the different Teak testing technologies.
The selection of a leak testing device must consider how the design of
the device accounts for volume changes in tank contents caused by the
following factors:
0 Temperature chanaes during testing and temperature gradients --
within a tank or piping,
0 A hiqh water table causing ingress of water,
0 Tank end deflection caused by increased pressure in a tank
durina testing,
0 Evaporation losses, and
0 Volume changes of trapped air and vapor pockets in a tank and
piping.
Some of the above factors can potentially contribute large errors to leak
testing measurements; hence, the contributions of such troublesome factors to
leak testing calculations must be minimized or eliminated by the design of a
leak testing system. A discussion of each of these factors follows below.
Temperature. The liquid or sludge content of a tank will generally, to a
greater or lesser extent depending on composition, expand in size with
increased temperature and contract with decreased temperature. For example,
the coefficient of expansion per degree Fahrenheit for gasoline ranges from
0.0006-0.00068 (see Table 5-6). That is, in a 10,000 gallon gasoline tank, a
volume change of 6-6.8 Gallons will be observed with an overall 1°F
temperature change. Thus, in a 10,000 gallon gas tank, it is necessary to
maintain or measure the tank temperature to approximately 1/100 of a degree
(Fahrenheit) over a one-hour period to measure a 0.05 gallon hourly leakage
-------
5.1-18
Table 5-5
General Information on Leak Testing Devices
Volu-netric Measures
Method
Principle
Claimed
"flccuracy
Tank
''on.
Ainlay Tank Tegrity
Tttlin|
AJICO HTC Underground
Tank Leak Detector
Certi-Tec Tcating
Ethyl" Tank Sentry
ZY-CMEK Leak Detector
fluid-Static (Stand-
pipe)
Preaaure eaturevent by
cotl type Mnooeter ,
decereuiic product level
change in propane
bubbling eyate*
Level change ettaeureewnt
by float and light tenaing
yatea
e Honttorf preaaure ehangea
reiuleing fro* product
level changt*
Level changt magnification
bjr a "J" tuse a>ano»etcr
« freiaure a>e.iaure« Hcaaure rat«t »f voluaM
change
0.02
0.05
0.05
Senai 11ve to
0.02 iache a
level change
Leaa than 0.01
Croaa
H II a tank e
before a teat
Adjuat the le
(6-74 percent
Hoot
o deliver tea
houri prior it
teat
Pill up four *
prior to let
utualty teat I
night
fill the tank
to teat
Heath Petro Tite Tank
nd Line Telling (Kent-
Moore)
Heliu* Di(ferentlal
Prctturc Teecina.
e Preaaurite t\ tyateei by a
atandpipe
Keep the level conatant
by product iiddition or
removal
Neaaure voluaie change
Product circulation by
puap
e Leak detection by differ-
ential preaiure change in
an e«pty tank
Leak rale eatietation by
lernoulli'a equation
Leaa than 0.05
Lean than 0.0)
ilI the tank
Co a teat
J
Seal the port
the atakoaptieri
eapty the tanl
-------
5..1-19
Table 5-5 (continued)
General Information on Leak Testing Devices
Volumetric Measures
Method
Principle
Claimed
Accuracy
Tank
Preoarat ion
Leak Lokator Ten
Hunter-For«erIy
Sun**rk Leak
Oelec tion
"Principle of Buoyancy"
The apparent Ion in
weight of any object
submerged in a liquid
ii equal to the weight
of (he displaced volu*v
of liquid
0.0) even at
product
level at
the center
of a tank
Typically fill th
tank before ttati
(if it ta pottibt
to fill a tank by
the product) -
Hooney Tank Te»t
Detector
PACE Tank Tetter
e Level change eaiurenent
with a dip itick
Hagnification of pretiure
change in a icaled tank
by uting a lube and bated
on aianoetcter principle
0.02
Lett than
0.0)
Pi II tht tank 17-
hour i pr i or to a
left
Pi I I the tank I
hourt prior to
teit
Seal all the pc
eicept fill ptf
PALO-2 Leak Detector
Pneuaatic Teiting
Tank Auditor
Two-Tube Later Inter-
faroMter Syateat
Pretturne tyttc* with
nitrogen at three di f-
ferent prtaaurea
Level eaturecMnt by
an electro-optical
device
Catiatat* leak rate
bated on the ait* of
leak and pretiure
difference acroat the
leak
Pretiurite tytto with
air or other gat
Leak rat* eteatureawnt
by chang* in pretture
"Principle of luoyancy"
Leas than 0.0)
Level ehang* etaatureaent
by later b*aa) and it*
reflection
Crott
0.00001 in th*
fill pip*
0.0) at th*
center of
10.5-foot-
diaamer tank
Lett than 0.0)
Pill th* tank 24
hour a prior to a
tett. All port.
utt be h*r*t«tic-
ally tea led
Seal the port!
Hen*
on*
-------
I I
5.1-20
Table 5-5 (continued)
Method
Acoustical Monitoring
Syttea (AHS)
Leybold-Heraeus HeliuB
Detector . Ultraiesl H2
D«ni son He I I u>
TRC Rapid Leak Detector
lor Underground Tanks
and Pipe*
Ultrasonic Leak
Otttclor (Ultrasound)
VeeuTect (Tanknology)
General Information on Leak Testing Devices
Nonvolumetrlc Measures
Principle
Sound detection of
vibration and elastic
waves |*ner*ted by
leak in pressurised
lyste*) by DkCrO|;«n
Trt*n|ul«lion tuch-
nique lo detect leek
lac it ion
Rapid diffuiivil.y of
he Iiu«
Mil tracer |tn, with
product* at the botto*
of the tank
Detect heliu*) bf a
ini f f tr tin spctc-
trooctcr
Rapid diffuaivity of
he Iiu»
Differential pressure
caaureaent
Heliua detection out-
aide a tank
Rapid diffusion of
tracer gat
Mil a tracer (
vith product
Detect tracer gas
by a aniffer saaa
pectroMttr uiing
a vacuua puap
Vacuu* the tytte*
(> pai)
Scanning entire tank
vat I by Ultrasound
device
Note the eound due
to leak by head-
phones and register
on a aveler
Vacuud applicition at
higher than product
static head
Datect bubbling ooise
Accuracy
Doe* not provide
teak rate
Detect leak a*
low a* O.Ot gal-
lon* per hour
Does not provide
leak rate
lio I iu« (.onId leak
through O.OOS inches
keak site via)
Provide the Mii-
ua possible leak
baaed on the aiae
of the leak (do«s
not provide Itak
rate)
Heliusi could teak
through 0.005 inches
teak site
Duo* mot provide
leak rate
Tr*c«r gas could
Irak ihrouKh
O.OOS I nine* Irak
site (J|)
DoeI not provide
the leak rate
A leak a* low a*
0.001 gallona per
hour of air could
be detected
A leiik through
0.005 inchea
could be
detected
Provide approci-
att Itak rate
Tank
Pr-eparat ion
leal al I pore
prior to a ti
a Seal all pori
prior to~ a n
Monitoring hi
a &eal all por
a Moni tor ing h
teal alI por
prior to a I
Monitoring t
teal ail pc
«3 Capty the t
feal all pc
-------
5.1-21
Table 5-6
Thermal Expansion of Liquids*
Acetone
Amyl acetate
Benzol (benzene)
Carbon disulfide
Diesel fuel
Ethyl alcohol
Ethyl ether
Ethyl acetate
Fuel Oil #1
Fuel Oil #2
Fuel Oil #3
GASOHOL
.10 Ethyl + .90 Gasoline
.10 Methyl + .90 Gasoline
Gasoline
Hexane
Jet fuel (FP 4)
Kerosene
Methyl alcohol
Stove oil
Toluol (toluene)
Water at 68°F
Volumetric
Coefficient
of Expansion
per Degree F
0.00085
0.00068
0.00071 .
0.00070
0.00045
0.00062
0.00098
0.00079
0.00049
0.00046
0.0004
0.000674
0.000684
0.0006-0.00068
0.00072
0.00056
0.00049
0.00072
0.00049
0.00063
0.000115
* These are average values and may vary. It is necessary to use the appro-
priate API hydrometer in order to get the proper coefficient of expantion.
Source: Heath Consultants, Inc., Stoughton, MA
-------
5.1-22
rate. The necessity for minimizing temperature changes is the reason why
underground, not aboveground or inground tanks, can be leak tested with
reasonable accuracy. If a leak testing device compensates for temperature
changes using the coefficient of expansion of the tank contents, the tester
must ascertain accurately what material the tank contains, including the
respective volumetric percentages of a mixture of materials. Waste layering
in a tank (because of immiscibility) can also affect leak test measurements.
The temoerature layering in an underground tank produces anothe-" leak
testing measurement difficulty. Underground tanks can have numerous
temperature layers, since they are never in perfect equilibrium with the
surrounding environment, nor are tank interiors ever entirely equilibrated.
Hot days and cold nights can alter tank temoeratures; additionally, convection
currents cause warmer contents to rise to the tops of tanks, while colder -
contents move downward. There is no such thing as a single "tank
temperature." The properties cf tank contents that determine the overall
temperature effects (expansion, contraction, temperature layer gradients) are
the coefficient of expansion with temperature, the heat conduction capability,
and the viscosity (related to settling time following a disturbance).
Water Table. A high water table, i.e., one in which water can ingress
into an underground tank, can cause a state of hydrostatic equilibrium whereby
there is no net flow from the tank, though there may be holes. Leak detection
devices must account for this apparent absence of leakage, through detection
of water ingress. If there is not a hydrostatic equilibrium situation and
there 1s a net water flow into a tank through holes, that should also be
detected.
Tank End Deflection. If a leak test increases the hydrostatic pressure
within a tank, the tank ends will deflect, bulging outward with the increased
pressure (see Table 5-7). The rate of tank capacity increase, however, slows m
over time and this fact can be used to extrapolate when tank end deflection
has slowed enough that it will not cause a significant error in a leak test
measurement.
-------
5.1-23
Table 5-7
Total Force on Tank Ends
Formula: Force = Area x Pressure (Ibs./sq. in.)
Tank
Diameter
48"
64"
72"
84''
96"
Total Force
1 Psi
0.
1.
2.
2
3.
9
6
0
Q
,6
2 Psi
1.
3.
4.
5.
7
8
2
0
K
w
.2
in Tons at:
3 Psi
2.
4
6.
8
10
7
8
,0
, -t
.8
4 Psi
3.
6.
8.
11
14
6
4
.0
0
. L.
.4
5 Psi
4.
8.
10.
14.
18.
5
0
,0
,0
.0
Source: Heath Consultants, Inc., Stoughton, MA
-------
5.1-24
Evaporation. During the test period, volume changes caused by
evaporation must be compensated for in leak test calculations. Evaporation
and condensation rates are enhanced by mixing additional product, a necessary
step for some leak testing systems, with product already in a tank at a
different temperature.
Trapped Air and Vapor Pockets. If a tank is filled for testing purposes,
the tank and its piping may contain an unknown amount of air. This air can
compress and expand readily with pressure changes, causinq apparent volume
changes. Additionally, a tank content's mass and the spring-like effect of
any trapped air can produce an oscillating system with a resonant freauency of
approximately two Hertz and a decay time of several minutes.* The oscillation
can be initiated by ground motion, such as from traffic, and by addinq Droatict
to a tank.
Vapor pockets form in three ways:
0 At the high ends of a tank when the tank is not perfectly level,
0 When vapor is trapped in the top of a manway, and
0 When vapor is trapped at the tops of a drop tube.
If a vapor pocket is released to the atmosphere when it expands because of
decreased barometric pressure or increased temperature, a sensor measuring
liquid level will record a drop if liquid fills the pockets. Similarly, if a
vapor pocket is compressed because of increased barometric pressure or
decreased temperature, the liquid level will appear to rise.
"*Grundmann, Werner,"Pald-2 Underground Tank Leak Detector and Observation
of the Behavior of Underground Tanks," Underground Tank Testing
Symposium, May 25-26, 1982, Petroleum Association for the Conversation o?
the Canadian Environment, Ottawa, Canada, p. 17.
-------
5.1-25
SIudge. The presence of sludge on the bottom of a tank can seal over a
failure in the vessel and thus hide a leak. Because the sludge is not an
integral component of the tank, it is not expected to continue to seal the
leak. In addition, sludge may lead to inaccurate readings in some leak
testing designs. With proper cleanina and safety procedures, a sludge layer
can be removed.
Pressure Testing can determine the structural integrity of tanks and
piping. These structures may be hydrostatically pressure tested with water,
at 150 percent of design pressure. A pressure gage identifies leaks in the
closed system, by detecting a pressure decrease. Pressure testing with gases
is generally less reliable because the sound of gas escapino, rather than a
gage, is used to detect leaks. Existing, used piping may be dynamically
tested. API Publication 1110, "Recommended Practice for the Pressure Testing
of Liquid Petroleum Pipelines" (1981), provides details on hydrostatic and
dynamic testing of piping.
In general, leak tests must be performed by specially trained operators.
Prices, time required, and testing conditions differ for the various devices.
The engineer should consult materials from manufacturers and from certified
test operators who serve the locale of a particular tank system for further
details on the different test devices.
Internal Inspections -- For aboveground and inground existing, used, and
reused tank systems, an internal inspection performed within the year prior to
the engineer's assessment is necessary, according to Section 264.191(b)(5).
It is often appropriate to coordinate this inspection with the time when a
tank system is taken out of service for routine preventive maintenance. API's
Guide for Inspection of Refinery Equipment, particularly chapters X-Xlll and
XV-XVI, is a useful reference for tank system inspection.
-------
5.1-26
An internal visual inspection of a tank may be carried out by the
engineer and/or by an experienced tank inspector to detect potential sources
of leakage, such as corroded, cracked, or broken equipment. See Section
11.1.5.1.2 for details on conductinq internal inspections.
Remaining Life -- Given the results of leak testing and internal
inspection and the information obtained for Sections 264.191(b)(1-3), the
engineer will be able to estimate the remaining life of an existing, used, or
reused tank system, as reauired under Section 264.191(b)(4). This estimate
will be tied to the length of the Part B permit. The engineer must be able to
recognize a tank system that is likely to fail in the very near future:
showing signs of extensive corrosion and/or placement in a corrosTve
environment, improper installation practices, lining bulges or deterioration,
having a history of repairs, etc.
5.1.1.2 CITATION: PROTECTION FROM VEHICULAR TRAFFIC
Because portions of a tank system that are underground may be subject to
the damaging effects of vehicular loads, Section 264.191(d) requires that a
qualified registered professional engineer assess the design and/or
operational measures that protect a tank system from these loads. As stated
in Section 264.191(d):
"For underground tank system components that are likely to be
affected by vehicular traffic, a determination of design or
operational measures that v/ill protect the tank system against
potential damage."
5.1.1.2.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
In order to avoid excessive loads on portions of a tank system that can
lead to premature structural failure, the design (including installation) of a
tank system must be able to support expected vehicular loads. Cover in
traffic areas should be a minimum of 36 inches; 30 inches of compacted
backfill and 6 inches of asphaltic concrete is suaop«t,1jrlr,1cr not less than 18
-------
t I
5.1-27
inches of compacted backfill plus at least 6 inches of reinforced concrete or
8 inches of asphaltic concrete. A larger tank may require even greater cover
depth. Baltic or reinforced concrete paving over tanks in traffic areas
should extend at least one foot beyond the perimeter of a tank in all
directions. An underlying synthetic, impermeable layer below the pavement is
recommended. If the depth of cover is greater than a tank's diameter, the
tank manufacturer should be consulted to determine if tank structural
reinforcement is needed. A minimum horizontal backfill clearance in all
directions of 1? inches is recommended for steel tanks and 18 inches is
recommended for FRP tanks.
Operational measures that avoid excessive vehicular loads on a tank
system include instituting a weight limit on vehicles traveling above a tank
system and/or construction of guard rails or barricades around tank system
components susceptible to damaae from such loads. The professional engineer
assessing a tank system design will be able to judge the effectiveness of the
methods used to prevent damage from vehicular traffic.
5.1.1.3 CITATION: FOUNDATION LOADS AND ANCHORING
A tank system foundation must be able to support the load of a full tank
and tank anchoring must prevent flotation and dislodgment. Section 264.191(e)
requires that a qualified registered professional enqineer ascertain that:
"(1) The foundations will maintain the load of a full tank; and
(2) Tank systems will be anchored to prevent flotation and/or
dislodgment where the tank system is placed in a saturated
zone, or is located within a seismic fault zone subject to the
standards of §264.18(a)."
5.1.1.3.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
A qualified registered professional engineer assessing the integrity of a
tank foundation and its ability to support a full tank load must be familiar
with the characteristics of the surrounding ground environmc-*- (~J " 'story
of similar structures in the vicinity. This requirement aoolles to all tvoes
-------
5.1-28
of tank systems: aboveground, inground, and underground. Following uniform
settlement, piping must not be st-ained and there should be no inaccuracies in
gaging. Additional information on assessing foundation integrity is contained
in API Standards 620 and 650, "Recommended Rules for Design and Construction
of Large, Welded, Low-Pressure Storage Tanks" (1982), Appendix C, and "Welded
Steel Tvv« for Oil Storage" (Revised 1984), Appendix B, respectively.
An underground or inground tank that may be subject to flotation and/or
dislodgment because of its placement in a zone that may be saturated at some
time (from seasonal precipitation changes, a flood plain location, stormwater
run-off, etc.), must have its anchoring system assessed for adeauacy and
structural integrity. Manufacturers' recommendations on anchoring techniques
should be followed. Tank vents and other openings that are not liquid-tight
must be located above maximum water level.
Normal paving and backfill usually provide adequate restraint for tanks.
Because of their additional weight, steel tanks are less susceptible to
flotation than FRP tanks and smaller tanks are generally less buoyant than
larger tanks. If there is any question on whether or not weighting or
anchoring is necessary, estimates of expected ground water levels and
calculations of buoyant forces should be made by a professional enqineer.
Buoyancy tables for FRP tanks are available in the Owens-Corn ing "Fiberglass
Underground Tank Installation Techniques Manual." Tank manufacturers should
be consulted for buoyancy information on steel tanks. All FRP tanks over 12
feet in diameter must be anchored, whether installed in a wet site or not.
If additional anchoring is necessary, buoyancy may be offset by the use
of hold-down pads, prefabricated deadmen, or mid-anchoring. These devices are
described as follows:
0 Hold-down pads are reinforced concrete (minimum of 8 inches)
pads that provide firm foundations for tanks. The pads also
offset the tanks' buoyancy. These pads should extend at least
18 inches beyond the sides of tanks and one foot beyond the
ends. Pad thickness is determined by maximum water level, tank
size and weight, burial depth, and paving. At least 12 inches
of material should separate tanks from hold-down pads.
-------
5.1-29
0 Deadmen anchors are prefabricated beams of reinforced concrete
with straps and cables attached. Anchoring straps and cables
must not damage tanks; these devices may be separated from
tanks by usinq portions of rubber tires, for example.
0 Mid-anchoring consists of placinq unreinforced concrete over
the top 3/8 of tanks. At least 2 feet, 6 inches of backfill
should be placed above these tanks and 6 inches of reinforced
concrete at grade. Tanks must be covered with nonconductive
material to maintain electrical isolation for cathodically
protected tanks and to protect coatings and tank shells from
damage from the concrete.
Figure 5-1 illustrates each of these anchoring techniques.
All anchoring devices (bolts, etc.) must be adequately protected from
corrosion and other forms of deterioration and they must not damage the tank
system in any way. Anchoring straps must be uniformly tight and spaced so the
tank load will be evenly distributed. Anchoring straps on a steel tank must
be separated from the tank by a pad made of inert material. The pad should be
at least two inches wider than the hold-down straps, to prevent coating
scratches and to ensure electrical isolation of the tank and its anchoring.
FRP straps must be aligned on the tank ribs, not between the ribs.
Any tank system in a location where compliance with Section 254.18(a)
must be demonstrated (see Appendix VI of Section 264, "Political Jurisdictions
in Which Compliance with 5264.18(a) Must Be Demonstrated"), is required under
Section 264.191(e) to be anchored appropriately to prevent dislodgment.
Anchoring methods that may be used are the same as those described in this
section to prevent flotation. API Standard 650, "Welded Steel Tanks for Oil
Storage" (Revised 1984), Appendix E, provides information on seismic design
for storage tanks and piping, including details on -anchoring specifications
and calculations.
-------
5.1-30
-igure 5-1
Anchoring Techniaues
Straps and
connector*
Hold-down pad
6 In. reinforced
concrete
2ft.6ln. backfill
Reinforcement
to prevent
aeparatlon
Protect tank she)
and coating
Streps end
connectora
Deadmen anchors
-------
5.1-31
5.1.2 MAJOR ISSUE POINTS
1. Is the registered professional engineer qualified to perform a tan*
system assessment? Are adequate references and resources (e.g.,
leak/testers, corrosion experts) available?
2. Is the tank system designed appropriately for its intended usage?
3. If the tank system is existing, used, or reused, have leak tests or
internal inspections proved the tank is nonleakino?
4. Is the tank system properly designed to accommodate vehicular loadsT
a full tank, high ground water conditions, and seismic activity?
-------
t I
I k
5.2-'
5.2 DIMENSIONS AND CAPACITY OF THE TANK
5.2.1 Regulatory Citation
Information on the dimensions and capacity of a tank must be included in
Part B of the permit application, as specified in:
"§270.16(b), dimensions and capacity of the tank;"
Part 264 of the regulations does not specify any regulatory standards
with which tank dimensions or capacity must comply.
5.2.2 Guidance to Achieve the Standard
5.2.2.1 Ger e'-a1 . The intent of reauiring submittal of tank dimensions
and capacity as delineated in §270..16(b) with Part B of the permit application
is to supply information to accurately identify and classify any tank
described within the application and to insure that the tankage is properly
designed and constructed in accordance with recognized guidelines and
standards. The information on dimensions and capacity should be provided in
addition to the storage or treatment volumes of the tanks given in Section
III, Processes - Codes and Design Capacities, of Part A of the application.
Each individual hazardous waste tank should be described independently in Part
B, with the dimensions and capacity of each tank clearly indicated.
As noted above, there are not standards in Part 254 with which the
dimension and capacity information must comply. Howeve^, it is suggested that
a general written description of each tank incorporate the following
information (easily provided in tabular form):
0 Shape of tank;
0 Material of construction;
0 Diameter, in feet;
-------
5.2-2
0 Height and length, in feet;
0 Circumference, in feet;
0 Nominal capacity, in gallons;
0 Maximum capacity, in gallons;
0 Wall thickness (bottom plates, shell plates and roof, or shell
only, as applicable);
c Description of appurtenances (type, size, and location for all
nozzles, manholes, and drawoffs); and
0 Stairways, supports, fittings, platforms, and walkways.
Each general tank description should be accomoanied b_y detailed scale
plan and elevation drawings which specify all dimensions of the tank.
Examples of such drawings can be found in Figures 5.2.1 through 5.2.3.
In adaition, a cauge chart which indicates capacity per foot of length
(or height) in a tank with a specified diameter, should be provided if
available. For cylindrical tanks, a standard table such as the one provided
in Table 5.2.1 is applicable. For irregularly shaped tanks the manufacturer
should provide a similar table which is specific for that particular tank.
5.2.2.2 Aboveground Tanks. Aboveqround steel tanks can be either
shop-welded (fabricated by the manufacturer in a variety of standard sizes and
purchased ready-to-install) or field-welded (constructed on the site by
rolling steel plate and welding it together according to predetermined
specifications). Shop-welded tanks are generally less than 12 to 15 feet in
diameter; tanks which have diameters greater than 12 to 15 feet are usually
field erected. Fiberglass or fiberglass reinforced plastic (FRP) tanks are
always purchased ready to use from the manufacturer, and are available in a
wide variety of shapes, dimensions, and capacities.
-------
I I
5.2-3
Figure 5.2.1
Tank Dimensions
DRAIN-LINE
CONNECTION
,8".x-CLI-ANOUT (SEE PAR 319)
AME PLATE SEE PAR 62)
- NEUTRAL
EXTERIOR ANGLE INTERIOR ANGLE
SOME ACCEPTABLE METHODS
FOR
LE DEC* ATTACHMENT
(SEE PAR J.!2 AND 3.17)
VENT-LINE 'CZ1
CONNECTION
TH!EC-HATCH Cw'CL-T
/ OV
LINE CONNECTION
PILL-LINE
c-. CONNECT CN
'E-L'NE CONNEC"
VENT-LINE
CONNECTIO_N.
VP|CAL DOME DESIGN
-£v OVERFLOW-LINE
"^CONNECTIONS
WALKWAY
-e='ACKET
LLGS
» -9-
-ir13-
*-*'« 80LT
MOLES
» SMELL
IT PLATE
NAME PLATE
1 CLEANOUT
(SEE PAR i
DRAIN-LINE '!
r-miMcrTioM
NL VSLtH
«cr
n r\t/AT' ON
OETAIL Zf WALKWAY
BRACKET uUGS
-------
» I
5.2-4
3" FRP FLANGED NCCILE
COMICALLY GUSSETTED
Figure 5.2.2
ZINC PLATED TIE or*
3" FKP FLANGED NOZZLE
3" FRP FLANGED NOZZLE
COMICALLY GUSSETTED < SIPHON)
24" TOP HINGED MANWAY
W/COVCT
HOLD DOWN CLAMP
24" StOC FLAMQED MAMWAY W/COVER
24* MCDPRENC OA9CT
7/«" i 4" LO. ST. STL. 10LTS, NUTS,
WASHEKS
24" TOP HINGED MANWtt W/COVER
HOLD DOWN CLAMP
PLAN VIEW
I
\
t
30
2^.4^"
.0"
' t
r~ "*^N
,.0. f*
.325-
i n
.375-
.450"
[ t Br__ii-r
0.250" SHELL THICKNESS
FOR REMAINDER INGJJOING OlSH
*-* PROFILE
1 1
i \
S'-O"
4-
*J
af-or
IT ^x"~ 3" ^^ FLANGED NOZZLE
ll-r^ CONICALLY GUSSETTED (SPHON )
2<" «O* n AkiArn UAMIMAV w^rv« ~
-------
I I
5.2-5
Figure 5.2.3
STEEL ATMOSPHERIC VENT
29'-2"
ir-2"
1 -
2" Of HIGH DENSITY RUBBER
INSULATION TO BE APPLIED
TO TANK TOP IN FIELD
24" TOP HINGED MJ/fWAY W/COVER
16* * 20" GASKETTED DUAL OTTOUT
EMERGENCY VENT IN MANWAY
HOLD DOWN CLAMP
PtAN VIEW
TANK WALLS I 8 - 14 GAUGE A3I STEEL !
TANK TO BE PAINTED WHITE TO REFLECT
MEAT
PROFILE
8 GAUGE STEEL
3" FLANGED NOZZLE
TANK CLEANOUT
16" i 20" IN SWING OUT FLANGED MANWAY COVER W/I6"«20"
NEOPRENE GASKET, 7/8" 26 ST. BOLTS, N'JTS ft WASHERS
-------
t
k
5.2-6
TABLE 5.2.1
Gallon Capacity Per Foot of Length
Diameter
(Inches)
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
U.S. Gallons
(1-Foot Lenath)
23.50
25.50
27.56
29.74
31.99
34.31
36.72
39.21
41 .78
4- . 4?
47.16
49.98
52.88
55.86
58.92
62.06
65.28
68.58
71.97
75.44
78.99
82.62
86.33
90.13
94.00
97.96
102.00
Diameter
(Inches)
65
66
67
68
69
70
71
72
73
-£
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
U.S. Gallons
(1-Foot Length)
172.38
177.72
183.15
188.66
194.25
199.92
205.67
211 .51
217.42
???. 42
229.50
235.56
241.90
248.23
254.63
261.12
267.69
274.34
281.07
287.88
294.78
301.76
308.81
315.95
323.18
330.48
337.86
Diameter
(Inches)
105
105
107
108
109
no -
in
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
U.S. Gallons
(1-Foot Lenath i
449.82
458. 2H
467.70
475.89
485.00
493.7i)
502.70"
511.90
521.40
53n. 2&
540.00
549.50
558.51
568.00
577.80
587.52
597.70
607.27
617.26
627.00
638.20
647.74
658.60
668.47
678.95
690.30
700.17
-------
i !
I I
5.2-7
TABLE 15.2.1 (continued)
Ga_T!on Capacity Per Foot of Lenqth
Diameter
(Inches)
51
52
53
54
55
56
57
58
59
60
61
62
63
64
U.S. Gallons
(1-Foot Lenqth)
106.12
110.32
114.61
118.97
123.42
127.95
132.56
137.25
142.02
146.88
151.82
156.83
IS^QS
167.12
Diameter
(Inches)
92
93
94
95
96
97
98
99
100
101
102
103
1Q4
Source:
Note:
Thismaterial
Laboratories,
Flammable and
Laboratories,
Laboratories,
60062.
U.S. Gallons
(1-Foot LenqtM
710.90
721.71
732.60
743.58
754.64
765.78
776.99
788.30;
799.68"
on .14
822.69
834.32
846.03
is based on and taken, with permission, from Underwriter
Inc. Standard for Safety for Steel Underground Tanks fo
Combustible Liquids, UL 58, copyright 1976 (by Underwriter
Inc.). Copies of which may be purchased from Underwirter
Inc., Publications Stock 333, Phagsten Road, Northbrook, IL
U.S. Gallons
fl-Foot Lenath)
345.33
352.88
360.51
368.22
376.01
383.89
391.84
399.88
408.00
416.00
424.48
433.10
441.80
Diameter
( Inches )
132
133
134
135
136
137
138
139
140
141
142
143
144
UL shall not be responsible to anyone for the use of or reliance upon a U
Standard by anyone. UL shall not incur any obligation or liability fo
damages, including consequential damages, arisinq out of or in connectioi
with the use, interpretation of, or reliance upon a UL Standard.
-------
I I
5.2-8
Reconstructed shop-welded tanks should be accompanied by a detailed
specifications sheet (such a sheet is generally provided by the manufacturer),
which describes not only all tank dimensions and the capacity, but any other
unique design features of the tank as well. Maximum and nominal capacities
should be delineated, especially for cone or rounded top tanks, or any other
type of tank where actual liauid storage capacity does not necessarily
correspond to the total tank volume.
Field-welded tanks are built to specification on-site. Dimensions of the
tank are usually determined by calculations which take into account the
required volume of storaae capacity in relation to the available area for the
tank. Calculated dimensions, however, may not represent actual fijal
field-constructed dimensions of the tank, due to factors which may include:
variations in design or construction techniques, irregular welding of seems
and other variables in field fabrication of tanks. All field welded tanks
should be "strapped," or accurately field measured, following construction, to
determine the actual final dimensions and capacity (nominal and maximum) of
the tank. Strapped measurements can then be compared to design specifications
to determine if sizable changes in the dimenstions of the tank are present
following field fabrication. Wherever possible, field-welded tanks should be
described using dimensions and capacities determined by field measurement
following construction.
Details concerning the wall thickness of aboveground steel tanks should
be provided to confirm that the tank design corresponds to the recommendations
for minimum wall thickness set by the Underwriters Laboratory. These
recommendations can be found in Table 5.2.2.
Minimum wall thickness for steel or other metallic vertical tanks is
generally set at 3/16 Inch, although 1/4.Inch is usually more desirable. It
is also recommended that the length of a horizontal tank does not exceed six
times its diameter.
-------
5.2-9
TABLE 5.2.2
VERTICAL STEEL TANK MINIMUM WALL THICKNESSES1
Tank Diameter Thickness
f Feet (Inches)
Smaller Than 50 3/16
50 to 120, Exclusive 1/4
120 to 200, Inclusive 5/16
Over 200 3/8
* Exclusive of any corrosion
allowance or variations in
liouid density of tank contents.
Source: API, 1978.
HORIZONTAL STEEL TANK MINIMUM WALL THICKNESSES**
Capacity Tank Diameter Thickness
'U.S. Gallons) (Inches) (Inches)
550 or Less 48 12 gauge (0.105)
551 to 1,100 64 10 gauqe (0.135)
1,101 to 9,000 76 7 gauge (0.179)
9,001 to 35,000 144 1/4
35,001 to 50,000 144 3/8
** Exclusive of any corrosive allowance or
variations in liquid density of tank contents.
Source: Underwriters Laboratory, Inc., 1972.
-------
I i
5.2-10
Thickness may also be variable with height along the sides of a vertical
tank, with the lower cross sections requiring greater thickness than the
upper. This approach to design is referred to as graduated wall thickness,
and is frequently employed in shop-fabricated, reinforced plastic tanks.
Table 5.2.3 outlines recormended minimum thicknesses for graduated wall,
reinforced plastic tanks. A safety factor of 10 is built into these
recommendations.
It should be noted that EPA, in the proposed regulations (264.191),
requires a "qualified reaistered professional engineer" to assess and certify
the structural integrity of each tank system in lieu of requiring a minimum
wall thickness. EPA will, however, be more likely to approve tank systems
which adhere to nationally accepted design standards such as API, UL, and
ANSI. A nonspecification tank system would require a demonstration by the
qualified engineer thai the thickness, or other structural aspect, was in
accordance with sound enaineerinq principals.
5.2.2.3 Underground Tanks. Underground tanks (steel or FRP tanks) are
usually shop-welded tanks built to a variety of predetermined capacities and
dimensions, although they can also be made to order to fit customer
specifications. The manufacturer should provide detailed drawings and
specification sheets for each tank. Specification sheets and drawings can be
used by the customer to spot check the dimensions of the tank to eliminate
discrepancies or questions concernina the actual tank size and capacity prior
to emplacement of the tank. A detailed specification sheet in addition to
scale drawings, should be provided by the applicant to meet the regulatory
citation of $270.16(b).
In particular, detailed dimensions and drawings should be provided for
large FRP tanks, which may be irregularly shaped and/or ribbed and difficult
to accurately describe without a scale drawing.
-------
i i
CD
trt
*5
UJ
aa
O
o
£
X
o c
«£
rsj x
^v O
«
sO s£ sO sO sO sOsOsO
-------
5.2-12
In addition, the manufacturer may also supply a gauge table for the tank
indicating capacity per foot of length (or height) for a specific tank
diameter. Field testing for FRP tanks following emplacement to confirm the
gauge table is recomended, since large FRP tanks are not rigid and may
"slump," or distend, once t^e tank installation is complete. Slumpina may
result in uneven distribution of tank volume, producing a discrepancy in the
height-to-volume ratio specified in the gauge table.
5.2.3 Major Issues
1. Are all dimensions of the tank(s) and related appurtenances clearly
indicated and/or displayed in the diaqrams? "- _;
2. Is the capacity of the tank(s) clearly indicated (nominal and/or
maximum caoacity)?
-------
t I
I I
5.3-1
5.3 DESCRIPTION OF FEED SYSTEMS, SAFETY CUTOFF, BYPASS SYSTEMS AND PRESSURE
CONTROLS (e.g. VENTS)
5.3.1 Regulatory Citations
A description of the equipment associated with the transfer of material
to storage tanks at the facility must be included with Part B of the permit
application and include tank venting capabilities and product spillage and
overfill protection devices as specified in:
Section 270.16(c) description of feed systems, safety- cutoff, -bypass
systems and pressure controls (e.g. vents.)
Part 264 of the regulations does not specify any regulatory standards
pertaining to this
5.3.2 Guidance to Achieve the Standard.
5.3.2.1 General
The intent of this requirement is to provide enough information about
equipment associated with the transfer of material into the tank and the
venting of vapors from the tank to allow evaluation of the capability of the
system in question to meet construction guidelines and standards designed to
prevent:
0 Explosion or Implosion of tanks
0 Fire
0 Emission of hazardous vapors
0 Spillage of hazardous material due to overfilling of vessels or
drainage from product transfer hoses.
-------
I I
5.3-2
All information required to make such an evaluation should be available
from the tank manufacturer and should include a description of the following
items.
5.3.2(2) Feed System. Many spills occur at storage tank facilities
during transfer of material due to overfilling of the tank, forcing of product
out of vent lines or drainage of product remaining in the delivery tube during
disconnection procedures. In underground tanks, the fill pipe may actually
have ruptured below the soil surface due to improper support and vibration
resulting in undetected discharge of material directly into the surrounding
soil. Use of proper equipment and practices can prevent transfer spills'T.of
this nature. Proper equipment to prevent overfilling of vessels consists of
instrumentation designed to continuously monitor the liquid level in the tank
and trigger an alarm system and automatic shutoff/bypass when a condition of
"high level" is reached.
5.3.2.(2)(a) Level Sensors
Liquid level sensors may fall into one of a number of classifications and
can be described by one of the following terms:
0 Float-actuated devices
0 Displacer devices
0 Hydrostatic head sensors
0 Capacitance sensors
0 Thermal conductivity sensors
0 Ultrasonic devices
0 Optical devices
The following description of level sensors will aid 1n the description of
the systems employed at the facility.
-------
5.3-3
Float-Actuated Devices. Float-actuated devices are characterized by a
buoyant member which floats at the surface of the liquid. Float-actuated
devices may be classified on the basis of the method used to couple the float
motion .to the indicating system. Examples of classifications used in
underground tanks include tape float gauges and float vent valves.
Float-actuated level sensors used in aboveground tanks include chain or tape
float gauges, lever and shaft float gauges and magnetically coupled floats.
Float-actuated devices are made of a variety of materials, including
aluminum, stainless steel and coated steel, depending upon the application.
They may be used in conjunction with pneumatic or electronic devices--to-
operate valves, pumps, remote alarms or automatic shut-off systems.
Displacer Systems. Displacer-actuated devices, commonly used in above-
ground tanks, use the buoyant fcrce of a partially submerged displacer as a
measure of liquid level. Vertical motion of the displacer is usually
restrained by some elastic member whose motion or distortion is directly
proportional to the buoyant force, and therefore to the level of the liquid.
The range is limited to the length of the displacer. The coupling of float
motion to the indicating mechanism is usually accomplished through the use of
some type of pack less mechanism, which frequently also constitutes the elastic
restraining member. Accurate level measurement with displacement devices
depends upon accurate knowledge of liquid and vapor densities. Displacer
devices can be used in top cage mountings, or side mountings in vented
(atmospheric), pressurized, or evacuated (vacuum) tanks.
Hydrostatic Head (Pressure Devices). A variety of devices commonly used
in aboveground tanks monitor liquid level by measuring hyddrostatic head. Use
of hydrostatic head measurement as an indicator of liquid level requires an
accurate knowledge of the densities of both the liquid and vapor-air mixture
inside the tank. Standard pressure or differential pressure measurement is
the method most commonly used in these systems.
-------
5.3-4
Capacitance Sensors. Devices that operate based on the electrical
conductivity of fluids may be used to monitor liquid level. A typical device
consists of a rod electrode positioned vertically in a vessel, the other
electrode usually being the metallic tank wall. The electrical capacitance
between the electrodes is a measure of the heioht of the interface along the
rod electrode. The rod is usually electrically insulated from the liquid in
the tank by a coating of plastic.
Capacitance devices are suitable for use with a wide range of liquids,
including the following: Petroleum products, such as gasoline, diesel fuel,
jet fuel and no 6. fuel oil; acids; alkalis; solvents; and-other hazardous
t, -
liquids. They may be used in conjunction with electronic controls to operate
pumps, valves, alarms or other external control systems.
Therrnal Conductivity Senso"S. Devices which operate on the principle of
thermal conductivity of fluids may be used to monitor liquid level. A typical
conductivity of fluids may be used to monitor liquid leve. A typical device
consists of two temperature-sensitive probes connected in a Wheatstone bridge
(a type of electrical circuit configuration). When the probes are in air or
gas, a maximum temperature differential exists between the active and
reference sensors, which results in a qreat imbalance in the bridge circuit
and a correspondingly high bridge voltage. When the probes are submerged in a
liquid, the temperature between the sensors is equalized and the bridge is
brought more nearly into balance. The probes may be installed through the
side wall of a tank or pipe, or assembled together on a self-supporting mount
and suspended through a top connection on the tank.
Thermal conductivity devices may be used to control level with great
accuracy. They may be used with any liquid regardless of viscosity or
density. They may also be used with immiscible liquids and slurries and in
conjunction with electronic controls to operate pumps, valves, alarms or other
external control systems.
-------
ft I
i I
5.3-5
Ultrasonic Sensors. Devices which operate on the principle of sound-wave
propagation in fluids also may be used to monitor liquid level. These devices
use a piezoelectric transmitter and receiver, separated by a short gap. When
the gap is filled with liquid, ultrasonic energy is transmitted across the qap
to a receiving element thereby indicating the liquid level. These devices may
be used in conjunction with electronic controls to operate pumps, valves,
alarms or other external control systems.
Another sonic technique used for level measurement is a sonar device. A
pulsed sound wave, generated by a transmitting element, is reflected from the
interface between the liquid and the vapor-gas mixture and'.returned to the
receiver element. The level is measured in terms of the time required for the
sound pulse to travel from the transmitter to the vapor/liquid interface and
return.
Optical Sensor. Devices which operate on the principle of light beam
refraction in fluids may be used to monitor liquid level. An optical liquid
level monitoring system consists of a sensor and an electronic control
device. A specific electronic signal is generated and aimed at the tank
mounted sensors. The sensors convert the electronic signal to a light pulse.
This light pulse is transmitted into the tank by fiber optics, through a
prism and out again via fiber optics. The light pulse is then converted to a
specific electronic signal to indicate the liauid level., A distinct advantage
of this type of system is that it is self-checking. Any interruption will
sound the alarm, so if equipment is damaged or malfunctions the operator is
alerted.
5.3.2(2)(b) Alarm System
The liqud level sensor should be tied Into an alarm system to notify 4
operators of a high level condition. The alarm system may be either visual or
audible, or a combination of the two. An audible alarm 1s generally
,g "-«f
-------
I I
I k
5.3-6
5.3.2(2)(c) Automatic Shutdown or Bypass Systems
In addition to interfacing with an alarm system, the level sensing
devices should be directly connected to an automatic shut-off control or
bypass system. These control systems are designed to receive a signal from
the level sensina device at a preset high level and automatically transmit a
message either to the tank loading pump to deactivate, or to a control system
equipped with various flow control valves and pumps to divert flow to another
storage tank. For aboveground tanks, an emergency overflow system may also be
available for manual operation should the automatic control system
malfunction. A final overflow to the atomsphere must exist in- case the entire
system (tank and overflow tank) is filled to capacity. This overflow point
must be visible.
The description of each automatic shutdown/bypass system employed at the
facility should include the type of level sensing device and the method by
which the signal is transmitted from it to the actual shutdown/bypass
mechanism. This transmission is generally accomplished by electrical or
pneaumatic means, due to their adaptability to remote operation. However,
mechanical devices are also employed. Types of valves, pumps and overflow
vessels should be provided in detail in the facility description.
5.3.2(2)(d) Fill Pipe
The manner in which liquid is admitted to a tank can cause turbulence
which can result in foaming, release of hazardous vapors, or generation of
static charge in the fluid. This is particularly likely 1f the pipe
terminates above the liquid surface; therefore, a fill pipe entering the top
of a tank should terminate within 6 inches of the bottom of the tank.
Proper support must be provided to prevent vibration which could lead to
breakage of the fill pipe, resulting in direct discharge of material to the
soil, »!"-- " jrpose of having it extend to within 6 inches of the bottom.
-------
5.3-7
Connections for all tank openings, including the fill pipe, should be
liquid-tight, properly identified and closed when not in use. Openings
designed for combined fill and vapor recovery should.be protected Against
vapor release unless connection of the liquid delivery line to the fill pipe
simultaneously connects the recovery line. A number of viWtftlons of liquid
delivery/vapor recovery systems are available and description of the type
system employed in each tank is required.
Another feature commonly Included in the fill line of a tank or the
discharge pipe of a pump is a check valve system to prevent reversal of flow.
Check valves are available in three basic designs: swing check valves; l>ft-
check valves; and tilting-disk check valves. They are available in a wide
variety of sizes and materials of construction to suit most applications.
Transferring hazardous materials into storage tanks also requires the use
of tight coupling connections selected to withstand the temperature, pressure
and chemical compatibility requirements demanded of them. Couplings may be
described in terms of their method of connection and material of construction
with respect to temperature, pressure and chemcical compatibility
specifications.
The description of the fill pipe and associated check valves and
couplings should include the following items:
0 Material of construction of fill pipe.
0 Termination distance from tank bottom of fill pipe.
. _v*.
0 Method of attachment and support of fill pipe.
0 Liquid delivery/vapor recovery system.
0 Fill pipe closing apparatus. (
0 Type and location of check valves including size and material
of construction.
-------
I I
i I
5.3-8
0 Type of couplina connections including size and material
construction.
5.2.3(3) Pressure Control System (Vents)
Covered storage tanks are equipped with pressure relief mechanisms to
prevent physical damage or permanent deformation of the tank due to
exceedances of the normal operating pressure or vacuum. Addition of materials
to a tank, as well as expansion and evaporation due to thermal changes results
in "outbreathing" (pressure relief) of vapor from the tank. The required
venting capacity for a tank must surpass the sum of the venting requirements
for addition of product into the tank and expansion due to thermal effects.
Inbreathing (vacuum relief) occurs when product is removed from a tank or when
the gas volume decreases due to thermal effects. Exposure to fire can result
in rapid pressure increases making additional emergency venting capabilities
necessary.
Specific construction specifications designed to meetin inbreathing and
outbreathing requirements are dependent upon a number of operating variables
which must be included in the description of The Pressure Control System
called for in 40 CFR 270.16(c). A list of items to be addressed in the
description is provided below, followed by a brief dscussion of each.
? -r ; ~*iJi» -
1) Flash point and other relevant characteristics of the liquid or
solid waste to be stored.
<*&
2) Design pressure of the tank if applicable.
3) Vent size and capacity ..V-^->
4) Emergency venting capabilities -- .._ -%V
,j*e.-» i
5) Types of vents.
s
6) Location and arrangement of vents Including the point of
termination and piping configuration.
-------
! I
t i
5.3-9
5.3.2(3)(a) Flash Point
i_-
It is important to include the flash point of the "liquid or
to be stored in the tank to be permitted because it is A vdeter mining factor in
*>wyR. * '' *> '
several design specifications of the venting system, and as such 1s necessary
in evaluating if the proposed use for the tank is appropriate.*^ Flash point
dictates design requirements such as venting capacity, emergency venting
capacity, roof to shell construction, design pressure, etc.
5.3.2(3)(b) Design Pressure
*_
If a tank is constructed to meet design pressure specifications, the
venting capacity must be sufficient to prevent the development of pressure or
vacuum, as a result of filling, emptying or atmospheric temperature changes,
in excess of tht design pressure. Therefore, information concerning the
design pressure of the tank is critical to the assessment of the pressure
control mechanisms.
5.3.2(3)(c) Vent Size (Capacity)
Venting capacity must be sufficient to accomodate outbreaking due to
maximum product movement into a tank, the resultlnq evaporation and thermal
. -~,,- - - - ' je7*ji*»~
effects, as well as inbreathing due to maximum product movement out of a Tank
and thermal effects. Venting capacities dictated Jaythermal effects istre
"**.*..-' A'-^^-v
provided in Tables 5.3-1 and 5.3-2. Venting capacity to accomodate thermal
inbreathing that is based on overall tank capacity is provided In^iJable
* - .. j?«.. -...-v. j*ff^ -*«@3rj&.
5.3-1. Requirements for thermal outbreathlng 1s based on the flashpojntjpf
the stored material as well as the capacity of the tank. T*ble*5i1)-2;^r*ndes
"»~£9"r
additional Information incorporating tank design pressure Into the
determination of the venting capacity needed.
-------
I I
I t
5.3-10
Table 5.3-1
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-------
I I
5.3-11
Table 5.3-2
THERMAL VENTING CAPACITY^REQUIREMENTS
(Expressed in Cubic Feet of Free Air per hour
at 14.7 psi absolute *nd 60° F)
OutbreatMng
(Pressure)
Tank Capacity **
(Barrels;
6
100
500
1,000
2,000
3,000
4,000
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
60,000
70,000
80,000
90,000
100,000
120,000
140,000
160,000
180,000
**
NOTES:
) (Gallons)
2,500
4,200
21,000
42,000
84,000
126,000
168,000
210,000
420,000
630,000
840,000
1,050,000
...
...
...
...
...
---
...
_.-
...
Interpolate for
1. For tanks
Inbreathing
Vacuum
All
Stocks
60
100
500
1,000
2,000
3,000
4,000
5,000
10,000
15,000
20,000
24,000
28,000
31,000
34,000
37,000
40,000
44,000
48,000
52,000
56,000
60,000
68,000
75,000
82,000
90,000
intermediate
with a capac
Flash Point
100°F (37.8°C) or
Above
40
60
300
500
1,200
1,800
2,400
3,000
6,000
9,000
12,000
15,000
17,000
19,000
21,000
23,000
24,000
27,000
29,000
31,000
34,000
36,000
41,000
JtS.-OOO .^
50,000
...54,000
sizes
:ity of more than 2C
Flash Point
Below
100F (37.8°C)
60
100
500
1,000
2,000
3,000
4,000
5,000
10,000
15,000
20,000
24,000
28,000
31,000
34,000
37,000
40,000
44,000 ***
48,000
52,QOOj*jK§|ferr
' 56 ,UOO*^^
60,000
68,000
" 75 i99$^fttf&;
vV :'4)2|tK)0 ^^^
^^Afe-
i iTMMh*ili"friiiiiii
-iMcw in ' '^5S*JHIH(BUJ
1.000 barrels
(840,000 gal.), the requirements for the vacuum condition are
very close to the theoretically computed value fcf 2 cu.r^ft.
of air per hr. per sq. ft. of total shell j»nd roof.jirta.
2. For tanks with * caoacltv nf !- *w ««aftftft Jki^iUi-
-------
I I
I I
5.3-12
Table 5.3-2
THERMAL VENTING CAPACITY REQUIREMENTS
NOTES: (Continued)
3. For stocks with a flash point of 100°F (37.8°C) or above, the
outbreathing requirement has been assumed at 60 percent of the
inbreathing capacity requirement. The tank roof and shell ,tem-
peratures cannot rise as rapidly under any condi-tlon as they .xran
drop, such as during a sudden cold rain.
4. For stocks with a flash point below 100°F (37.8°C), the thermal
pressure-venting requirements has been assumed equal to the vacuum
requirement in order to allow for vaporization at the liquid
surface and for the higher specific gravity of the tank vapors.
(From API Standard No. 2000, 1982, "Venting Atmospheric and Low Pressure
Storage Tanks.")
-------
t I
I I
5.3-13
Venting capacity required to accomodate the maximum material flow into a
tank and the resulting evaporation should be the equivalent of*600t:u. ft. of
free air/hr/100 barrels for each hour at the maximum filling rate for liquids
with flash points of 100°F or above. If the flashpoint is below 100°F, 1200
cu. ft. of free air/hr/100 barrels is necessary for each hour at fliaximum
fill ing rate.
For maximum withdrawal of material from a tank, the venting capacity
requirement should be equivalent to 560 cu. ft. of free air/hr/100 barrels for
each hour at the maximum emptying rate.
*_ -
Description of the size and capacity of vents should include information
justifying their adeaucy including tank capacity, maximum inflow and outflow
rates and, as discussed earilier, design pressure and material flash point. *
5.3.2(4) Emergency Venting Capabilities
In cases of excessive heat exposure, such as fire, the venting capacity
requirement may exceed that required for maximum addition of material and
normal thermal effects. If emergency venting capacity is provided, your
description should include the size, capacity and type of venting equipment
employed.
.«,«. «^rs
?*.'**£'
In some cases tanks are equipped with a weak roof-to-shell attachment in
which the welds at the point of connection between,She^roof and .sHtfJf^hll
fail prior to any other joint (maximum 3/16-inch single pellet weld). This
feature provides safe pressure relief 1n the tventrfrttat the to
capacity of the system is exceeded. Tanks built to these specif 1catons«jped
not contain any additional emergency venting mechanisms.
-------
I I
5.4-1
5.4 Diagram of Piping, Instrumentation, and Process Flow
5.4.1 Regulatory Citation
The owner or operator of a tani
with a diagram(s) of the piping,
required in:
"§270.16(d), [provide] a descrip
process flow for each tank system
Part 264 of the hazardous waste stor<
regulatory standards with which tank s
5.4.1.1 Guidance to Acmeve the Dart
The intent of the Section 270.'
tank facility is designed in a ma
released waste to the environment. Sij
minimize piping lengths,
joints, and couplings
system must provide the permit writer
instrumentation, and process flow, as
ion of piping, instrumentation, and
n
ge tank regulations does not specify any
ystem equipment diagrams must comply.
264 Standard
6(d) requirement is to ensure that each
ner that minimizes the possibility of
ch a design would, for example:
crossovers over other equipment,
have adequate instrumentation such as level alarms, "f low* "
meters, shut off valves, etc., to monitor and react to changing
liquid and pressures levels
have process flows that separate incompatible materials, con-
tain appropriate capacity and venting, have adequate line
cleanout capabilities, and minimize ,the Ofted
Diagramming of a tank system's piping, instrumentation, and process flow
can range from a detailed schematic drawing of allsiiselevtnt «||ink.^|ystem
components to a complex blueprint, drawn to scale. Relevant tank system
components that should be shown on a diagram are:
-------
5.4-2
o fill lines (inlets),
o draw-off lines (outlets)
o piping, including directional changes
o pumps - , f~~,-
. «<-
o flow meters
o level alarms
o valves
o vents
o leak detection devices
o manholes and other openings
o drainage
Blowups of complicated portions of a diagram to emphasize relevant features
may be useful (see Figure 5.4-1).
Accompanying documentation with a tank system diagram might explain
briefly why particular instrumentation was selected. Documentation might also
contain mass balance equations and a description of any complicated process
flow aspects, including the cleaning of a tank system if new wastes that may
be incompatible are introduced. Figures 5.4-2 and 5.4-3 contain examples of
schematic diagrams for underground and aboveground tank facilities,
respectively.
-------
5.4-3
Figure 5.4-1
At Liquid Withdrawal Location:
Pipinq Details for Suction or Submerged Pumps
IH COM WITH »»IO»
"»f ce» WITH into*
«CT »»l»t WIT*
'until urn*
..- ,
t '«* ' V .'' >'-I
H-.'« ."'»r'«'-.'*.«1 './/''"'.'I ' f->:.'c.».'':if".'-""»:.. ".']
./^.v-v/i-.c-i;- ;'.*.: '.-;...;.-jlv.';.;i!Visi.'«-
'--'- ' '- > ^ 'i^ '.-.' , <,!°-. ^VJ'. ' ^' ? --.'^ t--N
u>0ft ruu* C»tci
UUDI
\ *>e«on ««IM ioot wm
V-IOIT >m *n«if mo*
UCTIOH
UIMMOCD
-------
5.4-4
Figure 5.4-2
Elements of an Underground Tank Facility
t) OVERFILL PREVENTION DEVICE
TANK TRUCK
VAPOR RECOVERY LINE
_.
©
FLOAT VENT VALVE
OBSERVATION
WELL f
CORROSION-RESISTANT
STORAGE TANK
EXCAVATION
CAP
OBSERVATION
WELL
ORSANDFILL
EXCAVATION WALLS AND
FLOORS OF IMPERVIOUS
MATERIAL
AUTOMATIC
?l SMUTOFF
VALVE
0
DELIVERY LINE
LEAK DETECTOR
\
SUBMERGED PUMPASSEMBLY
Well-designed underground storage systems usually contain the following:
1)corrosion-resistant tank; 2) striker plate under tank fill line;
3) submerged pump with leak detector on product delivery line; 4) float
vent valve in tank vent line; 5) excavation walls and floor of impervious
material; 6) asphalt or concrete excavation cap; 7) automatic shutoff
valve; 8) overfill prevention device at fill line on tank truck; 9) vapor
recovery in tank truck during filling operation; 10) observation wells
located inside excavation boundaries; 11) pea gravel or sand fill for
excavation.
-------
5.4-5
Figure 5.4-3
Aboveground Tank System Connections
Siik MCV. shewing ihc fill connection, pipe
nt uo'L: mnnrciii>r. drjin tonncciMr. dram
v sump jnd ijil.
b) PerNpciiivc drdwinj: shdumj: the fill connection, pipe line outlet connec-
tion, drjm connection, overflow connection, and vent connection.
Source: API RP 12R1, Recommended Practice for Setting, Connecting,
Maintenance and Operation of Lease Tanks, 1981.
-------
5.5-1
5.5 EXTERNAL CORROSION PROTECTION
5.5.1 Regulatory Citation
Corrosion inforTatton rec^ired by facil;t*es that store or t"eat
waste in tanks must be included in Part B of the permit application, as
specified in:
"6270.16(e) - Description of materials and equipment used to
provide external cor-osion protection, as required under
264.191(c)."
Part 264.191(c) of the regulations specifies the tank design standards and
general operating reauiregents far compliance.
5.5.1.1 Citation: Corrosion Potential Assessment
on
For a tank system with metal components in contact with soil, Secti
264.191(c)(l) requires that the registered professional engineer obtain an
assessment by a corrosion expert of the corrosion potential of the soil
environment surrounding the system. This assessment must address:
"Factors affecting the potential for corrosion, including but not limited
to:
(i) Soil moisture content;
(ii) Soil oH;
(iii) Soil sulfides level;
(iv) Soil resistivity;
(v) Structure to soil potential;
(vi) Influence of nearby underground metal structures (e.g.,
(vii) Existence of stray electric current;
(viii) Existing corrosion-protection measures (i.e., coatings,
cathodic protection)."
-------
5.5-2
5.5.1.1.1 Guidance to Achieve the Part 264 Standard
Accurate information must be obtained on the environment surrounding a
metal tank system in contact with soil, because such a tank system may be
highly susceptible to corrosion. A "corrosion expert" will need to be
consulted to assess the corrosion potential, as quantitatively as possible, of
a particular environment. EPA expects this corrosion expert to be a person
who, by reason of his/her knowledge of the physical sciences and the
principles of engineering and mathematics, acquired by a professional
education and related practical experiences, is qualified to engage in
corrosion control for metal tanks and/or piping in contact with soil. The
National Association of Corrosion Engineers (NACE) can provide a listing of
corrosion experts Qualified in this subspecialty. For information on such
individuals, the perrrnt apnl^cant can contact NACE at the following address:
Manager, Accred^ tation Programs
National Association of Corrosion Engineers
Post Office Box 218340
Houston, TX 77218
Registered professional engineers with appropriate cathodic protection
experience on buried or submerged metal tank systems may also perform the
corrosion potential assessment. The create** the accuracy of a corrosion
potential assessment, the more appropriate a cathodic protection system desion
will be.
Corrosive deterioration of tank material may be either general or
localized. General corrosion appears as a uniform loss of surface material,
whereas localized corrosion results in a non-uniform loss of material from the
corroded structure. Table 5.5-1 lists several common forms of localized
corrosion. Table 5.5-2 lists environments that may cause corrosion. Figures
5.5-1 and 5.5-2 diagram some of the major corrosion-inducing factors.
-------
5.5-3
Table 5.5-1
Common Forms of Localized Corrosion
Type
Descr ipt i on
Pitting Corrosion
Formation of shallow depressions or deep pits
(cavities of small diameter).
Stress Corrosion
Cracking
Corrosion accelerated by residual stresses re-
sulting from fabrication operations or uneaua-1
heating and cooling of structure.
Contact or C>-e
Corrosion
curs at, *_ne roint of contact or crev'c
e betwee
a metal and a non-metal or between two metals
Intergranular
Corrosion
Selective corrosion at the grain boundaries
(microscopic) of a metal or alloy.
-------
5.5-4
Table 5.5-2
Environments that Can Cause Corrosion
Vaterial
Env ironment
Aluminum
Water and steam; NaCl, including sea
atmospheres and waters; air; water vapor
Copper
Tropical atmospheres; mercury; HqNC
bromides; ammonia; ammoniated
and ?te3~: H..SO.; caustics
Austenitic stainless steels
Chlorides, including FeCl-, FeCl,,
NaCl; sea environments; H~S04;
Fluorides; condensing steam from chlor-
ide waters
Ferritic stainless steels
Chloride, including NaCl; fluorides;
bromides; iodides; caustics; nitrates;
wate"; steam
Carbon and low alloy steels
HC1; caustics; nitrates; HN03; HCN;
molten zinc and Na-Pb alloys; H S;
; H$0; seawater
High strength alloy steels Sea and industrial environments
(yield strength 200 psi plus)
-------
= c_ c;
Table 5.5-2 (continued)
Environments that Can Cause Corrosion
Env ironment
Maqnes ium
Lead
Nickel
Monel
Inconel
Ti tan ium
Nad, including sea environments; water
and steam; caustics; N?0^; rural and
coastal atmosphere; distilled water
Lead acetate solutions
Bromides; caustics; H9SO^
Fused caustic soda; hydrochloric and
hydrofluoric acids
Caustics soda solutions; high purity
water with few ppm oxygen
Sea environment; NaCl in environments
288°C (550°F); mercury; molten cadmiun;
silver and AqCl; methanols with halides;
fuming red HNO^; N?0.; chlorinated
or fluorinated hydrocarbons
Source: Pludek, 1977
-------
5.5-6
Figure 5.5-1
Some Corrosion Mechanisms at an Underground Steel Tank
Snail differences in electric (io^ic) potential can cause serious
corrosion of underground steel tanl-s and pipes. Such differences can be
created when there is a presence of dissimilar soils or bacterial
activity, as shown in figures below. The curled arrows (x"~^--*) show the
flow direction of electric current in these figures.
r*- 6L08 Of CL*T on Si DC
Qf TANH.HESULTJNGIN
(o) Dusimitor Soilj Voriotions in joil type 0' JoH propertus »uc" os ocifli'y
or rtsfivily cori Icod to corrosion in an underground (IMl Structure .
PAVEMENT
HOMOGENOUS BACKFILL
STEEL TANK
AEROBIC MECON
CATHODE
INOCO**OSION)
KECK)*
fTM iACTEWlAL ACTtVTTt
(COMtOSiO*
(-1
-------
5.5-7
Figure 5.5-?
More Corrosion Mechanisms at an Underground Steel Tank
Othe»" ite^s w^ich can promote corrosion at underground steel tanks
include the presence of dissimilar metals or moisture, as shown in the
figures below. The curled arrows (*-\-*) show the flow direction of elec-
tric current in these figures.
LAVEMENT
HOMOGENOUS BACKFILL
(o)
M>tols Eipoturt 10 dmimilor m»tol», »ucr-> os conrv«ct»on of o
tank with mttol pip* vith diff*r«ni prop*rti«t. or burial of a r>«» tank
n«or an oW tank, con Miflfl lo corrotion
PAVEMENT
HOWOOENOUS BACKFILL
STEEL TANK
CATMOCNC MC6KM
(NOCOMMOSION)
(4)
ANODIC RECK)*
ICOAftOSIOM)
Mou'ur* Th« or»»»rx« of mOillUTI COB
-------
5.5-8
Each of the factors listed in Section 264.191(c)0} and shown in Figures
5.5-1 and 5.5-2 affects the corrosion potential of the environment surrounding
a tank system. The following discussion provides an overview on how these
factors affect the likelihood for corrosion and discusses how the
environmental data obtained are interpreted by a corrosion exoert. In this
manner, the relative influence on tank system corrosion from each of the
factors, and their combinations, may be determined. It is important for an
assessor to examine not only current environmental conditions surroundina a
tank system, but also to look at how these conditions seem to change ove"
time. For example, soil moisture level may fluctuate seasonally. Only an
experienced corrosion expert is qualified to utilize best engineering
judgement to assess the surrounding environment and the cathodic protection
needs of a tank system.
t - The presence of moisture or water in soil acts to
reduce soil resistivity, thereby increasing the probability and rate of cor-
rosion in any portion of a tank system in contact with the soil. Trapped
water near a tank system can become anaerobic and cause what is known as
bacterial corrosion. A corrosion expert can identify an instance of bacterial
corrosion by its musty smell, the presence of hydrogen sulfide, and other
identifying characteristics (see soil sulfides, below).
Water can become trapped near a tank system from man-made or natural
phenomena. For example, improper installation practices can cause water to
accumulate alongside a tank, e.g., when the-e are voids in the backfill. A
more complicated instance of soil moisture level affecting corrosion occurs
when highly compacted road bases near a tank system have impermeable,
compacted soil underneath the roads. This scenario can alter the ground water
flow conditions below the tank system because water will no longer flow
through the surrounding soil. Chemical salts may then accumulate near the tank
system, changing the chemistry and pH of the soil and potentially enhancing
corrosion (see soil pH, below).
-------
5.5-9
The introduction of irrigation or natural phenomena, such as earthauakes
and seasonal soil moisture changes, can also change the flow and/or
directional characteristics of the ground water underlying a tank system. A
corrosion expert must use past experience with other tank systems to recognize
and assess Qualitatively the effects of soil moisture levels on present a^d
future corrosion rates.
Soil pH -- Soil p^, a measjre of the hydrogen ion content of soil, is an
indicator of soil chemical characteristics. A corrosion expert must use the
pH information, in conjunction with other data on soil conditions such as
sulfide and chloride levels and moisture content, to assess the chemical
corrosion potential of a particular soil environment. Soil samples should be
taken as near to the bottom of a tank as possible. The pH is then measured
with a simple metering device.
Low soil pH indirectly 'ndicates elevated soil chloride content, a
frequent cause of chemical corrosion. Additionally, when soil pH does not
fall into the neutral range of approximately 6.2 - 8.7, soils may have unusual
chemical characteristics that can cause corrosion. The presence of oxidizing
agents in soil, such as nitrates, will induce corrosion. In the presence of a
non-neutral soil pH, further chemical analyses may be necessary to assess the-
corrosion potential of the unusual soil environment. Low soil pH in sandy
conditions, however, mgy simply indicate the presence of rainwater during the
time of the pH test. High soil pH, in general, indicates a less corrosive
environment.
Soil Sulfides Level -- Sulfide levels can indicate the potential for
bacterial corrosion. While the bacteria do not directly affect corrosion,
their metabolism converts soluble sulfates in soil to sulfides, under
anaerobic conditions. These sulfides can form acids that may attack tank
system metal, causing corrosion. Soils with sulfide (or chloride) levels OM
approximately 300 mg/1 are considered highly corrosive. Chloride often
accumulates in soil from road salting in winter. Soil sulfide or chloride
levels and soil pH, in combination, is the second most important factor
-------
5.5-10
for evaluating the corrosion potential of a given environment, following
soil resistivity.
Soil Resistivity -- Soil resistivity, the ability of soil to resist
the flow of electricity, is the most important factor in assessing
corrosion potential and in designing adeauate cathodic protection. A
corrosion e*oert uses resistivity as a gage for predicting the aalvanic
and st^ay electric current corrosion rates. Galvanic corrosion occurs
when two dissimilar metal objects are placed in direct or electrical
contact. Stray current corrosion results from direct electrical currents
flowing through the ground fron an external power source (see stray
electric current, below). The flow of electrons durina corrositvi
processes takes place through the soil; thus, high resistivity soil
ir.pedes electron movement and slows corrosion. Without corrosion
>~, >*O*"P "*""**ri *" h £ "* ~ /* P *" *" ^ P S"1"'^ r o c * c t "' V "" *" V *" ^ a QrPa^P*" fV"o rr^^-^cinr)
rate. There is no upper li"iit on resistivity in which a tank system will
not corrode, however.
To assess corrosion potential, a corrosion expert must measure the
resistivity of the soil, probably using ASTM Method G57-78 (the Wenner
method). Soil samples should be obtained as near to tank system metal as
possible, preferably soil in contact with a tank bottom or soil along the
tank sides near the tank botto^. A corrosion expert should also try to
ascertain whether the soil environment around a tank system is
inhomogeneous with respect to resistivity. If so, additional soil samples
may have to be obtained.
Resistivity measurements reflect moisture and chemical constituent
levels in soil. The corrosion expert must use best engineering judgement
to evaluate how soil moisture, pH, and sulfide/chloride data will affect
resistivity measurements in a given soil environment over time. For
example, the corrosion expert has to estimate the magnitude of the effect
on resistivity of seasonal ground water level changes, road salt
application, road installations that affect ground water, etc. These
-------
5.5-11
estimates will be based on past experience with other similar tank systems
and analysis of local historical seasonal climatic changes.
Structure-to-Soil Potential -- Structure-to-soil potential is a
measi,""e~ent of the voltaae between a tank and the surrounding soil. le
voltage is higher in soil than in a tank, electric current will flow from
the tan'< to the soil, producing corrosion. The magnitude of the voltage
is an indirect measure of how fast corrosion is occuring.
To measure structure-to-soil potential, the corrosion expert typically
uses a cooper-coDDer sulfate electrode. A lead from a tank is connected
to a voltmeter, which is then connected to the electrode-placed on- the
soil, as close to the tank as possible. A metal tank system that is
adeauately protected from corrosion has a structure-to-soil potential less
thai : j ""!": ", r ^ * 5 "-~:at~i/'?. Vc^taces ""c^e ne-atwe th2" 2cCn
millivolts, measured using a copper-copper sulfate electrode, howeve^, can
damage tank coatings and/or affect the corrosion potentials of nearby
structures.
Influence of Nearby Underground foetal Structures -- The media between
nearby underground metal structjres and a tank system (e.g., water and/or
soil salts) can provide the necessary electrical connection so that
galvanic corrosion can occur. In other words, the underground media
complete the anode-cathode circuits of dissimilar rretals that enable
corrosion to occur. A corrosion expert can assess the extent that nearby
metal structures in contact with soil (including other tanks; new metal
tanks are anodic to older tanks) influence the corrosion potential of a
tank system, based on experience with other similar tank systems. The
distance between any nearby structures and a tank system is an important
factor in this determination. A separation of 12 inches between nearby
buried metal structures is generally the minimum acceptable distance. The
overseer of tank installation should ensure that new metal tanks installed
alongside old metal tanks are adeauately separated (see Section 6.0). If
separation is not possible, nearby metal structures may have to be
electrically isolated.
-------
5.5-12
Nearby metal structures can also be indirectly connected electrically
to a tank system, via facility electrical and/or water system connections,
for example. This situation should be prevented using electrical
isolation devices (e.g., insulated bushings, etc.).
If a nearby underground metal structure has a cathodic protection
syste^, t^e system must be properly connected to or electrically isolated
from, the tank syste~. Otherwise, stray currents from the cathodic
protection system can cause accelerated corrosion of portions of the tank
system.
Existence of Stray Electric Current -- Stray electric -currents (DC-)
from subway, gas distribution, and any other type of direct current power
distribution system can increase the corrosion potential of a tank
s y s"- ^~. ~'" s ~ t i ^'~" ~^'- ^ "''',-,'"~ z fm t" ? ""*"'" ^ ~ _.'" c ~ ~ t ^r o j 'i h f~e
ground to the tan* system, and then back to the sources, cause stray
current corrosion.
The rate at which stray current corrosion occurs is directly related
to the intensity of the currents. These currents, if large enouah, can
even cause coatings to separate from tanks. * corrosion expert should be
able to assess the relative corrosion potential of a tank system by
determining its oroxi-nity to sources of stray current (usina maps),
evaluating the complex electrical conductance of t^e ground surrounding
the tank system, and by measuring the magnitude of the stray currents.
Existing Corrosion Protection Measures -- A corrosion expert will he
able to assess the effectiveness of existing corrosion protection measures
by examining past records for a tank system and determining the
reliability of these protective measures. The information obtained in
this assessment will be used by the corrosion expert to ascertain the
corrosion protection needs of the tank system, as required under Section
264.191(c)(2). This section (5.5) does not include corrosion control
''-Ihods based en chemical control of the environment or the use of
electrically conductive coatings.
-------
5.5-13
The corrosion protection practices using coatings, electrical
isolation, and cathodic protection are described in the National
Association of Corrosion Engineers (NACE) Standards RP-02-85 and RP-01-69,
"Recommended Practice - Control of External Corrosion on Metallic Buried,
Partially Buried, or Submerged Liauid Storage Systems" (19?5) and
"Recommended Practice - Control of External Corrosion on Underground or
Submerged Metallic Piping Systems" (1983), respectively, and API
Publication 1632, "Cathodic Protection of Underground Storaae Tanks and
Piping Systems" (1983). Coatings electrically separate tank systems fron
the surrounding ground media. Wraps perform the same function as
coatings, but wraps are not bonded to tank systems and thus r^jst be
properly installed to be effective (wrapped tanks are a forr? o-f
double-walled tanks). Electrical isolation devices (e.q., insulated
bushings, joints, and couplings) separate a tank system fron all nearby
i r, ^ £ f r»»- f~ " "" p * a 1 C. ^ *
',J > W w ' '-'' _ -^ > ' > ^ ^ ' _>U
Cathodic protection methods prevent current from leaving a tank system
through the use of either a sacrificial anode system or an impressed
current system. A sacrificial anode system causes current to flow to a
tank system from a more electrically active metal, known as a sacrificial
anode. An impressed current system employs a rectifier to oroduce a
direct current that flows from a non-corroding anode, through the ground,
to a tank system.
The corrosion expert must describe which corrosion protection methods
are employed for a particular tank system and must judge how effectively
these methods have prevented corrosion in the past. Questions that should
be answered to judge corrosion protection effectiveness include:
0 Has the tank system leaked in the past? Has the
structure-tosoil potential remained consistently at 850
millIvolts negative?
0 How complete is the coverage of a coating or wrap? Has this
coverage decreased over time from drying, cracking,
J:-..-.. j 'on? Will the coating or wrap be damaged by spills of
the tank's hazardous contents?
-------
5.5-14
0 Is the electrical isolation from nearby underground metal
structures adequate (i.e., is the tank system electrically
isolated from anchor straps, compressors, pumping stations,
other metal tanks, and at the junctions of coated and uncoated
piping, etc.)? Are the electrical isolation devices damaged in
any way?
0 HOW long has a sacrificial anode system bsen in place and have
the anodes decreased significantly in size? Is the
structure-to-soil potential greater than 1.5 volts without
cathodic protection installed, at a level that is difficult to
protect with a sacrificial anode system? Is the protective
current requirement variable, reauirinq that an impressed
current system (not a sacrificial anode system) be installed?
Is the sacrificial anode system damaged in any way?
0 How long has an impressed current system been in place and have
protective current requirements changed over time? Are there-
any trends to protective current changes (e.g., consistent
increases or cycles in protective current requirements)? Is the
st'-ucture-to-soi 1 potential greater than 100 volts without
ra^hrjH-ir c""°tection installed, at a level that is difficult to
protect with an impressed current system? Is there a
polarization decay voltage shift of at least 0.10 volts when the
rectifier is turned off or a negative voltage shift of at least
0.30 volts when the protective current is first apolied, both
measured between the structure and soil using a copper-copper
sulfate electrode (either case indicates adequate corrosion
protection)? Is the impressed current system damaged in any way?
Based on the answers to the above questions, the corrosion expert will be-
able to apply best engineering judgement to assess both Qualitatively and
quantitatively the extent to which existing corrosion protection measures
reduce a tank system's corrosion rate. The NACE and API references listed
above provide additional information on assessinq tank system corrosion
potential.
5.5.1.2 Citation: Corrosion Protection Assessment
Given information on the environment surrounding a tank system, as
obtained under Section 264.191 (c)(l}, a corrosion expert can estimate the
corrosion protection needs of the system. As required by Section
264.191(c}(2), the corrosion expert must assess:
-------
5.5-15
"The type and degree of corrosion protection needed to ensure the
integrity of the tank syste-n for its intended life, consisting of one
or more of the following:
(i) Corrosion-resistant materials of construction such as
special alloys, fiberglass reinforced plastics, etc.;
(ii) Corrosion-resistant coating (such as epoxy, fiber glass,
etc.);
(iii) Cathodic protection (i.e., impressed current or sacrificial
anocfes ) ; and
(iv) Electrical isolation devices such as insulatina joints,
flanges, etc."
5.5.1.2.1 Guidance to Achieve the Part 264 Standard
»-<^~o"*'3l r Qldi t i O
surrounding a tank system, he/she will have a good idea of the extent of the
corrosion protection measures needed to protect the system. The more
corrosion protection measures employed, the greater the degree of protection
(e.g., corrosion-resistant coating in combination with cathodic protection can
provide close to 100 percent corrosion control). The NACE and API references
cited in 5.5.1.1.1, NACE RP-02-85, RP-01-69, and AD: 1632, provide additional-
information on tank system corrosion protection needs.
The selection of corrosion protection measure (s) for a tank system must
consider environmentil conditions, waste compatibility needs, cost, and
contractor technical capabilities. This last consideration is particularly
important because even the best corrosion protection measure(s) will be
inadequate if they are improperly implemented. Poor installation of
corrosion-resistant materials of construction (denting an FRP tank or
improperly preparing a tank for coating application, as two examples),
incomplete coating application, poor electrical connections for a cathodi^
protection system, and improper electrical isolation can each adversely affect
corrosion protection. Thus, in selecting a corrosion protection design, it is
important to consider that various «-?"*--.-*ors have different levels of
experience and different areas of corrosion protection expertise.
-------
5.5-16
Corrosion-Resistant Materials of Construction -If a tank system is new,
selection of a tank system with corrosion-resistant materials of construction
may be advisable. Manufacturers can provide more information on the
corrosion-resistant characteristics of tank system materials of construction
and their compatibility with tank contents. A tank system with certain tyoes
of secondary containment, i.e., installed within a wrap or a concrete vault,
is considered corrosion-resistant if it does not contact soil or ground
water. A tank syste^ constructed on its exterior of corrosion-resistant
materials can be made so it is entirely electrically isolated from the ground
media if the system is properly constructed.
The most commonly used non-metallic corrosion-resfstant material of
construction is fiberglass-reinforced plastic (FRP). Although FRP tanks are
generally referred to as a single class, they can be fabricated from a wide
variety c* resits. ~ke se'eit'c^ of resin deoe^s ..on compatibility with t^°
material to be contained and the conditions of storage. FRP tanks can be
installed in a wide variety of soil conditions without concern for corrosion.
The primary disadvantage of the material is that FRP is somewhat more
sensitive to some installation errors than steel, because FRP is less flexible
than steel.
Corrosion-Resistant Coating -Coatings are thin (approximately 1/8 inch)
films made of natural or synthetic material, either sprayed or brushed on a
tank or piping to reduce internal/external deterioration. Linings are sheet
materials attached to the inner shell of a tank to protect against internal
chemical corrosion. Table 5.5-3 lists types of coatings/linings and the
materials with which these materials are generally incompatible. The
advantage of applying a coating and/or lining to metal tank system components
is that the tank system then combines the corrosion-resistant qualities of the
coating or lining with the structural strength of the underlying metal. Any
damage to a coating, however, can produce accelerated local corrosion on the
exterior of a metal tank system.
-------
5.5-17
Table 5.5-3
Coating/Lining vs. Chemicals
Coatina/Linina Material
Generally Incompatible With:
Alkyds
Chlorinated Rubbers
Coal Tar Epcxy
Strong mineral acids, strong alkalies,
alcohol, ketones, esters, aromatic
hydrocarbons
Organic solvents
Strc°a o^a^ic solvents V
Epoxy famine cured, polyamide Oxidizing acids (nitric acid), ketones
cured, or esters)
Oxidizing acids, strong alkalies, mineral
acids, ketones, aromatic hydrocarbons
Strona mineral acids, strong alkalies,
alcohols, ketones, aromatic hydrocarbons
Polyesters
Si 1icones
Vinyls (polyvinyl chloride-PVC) Ketones, esters, aromatic hydrocarbons
-------
5.5-18
A factory-installed coating is generally preferable to a field-installed
coating. Coating and lining manufacturers can provide information on the
corrosion-resistant characteristics of their manufactured materials. The NACE
publications listed in Section 5.5.1.1.1, RP-02-85 and RP-01-69, provide
additional information on desirable coating characteristics, and on coatira
handling, inspection, and installation techniques, as well as references on
coatings.
Cathodic Protection -Cathodic protection is the most powerful means of
corrosion protection available and it is often used in conjunction with one or
more other corrosion protection measures. As discussed in Section 5.5.1.1.1,
cathodic protection can consist of installation of a sacrificial anode system
or an impressed current system.
The galvanic caticdic protection netted employs a sacrificial anode,"such
as magnesium or zinc, in electrical contact with the metal structure to be
protected. These anodes may be buried in the ground nearby or attached to the
surface of a metal tank system. The necessary, low-level, electric current
generated is produced by corrosion of the sacrificial anode material. A
typical sacrificial anode cathodic protection system for underground tanks and
piping is illustrated in Figure 5.5-3.
A sacrificial anode system can either be purchased from a tank
manufacturer with the anodes already attached to a tank (see Figure 5.5-4) or
the system can be connected to a tank following initial tank placement in the
ground. A sacrificial anode system should not be installed on an existing
tank because the corrosion protection needs for a used tank are difficult to
determine.
The impressed current cathodic protection method employs direct current
(DC) provided by an external source. This current is passed through the
system by the use of anodes such as carbon, non-corrodible alloys, or
platinum. These anodes are buried in the ground (in the case of underground
structures) or otherwise susoended in the electrolyte and connected to an ex-
-------
5.5-19
Figure 5.5-3
Magnesium Sacrificial Anode Cathodic Protection:
Typical Configuration
Tank
Iniertank
Bond Wire
Insulated Bushing
Magnesium Anode
in bag
Coaling
Dielectric
a~ Insulation
Source:
^
Suggested Ways to Meet Corrosion Protection Codes for Underground
Tanks and Piping; The Hinchman Company, Detroit, MI.
-------
5.5-20
Figure 5.5-4
Factory-Installed Sacrificial Anode
ccrlticltl Anodt
Attached *r
Manufacturer
-------
5.5-21
ternal power supply. An impressed current system can be regulated to meet any
level of soil aggressiveness, but, being a highly dynamic design, requires
regular supervision and periodic: maintenance. Generally, an impressed current
system should be inspected at least two times a year, including a check of
soil resistivity each time. A typical impressed current system for
underground tanks and piping is illustrated in Fiqure 5.5-5.
An impressed current system can be installed at any time during the life
of a tank system and such a sys'rem can be adjusted to meet changing protective
current needs. When an impressed current system is operating, all metal
structures within its electrical field must be bonded to the electric current;
any unbonded metal will corrode raoidly under the influence of the impr-essed
current. Nearby gas, water, or utility lines must be protected from stray
currents generated by the impressed current output. When an impressed current
syste-1 is attach tc a used tank systen, it -'s esoecially important that thp
cathodic protection mechanism s performance be regularly inspected and
monitored; otherwise, corrosion on the protected tank system or system or
adjacent metallic structures may be inadvertently accelerated.
There may be some sites that reouire cathodic protection systems designed
specifically for the conditions at the sites, particularly locales with very
low or very high resistivities, Cathodic protection devices must always be
placed within the confines of a lined excavation (the lining acts as an
insulator) or within a concrete vault.
Based on the information obtained under Section 264.191(c)(l), the
corrosion expert will be able to evaluate quantitatively the cathodic
protection needs of a tank system to ensure structural integrity for the
system's intended life. Additionally, under the requirements of Section
264.192(e), a corrosion expert is required to supervise the installation of
the cathodic protection system.
-------
5.5-22
Figure 5.5-5
Impressed Current Cathodic Protection Typical Configuration
Test Box
Anode
Positlvt Hw»d«r
Ractilicr
Negative Bond
Source: Suggested Ways to feet Corrosion Protection Codes for Underground
Tanks and Piping; The Hinchman Company, Detroit, MI.
-------
5.5-23
Electrical Isolation Devices -Electrical isolation devices can prevent
nearby structures from creating an electrical circuit that allows galvanic
corrosion to occur on a tank system. Such devices also are used to isolate a
tank electrically from any metallic anchoring, piping, and pump(s).
Electrical isolation is particularly necessary with a sacrificial anode system
because the amount of metal to be protected must be limited. Otherwise, the
burden on the sacrificial anode cathodic protection system may be increased
drastically, resulting in insufficient corrosion protection.
Isolation devices include electrically resistive envelopes, flange
assemblies, bushings, prefabricated insulating joints, unions, and couplings.
These devices are available to maintain effective grounding and the de'sired
isolation. NACE Standard RP-01-77, "Recommended Practice - Mitigation of
Alternating Current and Lightning Effects on Metallic: Structures and Corrosion
Control System" provides additional information on this subject. A COTOS i
expert who is familiar with the usage of electrical isolation devices will be
able to decide where and how a tank system's electrical isolation needs to be
upgraded.
5.5.2 Major Issue Points
0 Does the facility have adeguate records of tank system materials of
construction and any cathodic protection systems installed?
0 Did the facility accurately compile historical, atmospheric and soil
data that can affect tank corrosion?
0 Is the corrosion expert able to assess adequately the corrosion
potential of the environment surrounding the tank system?
0 Can the corrosion expert determine the type and degree of corrosion
protection needed to ensure tank system integrity for its intended
1ifetime?
-------
5.5-24
Does the facility maintain comprehensive maintenance and repair
records? This is particularly important where impressed current
systems are operating.
If corrosion problems develop, consultation with corrosion experts
should be conducted (i.e., coating/linings applicators, soil
engineers, enqineerina construction consultants, etc.).
-------
6-1
6.0 NEW TANK SYSTEM INSTALLATION
To ensure that each new tank system is structurally secure at the
beginning of operations, Section 264.192(a-e) establishes the requirements for
new tank system installation. Proper tank installation is just as important
as tank design for the prevention of premature structural failure. Tail-
manufacturers have developed detailed, explicit installation recommendations.
If followed carefully, many installation problems that may lead to tank
failure will be avoided.
6.1 REGULATORY CITATIONS
An owner or operator of a new tank system must certify, in writing, t*tat
proper tank system installation procedures have been used. Section 270.16(f)
reauires:
"For new tank systems, a cetailed description of how the tank
system(s) will be installed in compliance with Sec.. 264.192(b), (c),
and (d)."
A qualified installation inspector or a qualified registered professional
engineer and a corrosion expert are required under Section 264.192 to oversee
a new tank system installation.
6.1.1 CITATION: PPE INSTALLATION HANDLING, INSPECTION, AND NECESSARY REPAIRS
The preinstallation requirements of Section 264.192(a) are explicit to
ensure that a new tank system will be structurally secure prior to backfilling
and operation. Section 264.192(a) requires the owner or operator of a new
tank system to:
"ensure that proper hand!ing procedures are adhered to in order to
prevent damage to the tank system during installation. Prior to
covering, enclosing, or placing a new tank system in use, a f
qualified installation inspector or a qualified professional ^
registered engineer who is trained in the proper installation of
tank systems must inspect the system for the presence of any of the
following items:
-------
6-2
(1) Weld breaks;
(2) Punctures;
(3) Scrapes of protective coatings;
(4) Cracks;
(5) Corrosion:
(6) Other structural damage or inadequate construction/instal-
lation.
All discrepancies must be remedied before the system is placed in service."
6.1.1.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
Handling -- Preinstal1ation handling of tank system components,
particularly the tank itself, must be carefully performed so the components
are not scraped, dented, or cracked. Coatings and welds on steel tanks and
the structural integrity of fiberglass reinforced plastic (FRP) tanks 'are
particularly vulnerable to damage from improper handling.
dragged, or rolled. The proper way to move a tank is to lift it, usina
lifting lugs installed by the tank manufacturer. Larger tanks have multiple
lifting lugs and all lugs should be utilized. Cables or chains of adequate
length' should be attached to the lifting lugs, and guidelines should be
attached to the ends of a tank in order to direct the tank's movement (see
Figure 6-1). The intended distribution of a tank load among lifting lugs
should be included in a tank manufacturer's installation instructions.
Generally, however, an included angle of not less than 45 degrees for steel
tanks (see Figure 6-1) is desirable. A spreader bar to separate the hoisting
chains or cables at the appropriate angle should be used, if necessary.
Cables, chains, or slings, should not wrap around a tank shell.
Before a tank is moved, the capacity and reach of hoisting equipment
should be checked. A tank should only be placed on smooth ground that is free
of rocks, foreign objects, vehicles, and vandalism. Rolling movement of a
tank lying on the ground prior to installation, e.g., from high winds, should
be prevented using chocks or rope and stakes.
-------
6-3
Figure 6-1
Liftina and Movino a Tank
Not less than
45° guideline
Isteel tanks
only |
-------
6-4
Inspection A qualified installation inspector or a qualified
registered professional engineer must inspect a tank system before
installation for damage and/or defects. Either individual must have had
experience with similar types of tank system installations, e.g., to inspect
an RP tank for damage or defects, the inspector or engineer must have
participated in other RP ta^k preinstallation inspections. Persons such as a
certified building inspector, a fire marshal 1, a qualified representative of a
tank manufacturing company, or a registered professional engineer can best
fill this role.
The preinstal1ation inspection must consist of a visual examination of
all tank system components (including concrete vaults). Section 264.192(a)
specifically requires that the inspector identify any weld breaks, punctur-es,
scrapes of protective coatings, cracks, corrosion, and other structural damage
or inadequate construction/installation. The presence of these types of
deface and defects c;- :;.sc, 2t *C"'_4', tar- syste~ structural f'Ture.
Without repairs, weld breaks and cracks can render a tank system useless in a
short time. Slower tank system failure may occur from inadequate corrosion
protection caused by damage to a tank's coating, cathodic protection system,
or electrical isolation devices, or from excessive hoisting, causing metal
fatigue. Damage and defects may also cause accelerated local corrosion,
eventually leading to tank system equipment failure. A thorouqh inspection
prior to installation is particularly important for inground and underground
tank systems because when such systems are placed in service, the portions in
contact with backfill gc"e-ai]y ave inaccessible to routine visual inspections.
Damage and defects tend to occur at points of high stress, e.g., at
seams, lugs, points of contact with the ground, couplings, etc. When
observing tank system placement, an inspector should note the occurrence of
any locally high dynamic stresses, for example, placing one tank end in an
excavation before the other end. In this example, the uneven placement may
cause the first end on the ground to bear an unexpectedly large load for a
short time, thus damaging the tank. The individual inspecting a new tank
system must be alert to such instances of careless handling.
-------
6-5
An inspector should also examine a tank following the attachment of
anchoring devices to ensure that these devices do not damage the tank's
protective coating. A checklist of inspection details, including at least the
items listed in Section 264.192(a), should be completed by the inspector.
As stated earlier, FRP tanks are aenerally more vulnerable to damaae
(such as puncture holes) from -improper handling than are steel tanks. Thus,
an inspector should be particularly alert to any instance of mishandlinq prior
to or during the installation of an FRP tank, in order to prevent premature
FRP tank structural failure.
The preinstallation inspection of a tank's ancillary equipment is similar
to that performed for a tank with respect to weld breaks, punctures, scrapes
in coatings, cracks, corrosion and other forms of structural damaae or
inadeauate construction/installation. In addition, however, an inspecto1" of a
tan^ 's ancillary er^'^'ert snc^_ ens:.1-- t^st a11 ccT'inents, i.e., kf°ts,
fittings, valves, and flanges are securely connected.
Repairs On-site repairs of tank system damage and/or defects may be
possible in some instances. Minor structural repairs, such as fixing a 3-4
inch weld break or chipped fiberglass coating should be performed by a
representative of the tank manufacturer. If damage is major or irreparable, a
tank system must not be placed into service.
6.1.2 CITATION: BACKFILL
Section 264.192(b) specifies the requirements for backfill material and
the backfilling process for a new underground tank system. These requirements
were developed to minimize the possibility of external corrosion from the
surrounding environment and to ascertain that a tank is properly supported.
Section 264.192(b) states:
"Backfill material must be a noncorrosive, porous substance. Tanks
that are placed underground must be carefully backfilled so that the
backfill is placed completely around the tank and compacted to
ensure that the tank is fully and uniformly supported."
-------
6-6
Tank manufacturers often provide installation specifications for backfill
material and placement. Prior to installation, the inspector of a new tank
system should include on the inspection checklist an examination of backfill
material and placement.
6.1.2.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARD
Backfill Material -- For an underground tank installation, all excavated
native soil must be replaced with appropriate backfill material. Backfill
below, around, and above a tank should be homogeneous, clean, and properly
compacted. Section 264.192(b) reguires that the material "be a noncorrosive,
porous substance." This material will differ somewhat for steel and composite
tanks, compared to nonmetallic tanks. The use of inappropriate backfall
material can void a tank manufacturer's warranty. Backfill suppliers should
be able to certify material characteristics.
In general, a stee1 o>- composite tank reaui>es backfill that is composed
of washed, well-granulated, free-flowing sand or gravel. The largest particle
should not be larger than 1/8 inch and not more than five percent, by weight,
should be able to pass through a ^200 sieve. In freezing conditions, the
backfill must be dry and free of ice and snow.
For a nonmetallic tank, the backfill should consist of pea gravel,
defined as rounded particles with a minimum diameter of 1/8 inch and a maximum
diameter of 3/4 inch o- crushed rock or gravel, defined as washed and
freeflowing angular particles between 1/8 and 1/2 inch. Not more than three
percent, by weight, should be able to pass through a #9 sieve. As with the
backfill for metal tanks, the backfill should be dry and free of ice and snow.
Placement -- A tank and its backfill act together to provide the
necessary structural support for tank contents and external loads. Tanks are
designed to be flexible and to deflect slightly, displacing backfill, 1n
response to loading. Thus, because a tank is designed to deflect, backfill
-------
6-7
must be placed and compacted uniformly around the tank so that excessive
stresses are not created in any portion of the deflecting tank. A tank must
not be filled before all backfill is in place.
The dimensions of the hole excavated to hold a tank are important. The
hole must be deep enough to contain graded and leveled backfill bedding of six
inches for a steel tank and one foot for an RP tank. At least two feet o*
backfill or not less than one foot of backfill and four inches of reinforced
concrete must be placed above a tank in a non-traffic area (for backfill cover
specifications in an area with traffic, see Section 5.1.1.2.1). Eighteen, or
preferably, 24 inches of backfill is needed between adjacent tanks and between
tank sides and the edges of an excavation. If the depth of backfill cover is
greater than a tank's diameter, the tank manufacturer should be consul ted-to
determine if reinforcement of the tank is desirable. Special cover and
spacing retirements may exist for very large tanks; see manufacturers'
irsI;11 at ion inst-uct " :r s.
Deep pits in unstable soil conditions may require extra support, or
shoring, to prevent cave-ins during installation. In addition, because
backfill provides as much as 90 percent of the tank support for a FRP tank,
manufacturers of such tanks provide special instructions for tank installation
in unstable soil environments (muck, bog, peat, swamp, or landfill areas).
Typical excavation considerations include soil stability, manufacturers'
recommendations, and space for anchors and monitoring wells.
Backfill should be placed carefully along the bottom quadrant of a tank
to ensure that the tank is securely and evenly supported. The compacted
backfill beneath a tank permits the forces present to be dissipated uniformly
over a large area. The backfill base should extend one foot beyond the
perimeter of a tank. No voids (air spaces) should exist around the base of a
tank, nor should intermediate supports (saddles) be used, because these
features can magnify the effects of structural loading and can cause a tank to
rupture. Moreover, water can accumulate in a void, causing accelerated local
-------
6-8
corrosion. A long handled probe can be used to compact backfill under a
tank. Sand backfill usually requires mechanical compacting to provide
adequate tank support and to reduce the possibility of voids forming under a
tank.
An excavation will fill with water if the ground water table is high. A
tank can be installed under such conditions, however, with appropriate
anchoring, ballasting, and/or dewatering of the excavation pit. Ballast level
in a tank must not exceed the water level in the excavation. If dewaterinq is
required, an experience professional engineer, geologist, or hydrogeologist
should be consulted. See also, "Construction Dewaterinq, A Guide to Theory
and Practice," (1981) by J.P. Powers, published by John Wiley and Sons, Inc.
(New York, NY). Permanent tank anchoring will be reauired with this
environmental condition. If a hold-down pad is used (see Section 5.1.1.5.1),
one foot of compacted backfill base ^ust be placed on top of the pad before
seatinc a tar- .
Once a tank has been firmly seated on its backfill base and the tank's
ancillary equipment installed, the balance of backfill may be placed.
Homogeneous clean sand, pea gravel, and crushed rock are relatively
self-compacting and are easy to place. Any debris in the backfill, such as
concrete chunks or rocks, can prevent local deflection of a tank shell and
thus can cause the tank to fail; such debris must be removed from backfill.
Native soil taken from a tank excavation should not be used as backfill unless
its noncorrosiveness and porosity are approved by the installation inspector
or the registered engineer supervising the tank installation.
6.1.3 CITATION: TIGHTNESS TESTING
Tightness testing of a tank and its ancillary equipment can prevent
leaking equipment from being placed into operation. Section 264.192(c)
requires that:
"All tanks and ancillary equipment must be tested for tightness
prior to being covered, enclosed, or placed in use. All leaks must
be remedied before the syst^..> ,» H>-c-J .n service."
-------
6-9
Tests for tightness are generally performed by leak testing experts.
6.1.3.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
Tanks -- All new tank systems, aboveground, inground, and underground,
trust be tested prior to being placed in service. It is particularly important
that a tank system which will be in contact with backfill or soil is tested
for tightness because this type of system will later be inaccessible to
routine visual inspections.
For aboveground and inground tanks, testing for tightness should be made
at operating pressure using air, inert gas, or water. Tightness test
procedures for a double-walled tank should be conducted in a manner approves
by the tank manufacturer. Generally, these procedures involve testing both
the primary and secondary shells simultaneously.
A field-erected tank should :>e tested for tightness in accordance with
good engineering principles and reference should be made to the section(s) on
testing for tightness in the applicable design code (see Table 5-2). In
addition, NFPA 30, "Flammable and Combustible Liquids Code" (1984) accepts the
following procedure as a tightness test for a field-erected tank:
"When the vertical length of the fill and vent pipes is such that
when filled with liquid" the static head imposed upon the bottom of
the tank exceeds 10 Ibs per <;q in. (68.° kPa), the tank and related
pipi-ia s^all be tested hydrostatically to a pressure eaual to the
static head thus imposed. In special cases where the heignt of the
vent above the top of the tank is excessive, the hydrostatic test
pressure shall be determined by using recognized enaineering
practice." (p. 30-21)
An underground tank should be tested for tightness hydrostatically or
with air pressure, before being placed in the ground. To perform a tightness
test, all factory-installed plugs should be removed, doped, and reinstalled
and all tank fittings must be tightened. Seams, fittings, and visible dents
must be thoroughly soaped and carefully inspected for bubbles during an air
pressure test. A pressure gage that accurately measures small changes in
-------
6-10
pressure (1/4 or 1/2 psi) should be used. For an air pressure test, air
pressure should not be less than 3 psi (20.6 kPa) and not more than 5 psi
(34.5 kPa). Air testing with over 5 psi may damage a tank. An air pressure
test should not be performed in equipment that has contained hazardous,
flammable, or combustible material.
Piping -- Piping may be tested hydrostatically at 150 percent (but not
less than 50 psi) or pneumatically at 110 percent of the maximum anticipated
system pressure, respectively. The piping must be disconnected from the
tank. All joints, connections, and dents must be thoroughly soaped. The test
must be maintained for a sufficient time to complete a visual inspection of
all joints, connections, and dents for bubbles, generally 30-60 minutes.
American Petroleum Institute (API) Publication RP 1110, "Recommended Practice
for the Pressure Testing of Liquid Petroleum Pipelines, Second Edition" (1981)
may serve as guidance for hydrostatic testing of pipina.
Repairs -- Before a tank system is placed in service, all leaks
discovered during testing for tightness must be remedied. Minor tank damage
can be corrected on-site, but a major tank system defect may render a tank
system unusable. A repaired tank and/or piping should be retested before
burial. Following placement of a tank in an excavation, before backfilling,
the tank may be retested. Piping can be retested before or after backfilling
the pipe
6.1.4 CITATION: PIPING SYSTEM INSTALLATION
Proper piping system installation practices further ensure the integrity
of a tank system. Section 264.192(d) seeks to regulate these practices, as
follows:
"Piping systems must be supported and protected against physical damage
and excessive stress owing to settlement, vibration, expansion, or
contraction."
-------
6-11
6.1.4.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
Faulty installation of piping and pipe fittings is a major cause of leaks
and spills at liquid storage facilities. Proper piping installation is the
means used to meet the 264.192(d) requirement.
Piping trenches must be large enough to he filled with at least six
inches of backfill around each pipeline. This backfill will protect pipino
from settlement damage, vibration, expansion, contraction, abrasion, and
contact with foreign materials. Disruptive forces on a piping system include
fluid expansion, wind loading, seismic activity, subsidence, and excess
vibration .
A product pipeline should be covered by at least 12 inches of backfill in
an area without traffic and by at least 18 inches of backfill in an area with
traffic. Ve1"!t r'T'^c s^cj"1^ ^e 3* l°3st 12 inches be10'.' t^e aro'Jnd S'Jrfsce
beginning fror the point where the piping rises vertically (or four inches in
a no-load area). Aboveground vent piping should be placed in a location that
protects it from traffic and other sources of damage. All piping should slope
at least 1/8 inch per foot horizontal toward the tank and piping should be
lain carefully to avoid sags or traps in the line that can collect liquid.
Manufacturers' instructions for installation of non-metallic piping should be
followed expl ici tly.
Bedding and covering backfill for buried piping should be composed of a
single material, similar to the tank backfill materials described in Section
6.1.2.1 Backfill compaction and placement specifications are also the same as
for underground tanks. Special care must be taken when compacting over
nonmetallic piping. Before backfilling, any rocks, debris, chocks and bracing
used during trench construction must be removed.
-------
6-12
A piping system should also be designed to prevent expansion or
contraction from causing excessive stresses and bending in the system. For
example, if significant temperature changes are expected, such as in piping
carrying heated oil, the piping system might contain anchors and/or extra
bends, expansion joints, expansion loops, etc. for flexibility. Aboveground
piping can be protected fron expansion and contraction in the same way as
buried piping, but the former reauires consideration of beam bending stresses
and the possible elastic instability of the piping and its supports fro1"
longitudinal compressive forces.
Breakage of underground piping and vent lines and the loosening of pipe
fittings that can cause leaks will be minimized through the use of swing
joints or some othe>" type of flexible coupling. Swing joints should-.be
installed where pipina connects with an underground tank and where piping ends
at a vent riser. Fiberglass pipina does not reauire swina joints if at least
f ou>~ fpp* pf c t"~ 5' c'^ t rj" p^r1"'"? ic r'r cv i d * ^ 3 ^O1" 2nv d^'rpct"?n?^ ch 3n c?
exceeding 30 degrees.
Piping supports must be designed so as not to cause excessive local
stresses in the piping and not to impose excessive axial or lateral friction
forces. All piping attachments must be designed to minimize stresses in the
pipe wall from the attachments. Noninteqral attachments, such as pipe damps
and ring girders are preferred, if they can fulfill the necessary supporting
or anchoring functions.
Braces and damping devices may occasionally be required to prevent piping
vibration. If piping is designed to operate at, or close to, its allowable
stress, all connections welded to the piping must be made to a separate
cylindrical member that completely encircles the piping. This encircling
member must be welded to the piping using continuous circumferential welds.
-------
6-13
A piping trench should be situated so that it does not pass over any
underground tanks and piping should exit a tank excavation by the shortest
route, minimizina crossing of the tank. A piping route should be arranged to
minimize the distance between inlet and outlet. As few trenches as practical
should be constructed.
Connections between pipe lengths and at a tank are a frequent source of
leaks. When pipe is screwed together, thread lubricant (pipe dope) is
necessary to ensure that the piping and fitting are mated to the proper dept^,
to ensure that a tight sea1 has been made, and to provide some decree of
protection against the crevice corrosion that can occur at joints. Where
threads are joined, the union of two metals with just slightly different
properties can result in a galvanic cell that will corrode if not protected.
Thread lubricant gives limited protection to joints. The practice of welding
galvanized pipe fittincs is uncommon and is unsuitable for underground pining
systems .
FRP joints should be glued, except where transitions to pumps and
emergency shutoff valves are made. Relatively thin-walled (Scheduled 10)
stainless steel pipe may be used For low pressure piping. The joints for this
Schedule 10 piping should be welded. Welding stainless steel is an operation
requiring considerable skill and attention to detail. Where screwed
connections are required, such as for the pump connection, a transition to
Schedule 40 pipe must be made, "he Schedjle ^0 pipe has sufficient thickness
to allo.' for pipe threads to be cut.
The joining methods for double-walled piping include flanges, welding,
and resin-gluing. The exact method depends on the specific type of piping
chosen. Manufacturer's specifications should be consulted for more detailed
information.
-------
6-14
The following references can assist in the installation of piping system
supports and protection:
o API Publication 1615, "Installation of Underground Petroleum Storaa^
Systems" (1979);
o ANSI Standard 831.3, "Petroleum Refinery Pipina" (1984);
o ANSI Standard B31.4, "Liquid Petroleum Transportation Piping
Systems" (1980), and;
o Piping manufacturer installation instructions.
Figures 6-2 to 6-4 present piping system installation details.
6.1.5 CITATION: CORROSION PROTECTION INSTALLATION
To ensure that a new tank system has adeauate corrosion protection, the
r^.mor- QV oD<=r-ato>- T'jst utilize a cohesion expert to supervise the
installation of a cathodic protection system. AS specifiec in Section
264.192(e):
"T-he owner or coeratcr must provide the type and degree of corrosion
protection determined by the Regional Administrator to be necessary to
ensure the integrity of the tank system for its intended life, based on
the information provided under §264.191(c). A corrosion expert must
supervise the installation of any cathodic protection system."
6.1.5.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
Using the information obtained under Section 264.191(c), a corrosion
expert (defined in Section 5.5.1.1.1) will be able to determine the cathodic
protection needs of a tank system for its intended lifetime (Section
5.5.1.2.1). A corrosion expert must oversee the installation of any cathodic
protection devices for a new tank system.
-------
6-15
Figure 6-2
Tank Piping Details - Suction System
SUCTION LINES TO .EXTRACTOR INGLE
PUMP ISLANDS (SLOPE ICHECK VALVE ASSY.
MANHOLE
,FlLL CAP
VtHT LINE TO APPROPRIATE
LOCATION (SLOPE TO TANK)
ANGLE CHECK MftLVC 0*
UNDER PUMP CHK VALVE. MO
/RISER REO'D. */EARTH COVER
^X^;;
EXIST SOIL
(UNDISTURBED)
^H"
MIN
' \ ^^/f
! ^BUSHING/ /
J/I6"HOLE/
. (OPTIONAL)
1 i
, ^SUCTION TUBE
^ ' £l" M N
t TANK
yFlLL TUiE
i STORAGE
V 6 IMAX.
₯-
v
!
i
1
./SUCTION
fTUtl
' TANK
J ~^~
X^
<
MIN.
-OVERFILL PREVENTION
FLOAT VENT VALVE
- SAND OR ORAVEL 6
DETAIL; ro« TANKS UNDER CONCHCTE
i-t. rcl K;».
. ' C TANKS (OR
MFR.APPP.OVtD ALTERNATE)
SCA.E
Figure 6-3
NOTE ELIMINATE COHC SLAB IN
TMAFFlC AREAS t CONSTRUCT
CONC. PADS (ONLY) AROUND HAN
MOLES. THE EXTR. AN9LE CHICK
RISER IS NOT REO D W/EARTH
COVER.
Tank Piping Details - Submerged System
MANIFOLD ASSY
TO APPROPRIATE
(SLOPE TO TANK)
MANHOLE
SLOPE ^
\ , FILLCAP
\^ \ 1 ' SLOPE (TYP)
X»EINF CONC. SLAB
<-,. .-.'. '.\, ^ \ ,r- :.',*-.- 1 <*.*,..- : .-....-..- .''fl
LEAK DETECTOR
VP-.-^-CL'AY TILE ,DOU»LE SWING JOINT
i'.-l1 ~ GRAVEL ^ ^^~^
I'.'-!'-«:» c i. L PIPE f^ 1-^^
^ 7"| [|-; ' -TT* n L L rirt Q u-
/ '6 '^r'
DOUBLE SWING $
JOINT It
SUPPLY LINE TO *-**
PUMP ISLANDS MIN
PUMP 6 MOTOR y^
'I6GA SQUARE f*. PLUe^NIPPLE'''^*"
i METAL FRAME nl X^^ /
1 5/16" MOLE ' XBUSHING -'
I (OPTIONAL) '(L £ OF TANK
h '''
T' STORAGE TANK
' ' 'L FILL TUBE
-*l j |'|
w' l f*"«AX.
TS'MIN I
"^~^-OVERFILL PREVENTION
FLOAT VENT VAJ.VE
- SAND OM MAVIL &
lli-fc^ EXIST. SOIL
JjjTj' (UNDISTURSED)
^1
t.
^
PIPING DETAILS FOR TANKS UNOCR CONCRETE
i PEA ORAVEL FOR NON -
METALLIC TANKS (OP
MFR APPROVED ALTERNATE)
NO SCALE NOTE: ELIMINATE CONC. SVAB IM NON-
TRAFFIC AREAS CONSTRUCT
CONC PADS (ONLY) AROUND M. H.
Source: API 1615, p. 9.
-------
6-16
Figure 6-4
Miscellaneous Piping System Details
n
GUTTER
I I
NIPPLE
45° ELL.
BRACKET
"U"BOLT/
-VENT LINES
. 2'-0"(MIN.)
ROOF
FASTEN BRACKET TO BUILDING W/
EXPANSION OR TOGGLE BOLTS
WOOD BLOCK
FRONT VIEW
BLDG UNE
SIDE VIEW
VENT DETAILS
NO SCA^E
TYPICAL SWING JOINT
(ISU*ND VENT
NO SCALE
Source: API 1615, p. 10.
-------
6-17
The National Association of Corrosion Engineers (NACE) Standards RP-02-85
and RP-01-69, "Recommended Practice - Control of External Corrosion on
Metallic Buried, Partially Buried, or Submerged Liquid Storage Systems" (1985)
and "Recommended Practice - Control of External Corrosion on Underground or
Submerged Metallic Piping Systems" (1983), respectively, contain information
on cathodic protection syste^ construction, inspection, handling, electrical
isolation, and installation details. See Section 5.5.1.2.1, for additional
information on cathodic protection system installation.
6.1.6 CITATION: CERTIFICATION
Following installation, the owner or operator of a new tank system must
obtain, as per Section 264.l92(f):
"written statements by those persons required to supervise the
installation of tank svste^s in accordance with the retirements of
paraaraphs (a)-(e) of tms section whicn attest t-iat the tank syste-
was properly installed. [The statements] must be kept on file at
the facility. These written statements must also include a
certification as required in §270.11 (d)."
6.1.6.1 GUIDANCE TO ACHIEVE THE PART 264 STANDARDS
The installation inspector or the professional engineer, the tightness
tester, the corrosion expert, and anyone else who has supervised a portion of
the installation of a new tank system must document that the installation is
in accordance with the requirements of Section 26^.192(a-e). Materials
accompanying and supporting these statements might include "as built"
installation drawings and photographs of tank and piping components.
A sample statement of the form required by Section 264.192(f), including
the Section 270.11 (d) truthfulness certification, follows:
I, [Name], have supervised a portion of the installation of a
new tank system located at [Address], and owned/operated by
[Name(s)]. My duties were: [e.g., preinstallation inspection,
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6-18
testing for tightness, etc.], as required by the Resource
Conservation and Recovery Act (RCRA) regul ation(s), namely, 40 CFR
264.192 fApplicable Paragraphs (i.e., a-e)].
I certify under penalty of law that I have personally examined
and am familiar with the information submitted in this document and
all attachments and that, based on my inquiry of those individuals
immediately responsible for obtaining the information, I believe
that the information is true, accurate, and complete. I am aware
that there are significant penalties for submitting false
information, including the possibility of fine and imprisonment.
Si onature
Title
Registration Number, if applicable
Address
The certification statements must be kept on file at the tank facility,
as specified in Section 26£.19?(f).
6.2 MAJOR ISSUE POINTS
1. Is the installation inspector or registered engineer qualified to
inspect a new tank system pno^ to installation? Can this
individual discriminate between reparable and irreparable damaaes
and defects? Can he/she assess the adequacy of a repair?
2. Is the backfill homogeneous, noncorrosive, porous? Are the
dimensions of the tank excavation adequate? Has the backfill been
placed and compacted carefully around the tank?
3. Does the tank pass a test for tightness? Does the piping system
pass an analogous test?
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6-19
4. Is the piping system adequately supported and protected against
damage from external and internal loads?
5. Is the corrosion expert qualified to supervise the installation of
an appropriate cathodic protection system?
6. Are written statements by the installation inspector and/or the
reaistered enginee** and by the corrosion expert certifying as
required in Section 270.11 (d), that the tank system is properly
installed, on file at the facility?
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7-1
7.0 SECONDARY CONTAINMENT SYSTEM PLANS AND DESCRIPTION
The Section 264.193 regulations require all new tank systems to have full
secondary containment and all existing tank systems to have either full
secondary containment or, partial secondary containment or leak testing, in
combination with a ground water monitoring program (see Section 8.0 for
information on around water monitoring programs). Table 7-1 lists the
containment requirements for each type of tank system. The combination of
secondary containment and the ground water monitoring alternative (leak
testing and a ground water monitoring program) for an underground tank is not
required under Section 264 because a properly designed secondary containment .
system, alone, will adequately protect human health and the environment.
Full secondary containment for a hazardous waste storage or treatment
tank system includes a means for detection of the presence of liquids within
the containment device and a means for collection and removal of any released
materials. Partial secondary containment includes methods for detection and
removal of-released materials, but only the aboveground portions of the tank
system are within the containment. According to Section 264.193(f), partial
secondary containment shall consist of a leak-proof lined base and diking that
meets the requirements of Sections 264.193(a),(b), and (d)(l).
Secondary containment provides protection of human health and the
environment by preventing the release of waste to surface water, qround water,
and soil from tank structural failure. In addition, secondary containment
provides protection from spills caused by operational errors, such as
overfilling.
The retrofit of full secondary containment beneath an existinq tank
system may prove to be impractical without completely dismantling or
destroying the tank. Additionally, retrofitting a very large tank may not be
cost-effective. Thus, an existinq facility may choose to implement a ground
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7-2
Tab'e 7-1
Containment Approach
Type of Tank System
Containment Reauirements
Hazardous Waste Storage and
Treatment Tank Systems
New
Existing
(abovearound and inaround'
Existina
(underground)
Full secondary containment
Within one year of effective date
provide:
full secondary containment
or
partial secondary containment
and
around water monitoring
Within one year of effective date
prov ide:
full secondary containment
or
ground water monitoring
and
leak testing every six months
90-day Accumulation Tank Systems
New
Existing
Full secondary containment
Full secondary containment within one
year of effective date or aoply for a
Part 264 permit
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7-3
water monitoring program instead of full secondary containment; however, the
facility must also provide secondary containment for any portions of a tank
system that are aboveqround and semi-annual leak testing (see Section
5.1.1.1.1, p. ) for an underground system.
An aboveground tank may have its bottom on the ground in contact with
soil. If the size of such a tank makes it impractical for the owner/operator
to retrofit the tank with full secondary containment, a ground water
monitoring program (and periodic inspections, see Section 11.0) may be
implemented, along with full secondary containment, minus the bottom of the
tank. A tank foundation is not considered secondary containment by EPA.
A 90-day accumulation tank system is reauired to have full secondary
containment (includinq leak detection and removal mechanisms) within one year
of the effective date of the Section 264 regulations, else the tank system
owner or operator must apply for a RCRA permit. Because of the need for
interaction between EPA and the owner or operator of a tank system for a
ground water monitoring program to be implemented, such a program is not
considered viable for a 90-day accumulation tank system.
A tank system owner or operator needs to consider factors such as the
complexity of a ground water monitoring and response proqram, the size of a
tank facility, and the cost of retrofitting the facility with secondary
containment, before selecting between secondary containment and the ground
water monitoring alternative. In many cases, full secondary containment for
an existing tank system, although initially capital intensive, proves to be
comparable in cost with the ground water monitoring alternative when costs are
annualized over a 20-year tank system lifetime. Additionally, with full
secondary containment and release detection and removal mechanisms in place,
any potential corrective action costs for releases to the environment can be
avoided.
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7-4
The types of tank secondary containment systems that are acceptable under
Section 264.193(c) are liners (external to tanks), vaults, double-walled
tanks, and equivalent devices, as approved by a Regional Administrator. A
liner constructed of low permeability material (such as clay) or of synthetic
membrane (such as polyvinyl chloride), coats the edges of a tank excavation to
prevent migration to the environment of any released substances. A vault,
generally constructed of concrete and lined with a nonporous coating (reauired
under Section 264.193(d)(2)(ii)), act-; as a chamber that contains any released
materials. Most vaults are designed to allow inspection of the enclosed tank
for leaks. A double-walled or wrapped tank holds leaked tank materials in the
interstitial space between the inner and outer tank walls, thus preventing
releases to the environment.
7.1 Regulatory Citations
Information pertaining to secondary containment system plans and
description must be included in Part B of the permit application, as specified
in Section 270.16(g), "Detailed plans and description of how the secondary
containment system for each tank system is or will be designed, constructed,
and operated to meet the requirements of Section 26A.193(a), (b), (c), (d),
and (e)."
7.1.1 Citation: Characteristic Properties of a Secondary Containment System
As specified in Section 264.193(a) of the Part B permit application
regulations, a tank system with secondary containment must be designed,
installed, and operated with a containment system that:
"(1) Prevents any migration of wastes or accumulated
precipitation out of the tank system to the soil, ground
water or to surface water at any time during the use of
the tank system;
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7-5
(2) Detects and collects any releases of waste and accumulated
precipitation until the collected material can be removed;
(3) Removes or permits the removal of spilled or leaked waste
and accumulated precipitation in as timely a manner as is
necessary to prevent releases from the secondary
containment system."
7.1.1.1 Guidance to Achieve the Part 264 Standard
The intent of the reauirement for ful 1 secondary containment of a new
tank system is to ensure that releases of waste to the surrounding environment
fare not viable. Thus, Section 264.193(a) lists the necessary characteristic
design properties of an effective secondary containment system. The design.
properties described in Section 264.193(a) are elaborated upon in Section
264.193(b) (see Section 7.1.2.1). Section 26
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7-6
(3) A secondary containment system must have a leak detection
system.
(4) A secondary containment system must be sloped or operated to
drain and remove any accumulated liquids.
(5) A secondary containment system must be designed to retain 110
percent of the design capacity of the largest tank within its
boundary.
(6) A secondary containment system must be designed to prevent
run-on and infiltration of precipitation. Otherwise, the
system must have sufficient capacity to contain precipitation
from a 25 year, 24 hour storm.
7.1.2.1 Guidance to Achieve the Part ?64 Standard
The relevant design parameters for a tank system's secondary containment
system are described in Section 264."i93(b). Such a system must be able to
hold any released waste for up to 48 hours, if 24 hours is needed for
detection^ ' and another 24 hours is needed for removal. If liquid is
found in a secondary containment system from a tank leak, action should
immediately be taken to minimize the release quantity by stopping the flow of
waste to the tank and by emptying the tank's contents into a secure
containment device (another tank or container). The Section 264.193(b)
secondary containment design requirements are discussed in the following
subsections.
7.1.2.1.1 Compatibility and Strength
According to Section 264.193(b)(l), a secondary containment liner or
material of construction must be compatible with its contained waste(s). Such
a requirement may be met by selecting a containment liner resistant to attacks
(I)Accordingtothe "Preamble to the Proposed Rule on Standards for
Hazardous Waste Storage and Treatment Tank System" regulations, Federal
Register, Vol. 50, No. 123, p. 26467.
(2) Ibid., p. 26468.
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7-7
by sulfides and acidic wastes, for example. The requirement is necessary to
ensure the containment's integrity, thus preventing releases to the
surrounding environment.
As described in Section 5.1.1.1.1, the owner or operator of a tank system
must perform a detailed chemical and physical analysis of contained waste(s).
This data, along with information from the Chemical Engineers' Handbook, the
National Association of Corrosion Engineers (NACE), tank, liner, and resin
manufacturers, on-site facility tests, and any other relevant sources may be
ued to convince EPA of the compatibility of a stored waste and its secondary
containment. The EPA document entitled "Lining of Waste Impoundment and
Disposal Facilities" (1980) provides extensive information and references on
establishing waste-liner compatibility.
It is necessary to consider all waste constituents when assessing the
compatibility of a secondary containment liner or material of construction in
a given storage or treatment application. When multiple tanks are within a
single secondary containment area, an owner or operator is advised not to
place wastes incompatible to each other or wastes that can combine to form a
mixture that is incompatible with the containment in these tanks. Note that
Section 264.193(d)(2)(ii) requires secondary containment concrete vaults to be
provided with a nonpermeable coating that is compatible with any stored waste.
Secondary containment strength, generally a direct function of thickness
for a given material, must be adequate to prevent failure. The stresses that
Section 264.193(b)(l) are concerned with are from:
o pressure gradients, both vertical (from tank weight and any
backfill) and horizontal (from external hydrologic pressure);
o waste contact, if the primary containment fails;
o adverse climatic conditions, such that the physical properties
of a secondary containment system are altered;
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7-8
o secondary containment installation; and
o daily operational activities, including nearby and overhead
vehicular traffic.
Static vertical pressure gradients on a tank's secondary containment
system are generally not troublesome if installation of the tank and its
containment are performed properly, "he static pressures below and above a
containment should be in relative balance if the containment is adequately
protected from punctures and other forms of uneven load distribution (e.g., an
underground tank seated improperly on backfill). Adequate separation of an
inground or underground tank from its secondary containment using homogeneous,
rounded, porous, well-compacted backfill material (see Section 6.1.2.1) will.
protect the containment (liner or vault) from damage.
Aboveground tank secondary containment must be kept free of debris, etc.,
to protect the integrity of the containment material. Settlement,
compression, and uplift of secondary containment systems must be prevented for
all types of tank systems (aboveground, inground, and underground).
Horizontal pressure gradients, generally, are only a concern for an
inground or an underground tank located in a region with a high ground water
table. If the ground water table is higher than the lowest point of a
secondary containment system, the resulting inward pressure may be
significant. If a liner is to be installed in an area of high ground water,
the site must be dewatered until the liner, the tank, the piping, and the
backfill have been installed. The backfill will more than offset the pressure
or buoyant force exerted by the ground water once dewatering has been
terminated. Liners and coatings on concrete vaults should be thick enough so
they remain impermeable in high ground water conditions. Test results on the
waterproofness of a material, over time, are useful to establish long term
integrity for a secondary containment material.
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7-9
A tank's secondary containment must be strong enough to retain any
released waste material until removal can occur. Thus, the containment must
be compatible with a stored waste and structurally secure to eliminate leakage
through the containment.
Adverse climatic conditions can change the physical properties of a
secondary containment system, potentially jeopardizing its strength and
integrity. Test results on the ability of a containment material to withstand
extremes in temperature, excessive moisture, ultraviolet radiation, high
winds, etc., are useful to predict the ability of the material to remain
secure.
The stresses of installation must be minimized so they do not harm a
secondary containment system. The qualified installation inspector or the
qualified registered professional engineer who is observing new tank system
installation (see Section 6.0) should ascertain that the secondary containment
system is carefully installed, so undue stresses are not placed on the liner
material, the concrete vault or its coating, or the double-walled tank. The
containment materials must be strong enough, however, not to be damaged by
routine installation stresses.
The overhead stresses of daily operation, such as from vehicular traffic,
will not have significantly adverse effects on a secondary containment system
if the tank system is installed and operated using the methods recommended in
Section 5.1.1.2.1. Site-specific conditions must be considered when
determining if a secondary containment system has sufficient strength to
maintain its integrity in the presence of any operational stresses. Such
conditions may include traffic, heavy equipment, winds, precipitation, frost,
and ground water level (buoyant forces for underground and inground tanks).
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7-10
7.1.2.1.2 Foundation Integrity
Section 264.193(b)(2) requires secondary containment to be properly
supported in order to prevent structural failure from settlement, compression,
or uplift. As discussed in Section 7.1.2.1.1, vertical pressure gradients
should be relatively in balance if the backfill surrounding the containment is
homogeneous, rounded, and porous. Compressive stresses ought not to be
harmful to secondary containment material if the backfill does not contain any
debris or significant liquid from precipitation (the containment is required
to have a liquid removal mechanism, as per Section 264.193{a)(3)). The
backfill below a containment should be compacted prior to .containment
placement, particularly well-compacted for concrete vaults, to prevent
settlement.
In an area with a high ground water table, a coated concrete vault or an
anchored double-walled tank is the preferred method of secondary containment.
A vault or an anchored double-walled tank is less likely to fail from uplift
under this environmental condition. The water table at a tank facility may be
either consistently or seasonally high.
7.1.2.1.3 Leak Detection Capability
The leak detection portion of a secondary containment system, required
under Section 264.193(a)(2) and described in more detail in Section
264.193(b)(3), is one of the most important components of a containment
system. Early warning leak detection systems provide continuous surveillance
for the presence of a leak or spill. The types of early warning monitoring
systems most widely used in underground and inground tanks are:
o Systems that monitor the storage tank excavation. These types
of systems include wire grids, observation wells, and U-tubes.
The types of leak sensors used in these systems include:
electrical resistivity sensors,
thermal conductivity sensors, and
gas detectors;
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7-n
o Interstitial monitoring; and
o Inventory monitoring (also called inventory control)
These leak detection systems are described below.
Tank Excavation Monitoring Systems. There are several types of leak
monitoring systems that may be employed using the leak monitoring sensors
described below (in Leak Sensors) to detect leaks in or around an underground
or inground tank storage area. These leak monitoring system types include the
following:
o Wire grids.
o Observation wells.
o U-tubes.
Table 7-2 shows the applicability of the various leak sensors to the
different tank excavation monitoring systems.
Wire Grids. This type of leak monitoring system employs electrical
resistivity sensors in a wire grid located either within or just outside the
containment region (e.g., just inside or outside the containment area's
synthetic liner). The wire grid is connected to a minicomputer that
continuously monitors the electrical properties of each wire in the grid. If
a leak occurs, the mini-computer can determine which wires in the grid have
had their electrical properties altered, thereby identifying the location and
extent of a leak. In the presence of a leak, the insulation around a grid
wire or the wire itself will be dissolved, thereby registering a change in
resistivity. A drawback of this type of system is that it is susceptible to
disabling by a spil1.
Observation Wells. Observation wells are commonly used in areas of
high ground water. The wells typically consist of a four-inch diameter
(schedule 40) polyvinyT chloride (PVC) pipe driven into a tank excavation.
The wells are constructed with a well screen extending a minimum of five feet
-------
7-12
Table 7-2
Applicability of Types of Leak Sensors
Sensor Type
Surveillance Method
Wire
Grids
Observation
Wells
U-tubes
Thermal Conductivity
Electrical Resistivity
Gas Detectors
Samp!ing
X
X
X
X
X
X
X
X
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7-13
into the ground water or two feet below a tank bottom, whichever is deeper, to
at least five feet above the water table (see Figure 7-1). Wells typically
have a slot size of 0.02 inches, are extended to grade, and are covered with a
waterproof cap that is capable of sealing. If slots are large enough to
permit backfill to enter the well casing, the casing should be wrapped in
filter fabric before backfilling.
U-tubes. A U-tube typically consists of a four-inch diameter (schedule
40) PVC pipe, installed as shown in Figure 7-2. Another design configuration
has multiple U-tubes, installed perpendicularly to the length of a tank. The
tank excavation bottom must be sloped a minimum of 1/4 inch vertical per f£>ot_
horizontal toward the U-tube to permit collection of any leaked material. The
horizontal segment of the pipe is half-slotted (typical slot size, 0.06
inches), wrapped with a mesh cloth to prevent backfill infiltration, and
sloped toward a sump, with a slope of approximately 1/4 inch vertical per foot
horizontal. At the higher end of the horizontal pipe, there is a 90 degree
sweep to a vertical pipe that is extended to grade. At the lower end of the
horizontal pipe, there is a tee connection with another vertical pipe; this
vertical pipe is extended to grade, and to two feet below the tee to act as a
collection sump. All vertical pipe sections are unperforated and the bottom
of the sump is sealed, to be leak proof. The openings at grade are provided
with watertight caps which can be sealed. It is imperative that all openings
be secured against products accidentally being delivered into them. U-tubes
can be designed to allow pressurized flow to force collected liquids to be
evacuated (i.e., removed) or collected liquids can be pumped out.
The U-tube is a relatively new design which has not been extensively
tested in the field. It appears to offer an economical method for monitoring
and recovery of leaks and spills at underground installations. When installed
with an underlying impervious liner, a U-tube will collect all liquids moving
downward through the soil in the vicinity of a tank, including rainwater.
This design provides positive assurance of collecting a leak from a tank, but
presents a problem with removal of rainwater which can flood out the leak
detection/collection system. A waterproof excavation cap will eliminate this
oroblem.
-------
7-14
Figure 7-1
Observation Well Installation
Wit«rproo»
- <
'Ground Water
w
t=r
T«nk
Gr«d«
2'min
v
-------
7-15
Figure 7-2
U-tube Installation
Orad*
Waterproof (bio Cap*
2* Ooop tvMp
eeled Cap-
T«nk
Half-tiottotf Pip* Wrapped with Filler Material
-------
7-16
U-tube systems are effective only in areas of low ground water, where it
is unlikely that a tank will be exposed to ground water during normal
operations. U-tube installations, however, can be used in conjunction with
observation wells in areas where the ground water table is known to fluctuate
to a level above the bottom of a tank excavation.
Leak Sensors. A tank excavation monitoring system, described above, is
designed to detect a spill or leak before contamination spreads beyond a lined
tank excavation or a vault. The leak or spill sensing devices that may be
?
used in tank excavation monitoring systems include thermal conductivity
sensors, electrical resistivity sensors, and gas detectors. Direct sampling.
can also be used in the case of observation wells and U-tubes to pinpoint the
occurence and source of a leak. See Table 7-2 for leak sensor applicability.
The following subsections describe the various leak sensors.
Thermal Conductivity Sensors. A thermal conductivity sensor detects
changes in the thermal conductivity of its surrounding environment to
determine if a leak or spill has occurred. These sensors can be used in wet
or dry applications and are particularly applicable for the detection of
hydrocarbons such as alcohols and trichloroethylene.
A system using a thermal conductivity sensor typically consists of an
electronic control device that is connected by cable to a thermal conductivity
probe. The probe is fitted with a thernal conductivity sensor that determines
if a monitored area is dry, wet with water, or wet with some other substance.
The control device may be located up to 1,000 feet from the probe and can
continuously indicate the site condition using indicator lights. A nonwater
liquid presence may be indicated by an audible alarm and recorded by a chart
recorder. A relay contact that can activate external alarms, recovery pumps,
or other automatic controls can also be provided.
When used to monitor the ground water table, one thermal conductivity
sensor located in a monitoring well will only indicate the presence of
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7-17
contamination, but not the extent of it. By using several sensors located at
various levels in the ground water, the thickness of a contaminant layer may
be ascertained.
Electrical Resistivity Sensors. A system employing this leak detection
device relies on the change in resistance of a wire from exposure to a stored
product to indicate the presence of a leak or spill. The key to sensors of
this type is the use of wires or wire coatings that are highly susceptible to
jdegradation when exposed to stored product. For example, bare steel wires may
be used in acid storage areas or bare aluminum wires may be used in caustic
storage areas. If a stored liauid is not corrosive to metal wire, the w?re.
must be coated with a degradable material, such as a rubber coating in areas
storing aromatic solvents. The wires are, in turn, connected to an electrical
device that passes current through them. Any degradation of the wire or its
coating will result in a significant change in circuit resistivity, indicating
the existence of a product leak or spill.
Electrical resistivity sensors are applicable for either wet or dry
excavation (i.e., high or low ground water) applications. Ambient temperature
and soil moisture should have minimal effects on a sensor of this type,
particularly in applications involving coated wires. The drawbacks of this
type of leak detection device include the following:
o Once a leak has been detected, the sensing wire must be
replaced.
o The sensors cannot be used in a previously contaminated well or
soil unless the contamination has been removed. Otherwise, the
sensors will deteriorate rapidly and require replacement.
The control units associated with electrical resistivity sensors can be
designed to interface with audible alarms, visual alarms (e.g., indicator
lights), control equipment such as pumps or valves, and computers. Occasional
checks of systems of this type are required to ensure that the power supply
and the controls are in working order.
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7-18
Gas Detectors. Gas detectors are available to detect a large number of
combustible and non-combustible gases and vapors. These devices are generally
applicable in areas of permeable soil or backfill, where gases and vapors are
likely to migrate easily. Gas detectors are particularly applicable in
instances where a stored waste is highly volatile and the storage excavation
is relatively dry (free of ground water).
There are a wide variety of both portable and permanent gas detection
devices available that may be operated in conjunction with audible or visual
alarm systems.
Interstitial Monitoring. An early warning monitoring technique used in
double-walled tanks involves monitoring the space between the inner and outer
walls of a tank, using either a pressure or a fluid sensor. A pressure sensor
may be used to monitor a tank that either has a vacuum in the space between
the walls or that has the space pressurized. Failure of either the inner or
outer wall is detected by a loss of vacuum or pressure.
Fluid sensors may be employed between the tank walls to detect the
presence of a liquid. The liquid may enter the interstitial space because of
failure of the inner wall (leaking stored waste) or of the outer wall (leaking
incoming water). In an area of High ground water, a fluid sensor is
preferable to a pressure sensor because failure of the outer wall will result
in water ingress. A pressure sensor is preferable in a dry hole excavation
because no liquid will enter the interstitial space if the outer wall fails.
Fluid sensors may be used at atmospheric pressure in vaulted tanks.
The detection of leaks in aboveground tanks can be achieved by visual
inspections and with the use of leak detection instruments. When large tank
farms are involved, a combination of regular inspections, leak monitoring, and
a preventive maintenance program should be used.
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7-19
Visual inspection is the simplest method of aboveground tank leak
detection. It is commonly used in small storage facilities. This method is
most effective when:
o Regular inspections are scheduled and assigned to designated
personnel.
o The method is used in conjunction with a regular maintenance
program.
4 Many of the sensor types that are employed to detect or monitor spills
from underground storage facilities apply to aboveground facilities. These
include the following:
o Thermal conductivity sensors.
o Electrical resistivity sensors.
o Sensors that monitor the interstitial space of a double-walled
tank.
Thermal conductivity and electrical resistivity sensors may be used in
either of the following manners to provide continuous monitoring of
aboveground storage facilities:
o Sensors may be placed in a collection sump or a dry well within
the containment area around an aboveground tank.
o Sensors may be located underneath an aboveground tank or
piping.
Sensors used in wet well (collection sump) applications may be anchored
in the collection sump, or they may be mounted on a level detection float.
Precipitation infiltration must be prevented, however, so false leakage alarms
are not triggered. Sensors used in dry well applications may be mounted
directly on the wall of a well.
Leak monitoring sensors may be placed under an aboveground tank. An
example of such an application is a wire grid system (using electrical
-------
7-20
resistivity sensors) under a tank that is used to monitor leaks from the
bottom of the tank. Such a system can be used to monitor an aboveground tank
in an instance where the bottom of the tank is not accessible to visual
inspection.
Table 7-3 summarizes the capabilities of the various leak detection
techniques.
Inventory Monitoring. Inventory monitoring, measuring the inputs and
a
outputs to a tank and calculating their difference to identify a leak, can
enable an owner or operator to detect a large volume leak. Inventory
monitoring practices require a person to examine (preferably, daily) a tanK
system regularly. Inventory monitoring provides a first line of defense
against large leaks (close to one percent of throughput).
There are a number of factors that limit the accuracy of inventory
control as a leak detection method, however. These include the following:
o Product thermal expansion. Fluctuations in temperature can
lead to expansion, contraction, evaporation, and/or
condensation of a stored waste, thereby affecting inventory
monitoring results.
o Errors associated with faulty reading of dip stick
measurements.
o Errors associated with resolution of meter readings. All
meters have an associated level of error, typically on the
order of 0.5X of the level of resolution of its meter.
o Sludge removal, chemical additions, and recirculation can make
accurate monitoring of a treatment tank difficult.
Furthermore, treatment tanks are often open-topped and thus
subject to climatic conditions (e.g., losses from evaporation
and gains from precipitation).
o Accurate inventory monitoring may be difficult if hazardous
waste is delivered to a tank via gravity flow.
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7-21
Table 7-3
Comparison of Various Leak Detection Techniques
Thermal
ConductiMtv
Sensor*
Elccinc
Resis'.ivuv
Sensors
Gas Detectors
Uses « probe thai delects the
presence of stored product b\
measuring thermal
conducts n>
Consists of one or a series of
sensor cables that deteriorate
in the presence of the stored
product. thereb> indicating a
Used to monitor the presence
of ha2ardous gases in vapors
in the soil
Can monitor
groundwater or
normallv drv
areas
Can monitor
normal)) drv
areas
Areas of highh
permeable. dr>
soil, such as ex-
cavation backfill
or other per-
meable soils.
above ground-
water table
Anv liquid Medium Pnmar) advantage is earlv
detection which makes it possible
for leaks and spills to be cor-
rected before large volumev os
material are discharged 1>pic«n-
Iv requires V, inch ol product on
groundwater to guarantee Orirc-
tion of product water interface
in wet (groundwatcr)
applications | Ib)
An) liquid Medium Pnmarv advantage i^ the cjnv
detection ot spii:v Orrcc a u_»,
or spill is detected the sensors
must be replaced Can detect
small a- well as large leaks
Highl) vol- Medium Once the comammam is present
atile liquids. and detected gas detectors are
such as no longer of use until comamm-
gasolme ation has been cieaneo up
Interstitial
Monitoring
in Double-
Walled Tanks
Monitors pressure level or
vacuum in space beiwecn
walls of a double-walled tank
Double-walled
tanks
Pressure
monitor tank
integnu and
re appli-
cable with
an> stored
liquid Fluid
tensors mon-
itor presence
of an) liquid
in a normalK
dry area, and
are also
applicable
with any
stored liquid.
High Accurate techr.iaue which is
applicable war, an> doubie-
walled tanks
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7-22
Given these limitations in accuracy, even a carefully conducted inventory
monitoring program can only detect leaks that are an appreciable fraction
(typically, 0.75%) of stored volume. For these reasons and the reasons
discussed in the "Preamble to the Proposed Rule on Standards for Hazardous
Waste Storage and Treatment Tank Systems" (50 R 26448-26449), EPA has decided
that inventory monitoring is not sufficient to detect leaks from hazardous
waste tanks.
,7.1.2.1.4 Adequate Drainage
Section 264.193(b)(4) states that a secondary containment system must he
sloped or otherwise designed and/or operated so liquids detected by the
leak-detection system will drain and can later be removed. Typically, any
released tank contents will drain along the top of a sloped containment (liner
or vault) or through a porous drainage layer within the containment to reach a
sump, trough, or similar device (Figure 7-3). The accumulated liquids can
then be withdrawn by siphoning or pumping from a collection area.
An aboveground containment system must be surrounded by impermeable curbs
(usually of concrete or asphalt), gutters, dikes, etc., as needed, to prevent
flow from leaving the containment area. Asphalt or concrete curbs or dikes
may have to be coated with a less permeable material, such as spray-applied
epoxy resin. Diked areas should be equipped with manual release valves,
siphons, or pumps to permit removal of collected liquids. Valves should be
chained and locked in a closed position when not in use. Any liquids in a
tank or in ancillary equipment that do drain to a secondary containment system
should be removed within 24 hours in order to minimize risks to the
environment and to human health.
7.1.2.1.5 Adequate Capacity
The requirement of.Section 264.193(b)(5) is that a secondary containment
system be designed and/or operated to hold 110 percent of the design capacity
of the largest tank within the containment area. This allows a significant
-------
7-23
o>
3
O1
o
f>
o
o
z
o c
-------
7-24
margin of safety for release containment, since most releases will be less
than the amount contained in a full tank. Note that the Section 264.193(b)(5)
secondary containment requirement applies to liners and vaults, but not to
double-walled tanks.
The capacity of a diked area is calculated by multiplying the containment
surface area, less the tank base area, by the height of a dike. Depending on
tank volume, additional freeboard may be required to contain the surge and
waves from a sudden, catastrophic tank failure. The dike designer must
determine the necessary additional freeboard for this situation, bearing in
mind that low viscosity liquids, Heavy gases, and cryogenic mate" a1 s
generally require higher dike walls.
7.1.2.1.6 Excess Capacity
To prevent overflow of a secondary containment system, Section
264.193(b)(6) requires that:
o the containment be designed or operated to prevent run-on and
infiltration of precipitation into the retaining area, or
o the containment be designed with an excess capacity sufficient
to hold precipitation from a 25 year, 24 hour storm, in
addition to the capacity required in Section 264.193(b)(5).
The calculation of maximum precipitation quantity from a 25 year, 24 hour
storm is the depth of incident precipitation expected (from local
meterological data), multiplied by the area draining into the secondary
containment.
A tank system can prevent run-on and infiltration from entering a
secondary containment area by having diversion dikes or ditches, curbs on
paved areas, or interceptor ditches on open land, in order to divert run-on
away from the system. An impermeable cover on the ground over an underground
secondary containment system and/or a slope down away from the tank will
-------
7-25
further reduce run-on and infiltration into the containment area. An
underground tank system is advised to have, in-addition, liner upper edges
folded inward towards the tank (liner turnback, see Figure 7-4) or a vault
with a waterproof outer coating on the concrete. A double-walled tank, if
structurally secure, is sufficient to prevent run-on and infiltration of
precipitation into its secondary containment area.
The Section 264.193(b)(6) regulations note that if precipitation
inadvertently infiltrating into a secondary containment system becomes
contaminated and is a hazardous waste under 40 CFR 261, the waste is subject
to hazardous waste management practices, as defined in 40 CFR 262-265. If the
material is discharged through a point source to U.S. waters, it is subject to
Sections 307 and 402 of the Clean Water Act, as amended. Accumulated liauid
in a secondary containment system should thus be monitored for contamination
by wastes.
7.1.3 Citation: Types of Secondary Containment
A description of the required secondary containment for aboveground,
inground, and underground tanks must include one of the following devices:
(1) a liner external to the tank (Figures 7-4, 7-5), (2) a vault (Figure 7-6),
(3) a double-walled tank (Figure 7-7, 7-8), or (4) an equal device approved by
the Regional Administrator, as specified in Section 264.193(c)(1-4). Both
liners and vaults may have one or more tanks located within the secondary
con-tainment area. Guidance to achieve the Section 264.193(c) standards is
discussed throughout this chapter (7.0), wherever additional regulatory
performance requirements for these containment devices are cited.
7.1.4 Citation: Liner Requirements
Sections 7.1.4, 7.1.5, and 7.1.6 of this document cite the specific
regulatory requirements for each type of tank secondary containment. The
specifications for a tank excavation liner, as stated in Section
264.193(d)(l), are as follows:
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7-26
O)
UJ
z
<
a:
m
S
UJ
LU
CO
ES
o
-------
7-27
IT)
I
V
cn
-------
7-28
I.
3
CD
re
c
.x
01
r
c.
-------
7-20
Figure 7-7
Sampling
Standplpe
or
Electronic
Liquid
Detection
Exterior Protection:
Coel-ter epojy with
eacrlflclal anodet; or
-FRP Coating
DOUBLE-WALLED STEEL TANK
Interstitial Space
May not bepreaent for electronic monitoring
4
DOUBLE-WALLED FRP TANK
DOUBLE-WALLED 1
CONFIGURATION
-------
7-30
Figure 7-8
INTERSTITIAL SPACE
(MONITORED FOR
VACUUM,PRESSURE,
VAPOR OR LIQUID)
SHELL SPACER
INNER WALL
SHELL SPACER
COATING TO
PROVIDE CORROSION
PROTECTION FOR
EXTERNAL WALL
OUTER WALL
(DRAWN TO APPROXIMATE SCALE)
CROSS SECTIONAL VIEW
-------
7-31
"(i) Free of cracks or gaps; and
(ii) Installed to cover all surrounding earth likely to come
into contact with the waste if released from the tank(s)
(i.e., capable of preventing lateral as well as vertical
migration of the waste)."
7.1.4.1 Guidance to Achieve the Part 254 Standard
Liners external to tanks may be used to contain aboveground, inoround,
and underground tanks. Diking and curbing around an aboveground tank should
be used in conjunction with a liner to contain any released material (see
Figure 7-5). Typical earthen dike construction is illustrated in Figure 7-9.
A liner must provide a complete "envelope," preventing both lateral and
vertical migration of released material. Care must be taken to ensure that a
leak proof connection is made between tank and piping containment systems (see
Figure 7-10).
A lined excavation must have a watertight cover extending at least one
foot beyond each side of the. excavation in order to prevent precipitation
infiltration. The cover may be constructed of asphalt, reinforced concrete,
or a similar material that provides protection from traffic. The cover should
be sloped to drainways leading away from the storage excavation. The only
openings in the cover should be those required for tank access and leak
detection equipment. These openings must be protected with watertight caps.
The materials that are satisfactory to EPA for the construction of
secondary containment liners are clay and synthetic flexible membranes. Other
materials, such as bentonites, soil cement, and asphalt can be used, if they
meet the impermeability and durability (for the life of a tank) performance
standards for an excavation liner. Generally, clay under good environmental
conditions and synthetic membranes are likely to have the longest reliable
services 1ives.
-------
-------
7-32
Fioure 7-9
Typical Earthen Dike Construction
be added)
-------
7-34
The selection of an appropriate liner material depends on site geologic
characteristics, waste stored, climate, and cost. The durability of a
material, particularly a synthetic flexible membrane material, depends
principally on proper installation (avoiding punctures from rocks, debris,
etc.) and waste compatibility with the liner. Any liner material selected
must be able to prevent releases for the lifetime of the tank it is
enclosing. The different liner materials may be used together, for added
protection against releases to the environment. For example, soil cement can
serve as a base for a synthetic membrane liner to protect the membrane. The
liner should have a minimum slope of I/A inch per linear foot to a dry well or
a collection sump to allow liquids to drain for detection and removal. Liner
materials are described below.
7.1.4.1.1 Clay
Because of its general availability in many areas and its low cost, clay
is often considered the first choice for a secondary containment liner. If
the material has a permeability rate of approximately 10" cm/sec or lower
and is installed properly, such a liner generally will provide a suitable
barrier aaainst leakaae from a tank release.
Clay varies in composition and permeability and is subject to drying,
cracking, and destabil ization when exposed to some organic solvents. If a
clay liner is not kept moist, usually by a soil cover, shrinkage cracks may
form. Clay may also be permeable to some materials, particularly after
exposure to water. Furthermore, installation of clay liners can be extremely
complex, as it depends heavily on the characteristics of a site and of the
clay. The selection of a clay material for a particular liner application
should be based on tests for suitability, performed by a soils enqineer or a
soils chemist.
To be adequately designed to prevent releases, an excavation must be free
of water, and a clay liner must be sufficiently thick, sufficiently plastic*
well-compacted, and installed at the proper moisture content. Clay liners are
-------
7-35
not normally suitable for use in high ground water areas. A regular cycle of
very wet and dry seasons may make a clay liner ineffective.
7.1.4.1.2 Synthetic Flexible Membranes
Synthetic flexible membrane liners (FML) are composed of polymeric
materials in sheet form. These materials represent a wide variety of
polymers, such as polyvinyl chloride (PVC), polyethylene, polyester, butyl
rubber, epichlorohydrin, and neoprene. The appropriate liner material should
be selected on the basis of compatibility of the material with a stored
substance, durability, permeability, and the material's ability to resist
damage during installation. Synthetic membranes generally have a hiqh
resistance to bacterial deterioration and chemical attack. The membrane
sometimes will, however, fail under heavy loading.
Efforts should be made during and after liner installation to protect the
material from punctures and tears. Rocks, rubble, and debris must be removed
prior to and during base and wall compaction, in preparation for liner
installation. Protective layers above and below a synthetic membrane will
protect it from punctures and promote drainage.
Synthetic membranes are often prone to cracking at low temperatures and
stretching and distortion at very high temperatures. Liner seams and joints
must be properly sealed to prevent gaps in the synthetic material from which
released waste may enter the ground environment. Sealants must be compatible
with the waste(s) contained in the tank. Furthermore, synthetic membranes
need to be protected from sunlight and ozone by a covering, a particularly
important consideration for an aboveground membrane. A qualified installation
contractor should supervise the synthetic membrane liner installation process
to ensure that all necessary quality control measures are implemented.
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7-36
Two references, National Sanitation Foundation's (Ann Arbor, MI) Standard
54, "Flexible Membrane Liners" (1983) and EPA's Municipal Environmental
Research Laboratory "Expected Life of Synthetic Liners and Caps" (1983)
provide information on and comparisons of the various types of synthetic
flexible membranes. The issue of service life is discussed in both
publications. The EPA report states:
"Selection of the most appropriate liner for a given
waste/environment situation, specifically one that will provide the
longest service lifetime, is a difficult task. Available data on
liner specifications and properties (both on virgin and exposed
samples) do not provide a clear basis for choice though they can
eliminate some materials for a given site or design,...The best
approach to maximum serviceability and durability, economics aside,
seems to be to select the thickest and stronqest FML of a polymer
type consistent with desired chemical resistance and other
site-specific requirements."
EPA's recommended method 9090, printed in the Federal Register Vol. 49, No.
199, p. 38786 ff. describes a compatibility test for wastes and membrane
liners. 4
7.1.4.1.3 Bentonites
Bentonites are naturally occurring inorganic swelling clays that are
usually chemically treated. Mixtures of soils and chemically treated
bentonites may be used to line excavations for underground tanks. Bentonites
have features similar to natural day, but bentonites swell when wet to
produce self-sealing properties. Bentonites may be subject to destabilization
when placed in contact with organic solvents.
The following installation considerations can help prevent the formation
of cracks and gaps in a bentonite layer:
0 An excavation must be drained, stabilized, and not located in
an area of high ground water.
0 A bentonite mixture must be wetted to saturation and compacted
with a steel rolling wheel.
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7-37
0 Water used to wet soil during installation must not have a high
concentration of dissolved salts.
0 Bentonite layer installation must be performed during dry
weather.
0 Soil chemists or soil engineers should be present during
construction to ensure that the correct water, soil, and clay
mixtures and the correct saturation schedules are used.
0 Only a qualified installation contractor should be used to
construct a bentonite containment system.
7.1.4.1.4 Soil Cement
Soil cement is a compacted mixture of Portland cement, water, and
selected in-place soils. The result is a low compressive strength concrete
with greater stability than native soils. A soil cement liner generally will
have medium to low permeability, depending on the soil used. Since
permeabilities vary, a smooth soil mixture is preferred since it produces a
more impermeable structure. Excessive cement in the mixture, however, can
lead to shrinkage cracks. ,
As A rule, soil cement is more permeable than bentonites, clays, or
synthetic membranes. Soil cement is durable and resists aging and weathering,
but degrades rapidly with high frost penetration. In an area with high ground
water, soil cement is an inadequate tank excavation liner.
To prevent the formation of cracks and gaps, soil cement should be
appropriately moistened to prevent the liner from drying too quickly. A soil
cement liner must be stiff enough to avoid slippage on excavation walls, but
plastic enough to consolidate well. Lastly, soil cement must be cured
properly for maximum structural integrity.
7.1.4.1.5 Asphalt
Asphalt, similar to road-paving material, has good strength, durability,
ana ib relatively impermeable when properly sealed. Certain organics will
-------
7-38
dissolve asphalt, however, so compatibility of a stored waste and the asphalt
must be definitively determined prior to liner installation. Typically,
asphalt is sprayed on a foundation or base as a sealant. Asphalt emulsions
are also used.
7.1.5 Citation: Vault Requirements
A concrete vault system is subject to the following Section 264.193(d)(2)
requirements:
"(i) Constructed as a continuous structure with chemical
resistant water stops in place at all joints (if any);
(ii) Provided with an interior coating that is compatible with
the stored waste for the purpose of preventing migration
of waste throuah the concrete and also an exterior
moisture barrier to prevent migration of moisture into the
vault; and
(iii) Provided with a noncorrosive porous fill material around
the tank if the waste being stored meets the definition of
iqnitable waste under §261 ,,21 of this chapter."
7.1.5.1 Guidance to Achieve the Part 264 Standard
A vault consists of concrete walls and a concrete bottom slab within
which a tank is placed. A vault usually includes a cover. When the concrete
is coated with an impermeable material, the vault will be able to contain
leaks from the tank and provide protection from potentially corrosive soil.
Generally, vaults are most effective when the tank(s) within them are
supported on cradles or saddles. This design allows the tank(s) to be
thoroughly inspected and repaired on all sides from within the vault. Figure
7-6 shows two tanks on cradles in a vault. The longer a tank 1s, the more
cradles or saddles are needed. Cradles or saddles should support at least
120° of a tank's circumference. Contact should ideally consist of a metal
reinforcino wear plate, hermetically sealed to a tank, and a metal saddle,
-------
7-39
both resting on a concrete pier. Alternatively, although it is a less
desirable design, a metal plate may be sealed to the tank, resting directly on
the concrete saddle. Under no circumstances should the wear plate consist of
decomposable material such as tar-saturated felt paper because this moist
surface can encourage corrosion.
In addition to ease of inspection and repair, early warning and material
recovery are facilitated in a vault without backfill. Some vaults are filled
with appropriate bedding and backfill material (e.g., sand) to provide
structural support for the contained tank(s) and to protect against ignition
of ignitable materials. When a tank is storing ignitable hazardous material,
local fire codes and Section 264.193(d)(2)(iii) routinely require the interior
vault space to be filled with an inert backfill material. To ensure that
flammable vapors, if any, are detected and relieved in a vault without
backfill, the vault should be properly vented. As an additional safety
measure, prior to entering a vault for inspection, a fan or pump may be used
to evacuate vapors. A vapor detection probe in the vent line can also serve
as an early warning of liauid release.
Figure 7-11 shows a schematic, cross-sectional view of waterproofing at a
vault's base corner, detailing the water stop required in Section
264.193(d)(2)(i). Water stops must be chemically compatible with the waste(s)
in a vault. A vault should contain no top connections other than entry
manholes and other top openings for piping, vents, monitoring devices, etc.
All vault openings require waterproof seals. The floor of a vault should be
constructed with a slope (typically greater than or equal to 1/8 inch vertical
per foot horizontal) that channels any leaked or spilled waste to a collection
area.
Concrete is one of the most common construction materials for a vault.
Because concrete is porous and cracking is inevitable, the interior of a vault
must be lined with an impermeable barrier to prevent releases to the environ-
ment. To minimize cracking, the barrier's thermal expansion coefficient
-------
7-40
Figure 7-11
Waterproofing at Vault Base Corner
Concrete Caat
:Waterproofing farrier
-------
7-41
should be similar to that of concrete (in areas of temperature extremes) and
the barrier should have a low modulus of elasticity to prevent barrier
stresses from being greater than the tensile strength of the concrete, over
the temperature range expected during use. Cracks in concrete may occur
during curing shrinkage of two-component polymeric materials.
Selection of an impermeable barrier material for a concrete vault
requires compatibility of the material with the stored waste and
impermeability to the waste. These characteristics may be temperature
dependent (see pp. for more information on compatibility). Table 7-4
summarizes general characteristics of barrier systems. The permit applicant
must be able to demonstrate the chemical compatibility and impermeability of a
concrete vault's barrier material.
Waterproofing the exterior of a concrete vault requires a continuous
membrane that completely encloses the vault. Waterproofing barriers include
hot- and cold-apolied materials such as bituminous-saturated felt or fabric,
glass fabrics, and sheet elasUmers. The thickness or number of plies varies
with the site-specific water table conditions in the environment surrounding a
tank. Waterproofing membranes that are bonded to a tank are preferable over
unbonded materials. Vaults are generally unsuitable in areas of high ground
water because eventually the vault will deteriorate and fill with water.
American Concrete Institute (ACI) Publication 515.1R-79, "A Guide to the Use
of Waterproofing, Dampproofing, Protective and Decorative Barrier Systems for
Concrete" (1984) provides extensive guidance and references on tank coatings,
liners, and waterproofing materials and methods of application.
Constructing a vault from concrete with reinforcing steel provides
additional structural integrity and helps to prevent cracking. Reinforcing
bars (rebars) should be coated to prevent corrosion.
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7-42
Table 7-4
General Categories of Internal Barriers for Concrete
Total
Severity nominal
of chemical thickness
environment range
Mild Under
40 mil
(1 mm!
Intermediate 125 to
375 mil
(3 to 9 mmi
Severe 20 to
250 mil
('/! to 6 mmi
Severe 20 to
280 mil
(V: to 63/« mm)
Over
250 mil
(6 mm)
Typical
protective
barrier systems
Polyvinyl butyral, :>olyurethane,
epoxy, acrylic, chlorinated rubber,
styrene-acrylic copolymer.
Asphalt, coal tar, chlorinated rubber.
epoxy, polyurethane, vmyl, neoprene,
coal Lar epoxy. coa! tar urethane
Sand-filled epoxy, sand-filled poly-
ester, s*id-filled polyurethane, bitu-
minous materials
Glass-reinforced epoxy, glass-re-
inforced polyester, precured neoprene
sheet, plasticized PVC sheet
Composite systems:
la) Sand-filled epoxy system topcoated
with a pigrnented but unfilled
epoxy
(b) Asphalt membrane) covered with
acid-proof brick using a chemical-
resistant mortar
Typical but not
exclusive uses of
protective systems
in order of severity
Protection against deicing salts.
Improve freeze-thaw resistance.*
Prevent staining of concrete.
Use for high-purity water service.
Protect concrete in contact with chemical
solutions having a pH as low as 4, de-
pending on the chemical.
Protect concrete from abrasion and inter-
mittent exposure to dilute acids in chem-
ical, dairy and food processing plants.
Protect concrete tanks and floors during
continuous exposure to dilute mineral,
tpH is below 3l organic acids, salt solu-
tions, strong alkalies.
Protect concrete tanks during continuous
or intermittent immersion, exposure to
water, dilute acids, strong alkalies and
salt solutions.
Protect concrete from concentrated acids
or acid /solvent combinations.
S«* S«lx>ri 3462 belore using i owner lo improve Irttu thiw resisUnce
tOlher membranes may b* used depending on chemiciJ environment
Source: ACI 515.1R-79, p. 29.
Table 7-4 reproduced with permission from the Anerican Concrete Institute.
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7-43
A tank contained within a building may be considered to be within a
vault. If the building, aboveground or inground (e.g., with a basement
structure), is waterproof and the tank is situated on an impermeable floor
with leak detection and collection mechanisms in place, the structure will
meet the vault requirements of Section 264.193(d)(2).
7.1.6 Citation: Double-Walled Tank Requirements
Double-walled tanks must be designed in the following manner, according
to Section 264.193(d)(3):
"(i) Designed as an integral structure (i.e., an inner tank
with an outer shell) so that any release from the inner
tank is contained by the outer shell;
(ii) Protected, if constructed of metal, from both corrosion of
the primary tank interior and of the external surface of
the outer shell; and
(iii) Provided with a built-in leak monitor."
4
7.1.6.1 Guidance to Achieve the Part 264 Standard
A double-walled tank is essentially a tank within a tank (jacket), with a
vacuum or a pressurized space between the inner and outer walls. The Agency
intends for a double-walled tank to have two walls enclosing the tank's entire
perimeter (360°), not just the tank's lower portions.
Guidelines for the design of underground steel double-walled tanks may be
found in the Steel Tank Institute (STI) publication "Standard for Dual Wall
Underground Steel Storage Tanks," though this standard requires only a 300°
double-wall (the top 60° of a tank may be single-walled), rather than the 360°
enclosure required by EPA. Additionally, Underwriters Laboratories, Inc.
(Northbrook, IL) will, for a fee, analyze the structural adequacy of a
double-walled tank design, taking into consideration loading, unusual
stresses, etc.
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7-44
Double-walled tanks generally are made of metal, fiberglass reinforced
plastic (with or without a stone aggregate between the walls), and metal with
a synthetic "wrap" around the outside (see Figure 7-12). A double-walled
metal tank must be protected from corrosion just as a single-walled metal tank
is protected (see Section 5.5), with a coating, cathodic protection, etc.
Epoxies and vinyl esters are commonly sprayed on or applied with a fiberglass
cloth to a metal tank surface. Double-walled fiberglass tanks are becoming
increasingly common because of their corrosion-resistant properties.
Leak detection within the interstitial space of a double-walled tank is
generally based on detection of a loss of vacuum or pressure. Liquid probes
may also be used to detect waste releases or ingress of of groundwater. See
Section 7.1.2.1.3 for more information on interstitial leak detection devices.
Double-walled tanks drastically reduce the likelihood of releases to the
surrounding environment. Manufacturers' installation instructions should be
followed explicitly to ensure tank integrity.
4
7.1.7 Citation: Ancillary Equipment Secondary Containment
Ancillary equipment for a tank must have secondary containment, as
specified in Section 264.193(e):
"Ancillary equipment associated with tanks must be provided wth
secondary containment (e.g., trench, double-walled piping) that meet
the requirements of (a) and (b) of this section."
7.1.7.1 Guidance to Achieve the Part 264 Standard
Section 264.193(e) states that all ancillary equipment associated with a
tank must meet the secondary containment provisions of Sections 264.193(a,
b). Thus, as per Section 264.193(a), the ancillary equipment (piping, pumps,
and valves associated with a specific tank) must be provided with secondary
containment that:
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7-45
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7-46
o prevents releases to soil, ground water, and surface water,
o detects and collect any release?, into the containment area, and
o removes or allows removal of a release within 24 hours.
Section 264.193(b) requires a secondary containment system to have the
following characteristics:
o compatibility and strength,
o foundation integrity,
o leak detection capability,
o adequate drainage,
o adequate capacity, and
o excess capacity.
All aboveground ancillary equipmert must be provided with secondary
containment since the risks of releases from ancillary equipment breakage and
equipment malfunction are not negligible. For ancillary equipment already in
or on the ground, full secondary containment or_ leak testing and a ground
water monitoring program is required. If the underground ancillary equipment
is part of an existing inground or underground tank without, full secondary
containment, then the tank's ground water monitoring program should be
designed to cover the ancillary equipment also. Secondary containment for all
aboveground portions of the ancillary equipment (i.e., partial secondary
containment) must consist of a leak-proof liner base and diking, as per
Sections 264.193(a), (b), and (d)(l).
Containment for pumps and valves, in compliance with Section
264.193(a)(l), can often be provided most efficiently if U is integrated with
a tank's secondary containment. This is not always feasible, however, so a
separate secondary containment system specifically designed for ancillary
equipment may have to be provided. For equipment such as pumps and valves
(see Figure 7-13), a liner and a sump or similar devices, may be used to
collect leaks.
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7-47
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7-48
Leak detection for an ancillary equipment secondary containment system,
as required under Section 264.193(a)(2), may be provided either by integrating
the mechanism used for a tank with that for the ancillary equipment, or by
installing separate sensors. Leak detection sensors (see Section 7.1.2.1.3)
along the lengths of piping enable an owner or operator to detect even
relatively small leaks and ingress of water anywhere in a piping system.
To remove released waste or ingressed water from ancillary equipment
secondary containment, as required by Section 264.193(a)(3), waste transfer
must be stopped. The containment can then be emptied, if aboveground, or
pumped out, if belowground. The point O'r leakage must then be repaired before
waste transfer starts again.
In the following subsections, three types of piping system secondary
containment mechanisms are described and their respective abilities to comply
with the Sections 264.193(a, b) requirements are discussed. The three types
of piping system secondary containment described are lined trenches, concrete
trenches (similar to vaults^, and double-walled piping. EPA does not
prescribe that these particular secondary containment designs be employed
(Section 264.193(c) does not apply to ancillary equipment). Lined trenches
constructed of synthetic materials are, however, usually the most
cost-effective means of secondary containment.
Lined Trenches. Piping trenches can be either covered or open-topped.
Covered trenches are obviously required for underground piping. Covered
trenches have the advantage of not accumulating precipitation and requiring
precipitation management. For a pressure piping system, a trench that is not
covered may not be able to provide containment in case of a pipe rupture. At
a minimum, a spray shield should be mounted over the top half of a pipeline to
prevent pressurized waste from spraying out onto the ground.
Liners for a pipe trench should be constructed of a material similar to
that used to line a tank excavation. Clavs and synthetic membranes can be
used to line a piping trench. The liner material's seams (for synthetic
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7-49
materials) should be sealed to prevent releases, the material must be
compatible with the stored substance, and it must be sufficiently strong to
withstand the stresses of Section 264.193(b)(1) and any additional stresses
from pressurized flow if the pipeline should rupture. No significant stresses
from vehicular traffic should be permitted on piping. Static head and
hydrologic forces on the piping trench liner are apt to be less than on a tank
excavation liner because of the trench's generally shallower depth.
Trench backfill must be carefully compacted to provide the necessary
support for the line' to prevent failure from settlement, compression, or
uplift. The piping trench should be sloped appropriately so that liquid
accumulates in a location from which it can be withdrawn. The piping trench
must be designed to contain 110 percent of the pipeline capacity, plus
additional capacity for precipitation from a 25 year, 24 hour storm.
Concrete Trenches. Concrete trenches are similar to lined trenches in
design principle, but they are much stronger structurally. A greater amount
of stress .may be placed on tht exterior of a concrete trench than on a lined
trench. Larger loads may be placed on top of a concrete trench than a lined
trench. When clad outside with an impermeable coating, a concrete trench is
able to resist the infiltration of ground moisture. The concrete piping
trench, like a concrete vault, must be similarly compatible with stored
waste.
Concrete, however, is subject to cracking from frost. Because of the
relatively shallow depth of most tank ancillary equipment, cracking may occur
during heavy frost. Thus, concrete trenches may allow releases to enter the
environment in some areas; concrete trenches would be inappropriate in these
locales.
Double-walled Piping. Double-walled piping refers to both piping that
is factory built with two walls and pipe-within-a-pipe applications assembled
on-site. Factory built piping may allow pressurization of the interstitial
space between the two walls, permitting monitoring "tor leaks using pressure
readinas (see Section 7.1.2.1.3).
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7-50
Double-walled piping is equally applicable aboveground or belowqround,
but additional corrosion protection measures may be required belowground. No
precipitation management is required for double-walled piping. Compatibility
of the materials of construction with the stored substance is a concern
because of the possibility of a release into the containment. Backfill for
underground double-walled piping must be placed and compacted as per
manufacturers' instructions for proper support. A cross-section of
double-walled piping with two contained pipelines is shown in Figure 7-14.
7.2 Major Issue Points
1. Is full secondary containment or the ground water monitoring
alternative (partial secondary containment or leak testing and a
ground water monitoring program) to be implemented at an existing
tank facility?
2. What is the most practical, effective secondary containment design
for each tank, i.e., a liner, a vault, a double-walled tank, or an
equivalent device (as approved by the Regional Administrator)?
3. Does the selected secondary containment prevent release migration,
detect and collect releases, and permit removal of collected
releases and incident precipitation?
4. Does the selected secondary containment meet the six Section
264.193(b) design requirements which apply to all containment
systems?
5. Are the design and installation requirements specific to each type
of tank secondary containment (Sections 264.193(d)) being met?
6. Is the ancillary equipment secondary containment properly designed,
installed, and integrated with the tank's containment if "cc',.:b^2?
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7-51
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8.0 TANK SYSTEMS NOT IN COMPLIANCE
WITH THE SECONDARY CONTAINMENT REQUIREMENTS
8.1.1 EXISTING TANK SYSTEM ALTERNATIVES TO FULL SECONDARY CONTAINMENT
REQUIREMENT?
Regulatory Citation
264.193(f). As an alternative to complying with the full secondary
containment requirements, the owner or operator of existing tank system(s)
(excluding aboveground tank(s) that are situated in such a manner that the
bottom of the tank is above the plane of ground level) may implement a ground
water monitoring program and must also install partial secondary containment
for any aboveground portions of the tank system. This ground water monitoring
alternative can not be used for those systems used to treat or store EPA
hazardous waste numbers F020, F021, F022, F023, F026 or F027 (refer to
Appendix A for definitions of these wastes).
$270.16(h) - Specific Part B 1nformation requirements for tank
systems. Owners and operators of facilities that use tanks to store or treat
hazardous waste must provide the following additional information:
(h) for tank systems not in compliance with the secondary containment
requirements of §264.193:
(1) all plans, reports and other information required under
5270.l*(c); and
(2) detailed plans and descriptions of the partial secondary
containment system for aboveground portions of the tank
system(s).
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8-2
8.1.1.1 Guidance to Achieve the Part 264 Standard
52 64.193 (f). Owners and operators of existing tank systems may
provide a ground water (saturated zone) monitoring program, that may be
complemented with a vadose zone (unsaturated) monitoring program, in lieu of
full secondary containment. The monitoring program is intended for facilities
where it is economically and technically impractical (as approved by the
Regional Administrator) to retrofit full secondary containment around those
portions of existing tanks and ancillary equipment that are already on or
below the ground surface. The around water monitoring program (outlined in
264.193(g)) must be used in conjunction with a partial secondary containment
system (citation 270.16(h) (2}, discussed in Section 7.1 of this document), for
all the aboveground portions of the tank system. In addition to ground water
monitoring, owners and operators must perform semi-annual leak testing for
underground tank systems (see Section 8.1.11) and thorough periodic
assessments of inground and aboveground tanks (see Inspections
Section - Chapter 11).
The purpose of tjie Section 264.193(g) regulations is to provide
long-term protection for the environment by preventing migration of hazardous
constituents from a tank system to the environment during the system's
operating life. Hazardous constituents have been defined as any constituent
listed in Appendix VIII of Part 261 (refer to Appendix ). The operating
life includes a post-closure care period which is designed to minimize the
potential of contaminant migration after closure to adjacent subsurface soils,
ground water and surface water. The ground water monitoring requirements are
intended to ensure that owners or operators detect any ground water
contamination immediately and to implement corrective action at the facility,
if necessary, to protect human health and the environment.
The ground water monitoring program requires the permittee to install
a ground water monitoring network. This network includes wells near tank
system(s), and located: 1) downqradient of the system(s), marking the limit
of the waste management area; and, 2) upgradient of the system(s), providing
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8-3
background water quality samples. The permittee must also compile a list of
all hazardous constituents present in the regulated tank systems. A set of
indicator parameters or constituents, capable of detecting leakage from the
tank system, will then be selected by the Regional Administrator. The
concentrations of these indicator parameters or constituents must routinely be
monitored in the downqradient wells.
This ground water monitoring program, in conjunction with partial
secondary containment, is to be implemented at tank facilities where no
hazardous constituents are known to have migrated to the ground water from the
facility. The proaram is designed to alert the owner/operator when leakage
from the tank system first reaches the ground water so ample time will remain
for corrective action.
If a tank system is found to be leaking, corrective action must be
initiated either by removing the tank system and the contamination responsible
for the violation or by treating the contamination rr\_ sj_tu_. Corrective action
that merely contains the hazardous waste is not acceptable. Containment
measures designed to prev«nt migration by creating barriers or by modifying
gradients may, however, assist removal or treatment systems (see Section 12).
8.1.2 GROUNPHATER MONITORING AND PARTIAL SECONDARY CONTAINMENT REQUIREMENTS
Regulatory Citation
264.193(g)(1). The ground-water monitoring requirements apply to
owners/operators of existing tank systems that do not have full secondary
containment. Owners/operators must install a ground water monitoring system
at a compliance point to be specified in the permit by the Regional
Administrator.
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8.1.2.1 Guidance to Achieve the Part 264 Standard
Compliance Point (26*.193(g)(1)(i)). The intent of this section is to
discuss the implementation of a detection monitoring program for tank systems
at hazardous waste facilities. It is important that no hazardous constituents
are known to have migrated from a tank system to the ground water beforehand,
since the purpose of this program is to alert the owner/operator when
contaminants from the tank system first reach the ground water.
The monitoring network includes downgradient wells that extend into
the uppermost aquifer at the limit of a waste management area (the compliance
point) and upgradient wells that provide samples representative of background
water quality in the vicinity of a tank system. The information that must be
submitted includes:
1) A map describing the "limits of the waste management area" that
delineates the perimeter of the facility. If the facility
contains more than one tank system, this area must ''-^ude all
tanks and ancillary equipment, such as pipes, dikes, _L ^s, etc.
2} The waste characteristics and their emplacement within the
facility.
3) The site-specific hydrogeologic setting including the ground
water flow direction and the upper boundary and thickness of the
uppermost aquifer.
Refer to Figure 8-1 for a site schematic indicating a typical waste management
area and the compliance point. The compliance point is typically not a single
point because it contains several spatially separated wells.
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FIGURE 8-1
Site Schematic Indicating a Typical Watte
Management Area and the Compliance Point.
Uppermost Aquifer
Compliance
S- Point
Lhnrt of
Waete Management Area
Medium Grained
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8-6
Waste Management Area (264.193(g)(1 )(ii)). The waste management area
is the limit projected in the horizontal plane of the area covered by the tank
system. The waste management area includes any horizontal space taken up by
the tank or any ancillary equipment connected to the tank.
More Than One Tank (?6d.193(g)(1)(iii)). If a facility contains more
than one regulated tank, the waste management area is described by an
imaginary line circumscribing the several regulated tanks. For facilities
having widely spaced tanks, the waste management area should be evaluated as
shown in Figure 8-2. Compliance point monitoring wells should be located on
the downgradient side of the regulated tank systems, in this case. If the
downgradient portion of a waste management area is broad, there might be a
compliance "region" rather than a compliance point, with several downqradient
we!Is.
For very widely spaced tanks, a ground water divide may occur between
tanks. In this setting, the procedure for circumscribing the regulated units
is useless. Here, the compliance point locations should be based on the
ground water flow direction at each regulated tank system. (Figure 8-3)
8.1.3 INDICATORS/WASTE CONSTITUENTS THAT ARE REQUIRED TO BE MONITORED -AS
DETERMINED BY THE REGIONAL ADMINISTRATOR
Regulatory Citations:
264.193(g)(2). "The owner or operator must monitor for indicator
parameters (e.g., specific conductance, total organic carbon, or total organic
halogen) waste constituents, or reaction products that provide a reliable
indicator of the presence of hazardous constituents in ground water. The
Regional Administrator will specify the indicators or constituents to be
monitored in the facility permit."
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8-7
FIGURE 8-2
Compliance Point Monitoring for
Facilities Having Widely Spaced Tanks
Ground Water Flow Direction
Waste Management Ares
Monitoring Well
Oround Water
Flo« Direction
Wwto
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8-9
8.1.3.1 Guidance to Achieve Part 264 Standard
The Types, Quantities and Concentrations of Waste Constituents
(264.193(g)(2) (i)_). The most comprehensive approach to monitoring ground
water quality is to list all the Appendix VIII constituents that could
potentially leak and migrate from the tank system to ground water. This can
be accomplished by requiring the applicant to identify those Appendix VIII
constituents that can reasonably be expected to be in the wastes contained in
the tank systems and those that can be derived or formed as products of
reactions in the geologic materials below the tank systems. Concentration
limits for each constituent can subsequently be established, based on
background, upgradient well concentrations. Once it has been established what
types, quantities and concentrations of wastes are contained in or can be
derived from a tank system, the Regional Administrator will specify the
indicators or constituents to be monitored in the facility permit.
The Vadose (Unsaturated) Zone (26d.193(g)(2)(11)). The vadose (or
unsaturated) zone is the ground layer beneath the topsoil and overlying the
water table in which water in pore spaces coexists with air, or in which the
geological matte*- is unsaturated. The term "vadose zone" is preferable to the
often used term "unsaturated zone" because saturated regions are frequently
present in vadose zones.
The agency is currently in/estigating alternate means for monitoring
hazardous waste facilities, particularly those sites where ground water
monitoring would either not detect migration of contamination at all (e.g.
regions with extremely deep ground water tables), or detect it only after
significant soil contamination may have occured. In such cases, monitoring of
the vadose zone would be advised to compliment a limited ground water
program.
Soil and materials of the vadose zone may have a significant, but
sometimes temporary, capacity to remove or retain a limited quantity of
contaminants from downward percolating water. The extent of ground water
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8-10
contamination due to waste percolation also depends strongly on the rate and
volume of recharged water. In the typical semi-arid climates of the west,
contaminants may be retained above the ground water in a nearly permanent
condition. For example, Runnells (1976) demonstrated that soil from Sulfur
Spring, New Mexico, has an enormous capacity to remove copper from mill
water. The additional observation that copper removal is irreversible
indicates that thousands of years are required before ground water (located at
about 100 feet depth) at the site will be affected. By contrast, in the more
humid areas of the east, contaminants may be rapidly carried downward to the
water table.
In genera1, characterization of soils complements the ground water
investigation by identifying the local lithology and estimating the extent and
thickness for (possible) vadose zone subsurface contamination. Typically, the
soils investigation addresses the characterization of the shallow unsaturated
subsurface down to the saturated zone.
The objectives of the soil characterization procedures are as follows:
o increase available data on local lithology,
o delineate thickness and extent of the soil strata,
o determine geophysical characteristics of the shallow
subsurface, and
o determine contaminant retardation characteristics of the
soil (e.g., field capacity, adsorption, ion exchange, etc.).
Determination of Soil Contamination. Sampling in the vadose zone may
be desirable where:
o It is suspected that hazardous chemicals may have percolated
through the zone.
o Unusual hydroaeologic conditions exist that can prohibit
downward percolation of contaminants (e.g., faults or
discontinuous clay layers).
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8-11
o Evaluation of adsorption and attenuation of contaminants in
the soil is a critical factor.
o The ground water table is very deep.
At tank sites, contaminants may exist essentially within shallow
subsurface soils, without percolating downward to the ground water. For
example, one area that would be of concern is a downgradient wet area in the
immediate vicinity of a tank site. Under these conditions, contaminants may
be slowly migratinq from this soil zone. Another instance of contaminant
non-percolation would occur if contaminants are trapped in pockets or perched
on low permeability soil layers directly beneath or immediately downgradient
from a tank site.
Vadose zone monitoring is not a panacea for all hydrogeologic
conditions and. tank system operations. The need for and extent of such
monitoring should be tailored to site specific conditions. For example, if
the wate>- table at a given site is relatively shallow, say within 10 feet of
the land surface, vadose zone monitoring may be minimal. Similarly, if the
vadose zone consists of fractured media, flow occurs primarily in channels,
and the interactions of the vadose zone and waterborne pollutants may be
minimal .
The Regional Administrator may request the placement of lysimeters or
other vadose zone detection devices to monitor the contaminants (see Figures
8-4 8-6).
The objectives of vadose zone monitoring are:
o To determine the characteristics of the soi'1-pore liauid and
the chemical make-up of the soil below the upper soil zone,
and
o To evaluate the capa:ity of the soil to attenuate the
contaminant.
o To detect contaminants prior to their migration to ground
water.
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8-12
FIGURE 8-4
Typical Lysimeter
Profit*
Rubbar Stopper Cap
6 In. Diameter Nominal Boring
1V2ln. Diameter PVC Lytlmatar
with a Poroua Caramle
Sampling Cup
Grade Sand and Natural Matarlal
Slurry Packed Around Poroua Cap
Backfill with Natlva Soil
8 Inch Bantonlta Plug
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8-13
FIGURE 8-5
Detection Monitoring Syttoms for Underground Storage Tanks
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8-14
FIGURE 8-6
Simulating the Detection of a Leaking Underground Storage Tank
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8-15
Contaminants In Ground Water (264.193(g)(2)(iii). Once leakage from a
tank system is suspected following measurement of statistically significant
increase(s) in the concentrations of a hazardous constituent at the compliance
point, the owner/operator of a facility will be required to sample the around
water to determine the concentration of the constituents contained in the
abbreviated Appendix VIII list that has been established for the facility.
The Regional Administrator will require the applicant to verify that
appropriate sampling and analytical procedures have been used to obtain this
information. These procedures will be specified in the permit establishing
the detection monitoring program.
In rare instances, the data obtained by using the procedures and
monitoring networks originally specified in the permit may be inadequate.
These instances are most likely to result from changing conditions at the site
that render the oriainally specified monitoring network and/or sampling and
analysis procedures obsolete. These conditions may include a change in the
hydraulic gradient at the site or a change in the type of wastes
accepted/generated at the facility. Several of the situations identified and
discussed in Section 8.1.4.1 (26*-.193(g)(3)) may also result in changing
conditions at the site. These instances might require modifyina the existing
detection monitoring program.
If the data originally submitted for identifying the Appendix VIII
constituents in the ground water are suspected to be inadequate, the permit
writer may require the owner/operator to collect and submit additional data by
using other more appropriate sampling and analytical procedures or modified
monitoring networks.
Background Ground Water Concentration Limits (264.193(g)(2) (1v)). A
concentration limit must be specified for each hazardous constituent listed in
the facility permit. The criteria specified by the regulations for
establishing these concentrations have been designed to implement the Agency's
policy of allowing no degradation of water quality (ground or surface).
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8-16
The establishment of concentration limits for the hazardous
constituents contained in or derived from a tank system will reauire
determination of background levels for these constituents. This will reauire
collection of background water quality data and interpretation of that data in
order to establish background levels. Concentration limits for the ground
water at the compliance point will be established as the background water
level concentrations. Any degradation beyond background ground water quality
will indicate that the regulated tank systems are leaking or have leaked.
8.1.4 GROUND WATER MONITORING SYSTEM REQUIREMENTS
Regulatory Citation
264.J93(g)(3). The ground water monitoring system must consist of a
sufficient number of wells, installed at appropriate locations and depths to
yield representative ground water samples from the uppermost aquifer that:
o Represent the quality of background water that has not been
affected by leakage from a tank system; and
o Represent the quality of ground water passing through the
compl iance point.
8.1.4.1 Guidance to Achieve Part 264 Standard
264.193(g)(3)(i)(A). All monitoring wells must be cased in a manner
that maintains the integrity of the monitoring well bore hole. This casing
must be screened or perforated and packed with gravel or sand, where
necessary, to enable collection of ground water samples. The annular space
(i.e., the space between the bore hole and well casing) above the sampling
depth must be sealed to prevent contamination of samples and the ground
water.
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8-17
The guidance for representing the background ground water quality
unaffected by tank leakage and the special considerations of the permit
writer, such as:
o water-table mounds,
o seasonable variation in ground water flow directions,
o nearby ground water punpinq,
o tidal effects,
o insufficient on-site area for any background monitoring,
o facilities containinq dense immiscible fluids, and
o the procedures for establishing background levels;
can be obtained by reviewing sections 3.4 and 7.3 in the RCRA Permit Writer's
Manual - Ground-Water Protection, 4Q CFR Part ?64, Subpart F.
264.193(g)(3)(i)(B). The guidance for representing the quality of
ground water passing through the compliance point and the special
considerations of the permit writer, such as:
o facilities containing dense immiscible fluids,
o partially-used waste management area,
o stratified aquifers, and
o identifying hazardous constituents derived from the tank system,
can be obtained by reviewing sections 3.5 and 7.2 in the RCRA Permit Writer's
Manual - Ground Water Protection, 40 CFR Part 264, Subpart F.
264.193(g)(3)(ii). If a facility contains more than one tank system,
separate ground water monitoring systems are not required for each tank system
provided that provisions for sampling the ground water In the uppermost
aquifer will enable detection and measurement at the compliance point of
monitoring parameters or constituents that have entered the environment from
the tank systems.
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8-18
264.193(g)(3)(i i i). The guidance for the monitoring well construction
special considerations of the permit writer, such as:
and the special consi
o structural characteristics of casing materials,
o chemical resistance of casing materials,
o sampling interferences introduced by casing and well
materials,
o well diameter,
o well intake design and development,
o determination of the suitability of open hole completions,
o screen and gravel pack design,
o well development,
o sealing the annular space,
o determining the need for a sealant,
o selection of a proper sealant, and
o placement of sealant in the annular space,
can be obtained by reviewing sections 4.2 - 4.5 in the RCRA Permit Writer's
Manual - Ground Water Protection, 40 CFR Part 264, Subpart F.
8.1.5 GROUND WATER SAMPLING AND ANALYSIS PROCEDURES
Regulatory Citation
264.193(g)(3)(iv). The ground water monitoring program must include
consistent sampling and analysis procedures, designed to ensure monitoring
results which provide a reliable indication of ground water quality below the
waste management area and which accurately measure monitoring parameters or
constituents in ground water samples. At a minimum, the program must include
procedures and techniques for:
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8-19
(a) sample collection,
(b) sample preservation and shipment,
(c) analytical procedures, and
(d) chain of custody control.
?64.193(g)(3)(v). The ground water monitoring program must include a
determination of the ground water surface elevation each time ground water is
sampled.
8.1.5.1 Guidance to Achieve Part 264 Standard
264.193(g)(3)(iv & v). The Guidance for ground water sampling and
analysis procedures including such points as:
o sample collection,
o well evacuation procedures,
o sample withdrawal,
o special procedures for immiscible fluids,
o sample preservation and shipment,
o sample containers,
o sample preservation procedures,
o analytical procedures and methods,
o 1 aboratory selection,
o chain of custody,
o sample labels,
o sample seals,
o field log book ,
o chain of custody record,
o sample analysis request sheet,
o laboratory log book, and
o water level measurements
can be obtained by reviewing Chapter 5 in the RCRA Permit Writer's Manual
Ground-Water Protection, 40 CFR Part 264, Subpart F.
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8-20
8.1.6 BACKGROUND DATA REQUIREMENTS FOR EACH OF THE MONITORING PARAMETERS
Regulatory Citation
264.193(g)(4). The owner or operator must establish a background
value for each of the monitoring parameters or constituents specified in the
permit. The permit will specify the background values for each parameter or
specify the procedures to be used to calculate the background values.
8.1.6.1 Guidance to Achieve Part 264 Standard
Sampling Frequency & Number of Samples Required to Establish
Background Ground Water Quality (?64.193(g)(4))(i & iii). Background ground
water quality for a monitoring parameter or constituent must be based on data
from quarterly sampling of wells, upgradient from the waste management area,
for one year. In developing the data base used to determine a background
value for each parameter or constituent, the owner or operator must take a
minimum of four samples from the entire system to determine background ground
water quality, each time the system is sampled. In addition, t^e applicant
should describe the monitoring network, and sampling and analysis procedures
used to obtain ground water quality data.
After specifying the monitoring parameters that require measurement,
the permit writer must also specify in the draft facility permit background
values for these parameters (or procedures to be used to calculate background
values) and the statistical procedures that are to be used when comparing
background values with those measured at the compliance point durino detection
monitoring. Background values are to be expressed in a form suitable for the
determination of statistically significant increases by using the specified
statistical procedure (see Section 8.1.8).
-------
t I
8-21
In some cases, the one year of quarterly sampling data required to
establish background values for detection monitoring parameters may not be
available. In other cases, the data provided by the applicant may be
inadequate. In both situations, procedures must be specified in the permit
for establishing the necessary background values. Sampling and analysis
procedures suitable for establishing background values for each detection
monitoring parameter are also required. The guidance provided In Chapter 5 of
the RCRA Permit Writer's Manual - Ground Water Protection 40 CFR part 264,
Subpart F, should be used when evaluating such procedures.
Background Water Quality Based on Wells that are not Uporadient
(264.193(g )(4) (i i)). Background ground water quality may be based on sampling
of wells that are not upgradient from the waste management area. This
scenario may occur at sites where hydrogeologic conditions make it difficult
for the owner or operator to determine which wells are upgradient. Sampling
at other wells may provide an indication of background ground water quality
that is representative or more representative than that provided by the
(apparent) upgradient wells.
At many sites, the location of background wells may be problematic.
Special attention may be required when waste management areas are located:
o Above water table mounds,
o Above aquifers in which ground water flow directions change
seasonally,
o Above aquifers in which ground water flow directions change
due to tides,
o Close to high yield production wells,
o Close to a property boundary that is in the upgradient
direction, and/or
o Near facilities containing significant amounts of immiscible
contaminants with densities greater than water.
-------
8-22
In these and other situations, the regulations allow the specification
of background wells that may or may not be upgradient. The specification of
background well location and depth in these situations must meet two
requirements: (1) the wells must be located at points least likely to be
contaminated by leaks; and, (2) a procedure for evaluatina whether or not the
background wells are contaminated must be developed.
8.1.7 SEMI-ANNUAL DETERMINATION OF GROUND HATER QUALITY
Regulatory Citation
264.193(g)(5). The owner or operator must determine ground water
quality at each monitoring well at the compliance point at least semi-annually
during the active life of a tank system (including any closure and postclosure
care periods reauired under Section 264.197). The owner or operator must
express the ground water duality at each monitoring well in a form necessary
for the determination of statistically significant changes.
8.1.7.1 Guidance to Achieve the Part 264 Standard
Semi-Annual Ground Water Quality Monitoring (264.193(g)(5). The
Regional Administrator will establish the frequency of routine detection
monitoring in the facility permit. The regulations require that sampling be
conducted at least semi-annually. The Regional Administrator may also
determine that more frequent sampling is needed. A monitoring frequency
should be established that allows sufficient time, should leakage of hazardous
constituents from the tank system be detected, to develop and implement a
corrective action program that protects human health and the environment. The
principal factors that must be considered when establishing sampling frequency
are: the ground water flow rate, the proximity of the facility to ground
water users or sensitive environments, the relative toxicity of hazardous
constituents contained with the waste, and the time required to develop and
implement corrective action measures.
-------
8-23
8.1.8 STATISTICAL PROCEDURES FOR DETERMINING WHETHER BACKGROUND VALUES OR
CONCENTRATION LIMITS HAVE BEEN EXCEEDED
Regulatory Citations
264.193(g)(6). "The owner or operator must determine whether there is
a statistically significant increase over background values for any parameter
or constituent specified in the permit... each time he determines ground-water
quality at the compliance point...
(i) In determining whether a statistically significant increase
has occurred, the owner or operator must compare the
ground-water quality at each monitorinq well at the
compliance point for each parameter or constituent to the
background value for that parameter or constituent...
(ii) The owner operator must determine whether there has been a
statistically significant increase at each monitoring well
at the compliance point within a reasonable time period
after completion of sampling..."
8.1.8.1 Guidance to Achieve Part 264 Standard
264.193(g)(7)(1)(a), (b) & (ii)(a), (b). The regulations specify a
statistical procedure (Cochran's Approximation to the Behrens-Fisher Student's
t-test) to determine if detection monitoring results represent statistically
significance increases over background levels (see Chapter 6 of the RCRA
Permit Writer's Manual - Ground Water Protection). However, in cases where
the background value has a sample coefficient of variation greater than 1.00,
this procedure is not applicable; the applicant must use another statistical
procedure which will be specified in the permit. In addition, even if the
background sample has a coefficient of variation equal to or less than 1.00,
the regulations allow the applicant to propose the use of an equivalent
statistical procedure. The applicant must, however, be able to demonstrate
that the alternative procedure achieves a reasonable balance between the
probability of falsely identifying a non-contaminating tank system and the
probabil ity of failing to identify a contaminating tank system.
-------
8-24
When reviewing any proposed statistical procedures, the permit writer
should refer to the guidance provided in Chapter 6 of the RCRA Permit Writer's
Manual - Ground Water Protection, 40 CFR 264, Subpart F. The permit writer
should review the statistical procedure and underlying assumptions to
determine whether it is applicable to the characteristics of the site's water
quality data. Particular attention should be given to the statistical
distribution of data and the possible primary factors that may be
contributing to the observed variability (i.e., seasonal, spatial, sampling,
or measurement). Although the coefficient of variation may be equal to or
less than 1.00, the statistical procedure specified in the regulation may be
inappropriate for data that s>iows extreme non-normal distribution, pronounced
seasonal or spatial variability, or levels at or below detection limits. In
these cases, an alternative procedure is needed.
A variety of alternative procedures are available, some of which have
been outlined in Chapter 6 of the RCRA Permit Writer's Manual - Ground Water
Protection. Each alternative procedure is applicable only when water Quality
data exhibit specific characteristics. The permit writer should review any
proposed alternative procedure to ensure that the observed characteristics of
the data correspond with those required for the proposed procedure. In
general, any alternative statistical procedure should be applied with the same
level of significance as the standard procedure.
Based on availability of suitable background data, the permit writer
has two options for specifying statistical procedures in the draft facility
permit. If suitable background data is available, the permit writer can
specify a statistical procedure in the facility permit based on the above
discussed factors. However, if suitable background data is not available, the
permit writer may specify the procedure established in Section 264.97(h) (1 )(i)
of the regulations. Should any additional background data indicate that this
procedure is not suitable, the facility's owner/operator must then apply for a
permit modification that would establish a more appropriate statistical
procedure. Alternatively, the permit writer can specify several procedures
-------
8-25
that may be applied depending on c'rcumstances in which each of the procedures
to be used are clearly specified in the draft facility permit. Selection
among the various statistical procedures should be based on the most probable
characteristics for background data at the site.
8.1.9 DETERMINATION OF THE GROUND WATER FLOW RATE IN THE UPPERMOST AQUIFER
Regulatory Citation
Hydrogeoloqic Setting 264.193(g) (8). The guidance for the
determination of the ground water flow rate in the uppermost aquifer can be
obtained by reviewing section 3.3.1 in the RCRA Permit Writer's
Manual - Ground-Water Protection, 40 CFR Part 264, Sub part F.
8.1.10 PROCEDURES FOR REPORTING STATISTICALLY SIGNIFICANT INCREASES FOR
PARAMETERS AT MONITORING WELLS
Regulatory Citation
264.193(g)(9), If the owner or operator determines, pursuant to
paragraph 254.T92(g) (6), that there is a statistically significant increase
for parameters or constituents specified in accordance with 264.193(g)(2), in
any monitoring well at the compliance point, he must:
(i) notify the Regional Administrator of this finding in writing
within seven days. The notification must indicate what
indicators or constituents have been detected; and
(ii) assess the integrity of the tank system in order to
determine the source of the release.
8.1.10.1 Guidance to Achieve Part 264 Standard
Response to a Statistically Significant Increase in Detection
Monitoring Parameter Values (264.193(g)(9)). ..If the comparison between
monitoring parameter values (observed at the compliance point) and established
-------
8-26
background values shows that a statistically signficant increase has occurred,
a tank system is presumed to be leaking. At this time, an owner/operator may
take two actions. He may attempt to show that the statistically significant
increase is (1) due to an error in sampling, analysis, or evaluation or, (2)
due to a source of contamination other than the regulated unit. In such
cases, a program of resampling downgradient wells should be instituted to
demonstrate the source of error, or a program of sampling upgradient wells
should be instituted to establish new background values and verify
contamination from another source, respectively. If these sampling programs
are successful in demonstrating that the statistical increase is not due to
leakage from the tank system, the owner or operator should submit an
application for a permit modification to make any necessary changes in the
detection monitoring program (see Section 8.1.2 of the RCRA Permit Writer's
Manual - Ground Water Protection).
In either case, upon finding a statistically significant increase in
monitoring parameter values, the owner/operator must immediately sample all
monitoring wells to determine the concentration of the constituer* "-stained
in the abbreviated Appendix VIII list that has been establisnea for the
facility. The owner/operator should then notify the Regional Administrator of
these findings.
Consequently, the owner/operator of a facility may find, after
sampling for Appendix VIII constituents in the ground water beneath the
facility, that hazardous constituent values at the compliance point are
identical to background values. It may then be reasonably concluded that
hazardous constituents from the facility are not migrating to ground water.
The facility can then continue operating under the detection monitoring
program.
-------
8-27
8.1.11 SEMI-ANNUAL LEAK TESTING PROGRAM
Regulatory Citation
264.193(h)(U2) All underground tank systems that do not have full
secondary containment that meets the requirements of this section must be leak
tested at least semi -annual ly in accordance with the following:
(1) A leak test of every underground tank to detect any leak
equal to or greater than 0.05 gallon per hou"- and
(2) A leak test of all underground piping to detect any leak
equal to or greater than 0.05 gallon per hour, or a pressure
drop of 5 pounds per inch per minute
8.1.11.1 Guidance to Achieve the Part 264 Standard
The Regional Administrator will establish the frequency for leak
testing an underground tank system that does not have full secondary
containment. The regulations requi-e that leak testing be conducted at least
semi-annual 1 y. The Regional Administrator may determine, however, that more
frequent leak testing is needed.
A leak testing frequency should be established that allows sufficient
time, should a tank system be found to be leaking, to develop and implement a
corrective action program that protects human health and the environment. The
principle factors that are considered when establishing the leak testing
frequency are:
o the ground water flow rate
o the proximity of the facility to ground water users or
sensitive environments
o the relative toxicity of hazardous constituents contained in
the waste, and
-------
8-28
o the time required to develop and implement corrective
actions measures.
See Section 5.1.1.1.1 for more details on leak testing procedures.
8.2 MAJOR ISSUES
-------
9-1
9.0 WAIVER FROM SECONDARY CONTAINMENT
9.1 Regulatory Citation: Waiver f^om Secondary Containment
A hazardous waste sto^aap tank owner or operator who seeks a waiver from
secondary containment reauirements must include various detailed plans and
reports in the Part B permit application. This procedure is specified in:
"270.16H) For tank systems for which an exemption from the requirements
of 66264.193 is soucM ras provided by §264.193(i )1, detailed plans and
engineerina and hydrogeoloaic reports, as appropriate, describing alter-
nate design and operating practices that will, in conjunction with loca-
tion aspects, prevent the miaration of any hazardous constituents into
the o-ou"^ wate" c" s^face wate>~ at anv future time."
The associated Part 264 reauirements are contained in Section 264.193(i).
9.2 Guidance to Achieve the Part 264 Standard
Guidance to achieve the Part 264 standard is self-explanatory in the
Section 264.193(i) regulations which stipulate:
"5264.193M) Except for tanks used to sto»-e or treat EPA Hazardous Waste
Nos. F020, F021, F022, F023, F026, and F027, the owner or operator may be
exempted from all or part of the requirements of this Section if the
Regional Administrator finds, as a result of a demonstration by the owne>-
or operator, that alternative design and operating practices, together
with location characteristics, will prevent the migration of any hazard-
ous waste or hazardous constituents into the ground water or surface
water at any future time.
-------
9-2
In deciding whether to grant an exemption, the Regional Administra-
tor will consider
(1) The nature and Quantity of the wastes;
(2) The p^op^seH aHe^ngte desion and operation;
(3) The hydroqeoloqic setting of the facility, includina the
thickness of soils present between the tank system and
ground water; and
(4) All other factors that would influents the Quality and
mobility of the hazardous constituents and the potential
for them to migrate to ground water or surface water."
For those seekina a waiver from the secondary containment reauirement,
various sections from the Alternate Concentration Limits (ACL) Guidance* will
facilitate preparation of the Part B permit application. In particular
Sectir," j] nf the ArL Guidance manual "Physical and Chemical Characteristics
of the Waste Constituents" will facilitate preparation of "the nature ana
quantity of the wastes" portion of the submittal. Section II of the same
manual "Hydrogeological Characteristics" may provide guidance for the
description of the "hydrogeologic setting of the facility" which must be
provided in the application as well. Various other sections of the manual
might provide information on other factors which affect the Quality of
hazardous elements and their potential to migrate into surface and ground
water. The ACL's guidance details information that is reauired in ACL
demonstrations for RCRA facility permit applicants concerning the
establishment of alternate concentration limits. In order to obtain an ACL
the permit applicant must demonstrate that the hazardous components detected
in the groundwater will not present a substantial threat to human health and
the environment at a given ACL level. This obviously allows for some
migration of hazardous constituents for owners and operators of surface
impoundments, waste piles, land treatment units and landfills, if exposure
*Source:Alternate Concentration Limit Guidance Based on §264.94(b)
Criteria, Part I, Information Required In ACL Demonstrations, "EPA, OSW,
June 1985.
-------
9-3
levels are reduced to levels that are protective of human health and
environment. Most important to note here - regulations for hazardous waste
storage tanks, on the other hand, do not allow for any migration of hazardous
constituents whatsoever. Under these regulations the alternate design and
operation submittal for a waiver to the secondary containment reaui regents
must demonstrate complete prevention of migration of any hazardous constituent
into surface water or around water at any future time.
9.3 Major Issue Prints
Have the followina items been included in the Part B application for
those seeking a waiver from the secondary containment reg'jirement:
(1) The nature and guantitv of the wastes;
(3) The hydrogeologic setting of the facility, including the
thickness of soils present between the tank syste^ and
ground water; and
(4) Any other details on factors that might influence the
miaration of hazardous elements into surface and ground
water .
-------
10-1
10.0 CONTROLS AND PRACTICES TO PREVENT SPILLS AND OVERFILLS
10.1 PrGULATOPY CITATION'S
The inforrBtion reouiren=r,ts for tanls as stipulated in 770.1' ;, 1
the perm't applicant to provide a:
"Description of controls and practices to prevent spills and overflows as
reauirec1 under ?64. l?£(b). "
This inforretion rust be subrritted in a Part B application. These
94(h) standards stipulate that
'ovner? or operators rust use appropriate control? and practice?
,(* "if, r ' c' /-. .-> L'r-i: "c -, *, ; r . :" '. L ;"'":".« f'rr :..--" _ r --
tank systers or secondary containment systers. These include at a
n'ninurr: (1) spill prevention controls such as check valves or dry
disconnect couplinos (?} overfill prevention controls, such as
automatic feed cutoff or bypass to a standby tanV, a"d (3)
reintenance with sufficient freeboard in uncovered tanks to prevent
overtoppinp by wave or wind action or by precipitation. "
Most irportant to note under the new regulations, hoses are reoarded as part
of the tanV system. Therefore when a hose is used to erpty a tank's contents
into a truck, it is subject to these reoin re rents.
Under 2fO?£(h) spills and overflows fror tank systers nvst he
prevented. This reouirenent rejorly encouraoes appropriate controls and
practices to prevent spills during transfer operations or loadinp/unloading of
a tank. FPA' s rajor concern is with releases that occur durinp these
operations, especially at facilities that do not have secondary containment.
10.1.1 Guidance to Achieve the Standards
Spills can occur at both underground and aboveground/in-pround storage
tank facilities because of tank overfilling and drainaoe frorr waste transfer
-------
10-?
hoses. Most of the methods devised for prevention of transfer spills end
overfills are far more prevalent with abovepround tank systerrs, where the
spill is hiphly visible, than with the less visible underground systems. As
the hazards associated with losino waste frorr an underpround systerr becorrp
more and rore apparent, more advanced methods for underpround tanks will he
developed.
Guidance for corplyino with these ?f
-------
10-3
4) Tielng 1n the unloading process with the overfill prevention
systeir 1s recomrended to prevent any unloading frojr taking
place when the overfill prevention systeir 1s non-operative.
?) A bypass prevention systetr m'ght also be included so that the
overfill prevention syster cannot be overriden by the operator.
- -These- el-epw-ts-WiFTiScussef helov.
Level Sensing Devices and Indicators. A variety of devices are available
for detecting liquid levels in bulk storage tanks. Generally, these devices
sense liquid characteristics such as capacitance or therral conductivity or
operate on such comiron principles as buoyancy, differential pressure and
hydrostatic head. Devices which operate based on these corron principles, act
independent of waste flow rate, pressure and temperature.
Specific types of leve"1 sersinc devices for bull' storaoe tani-j c?-1 be
cateprrizeo into the foilor'rc:
1) Float activated devices
2} Capacitance sensors
?) Ultrasonic devices
A) Optical devices
F) Therrel conductivity sensors
F) Pisplacer devices
7) Hydrostatic head sensors
Float activated, capacitance, ultrasoric, optical and therrel
cc'c^rtivity ser-so-i cer, ell ft utilize"' in th-: urYrrr-c:;"' *?-':. <" Tc1^
1P-1 for an overview of their applications. The displaced dev'ces and
hydrostatic head sensors are irore often utilized in aboveground storage
systers. These will be discussed in greater detail in the
abovepround/inground section.
o Float-Activated Devices - Float activated devices are characterized
by a buoyant element that slirply floats on top of the surface of a
liquid. Tape float gauges and float vent valves are corrronly used
types of float-activated devices.
-------
10-4
Table 10-1
Level Petection Devices; for Underground Storape Tanks
Type
Float Actuated Devices
Tape float oaupes
Float vent valves
Copcciian:t c>~ \' ;es
Therrrel conductivity
devices
Dptical devices
Monitor
Liquid Level
Level Indication llarrr and Shutoff Response [1]
Yes
No
Yes
Ye?
Gaupe Interfaces with electronic or
or pneuretic controls
None ^utoratic Shut-off
shutoff electronic controls
Gaupe Audible alarrr and autoretic
electronic controls
T-aupe Audible alarr and autoretic
shutoff electronic controls
-------
10-5
tape float paupe designed for use in underpround pasoline
tanks provides an above-the-tank readout of both gasoline and water
levels while still prohihitinp vapor loss. These can be used for
hazardous liouids as well. See Fioure 10-1 for illustration.
Float vent valves, sp'r^le a-, r
-------
ir-f
Figure 10-1
Tape Float Gaupe for
Underoround Storaoe Tank
OPW 114-DW
The OP* 114-Dw
T«rtk Gape provioes
a *£«: tccu't't
'to OLT o1 cw'- gas
01>ne ilC w»lf 10'
It
escape
ope-jio' mere
i^e ca: anc
if>e sca't tn'Oui;- a
vie* i; p'»ss S^oj'S
ccnoensa'f tp"r cr tie uios'S'3e c1 me 5 ass «
>- c' ft c.r wcei ' ;'?a-
J
aic a-t p>e-ai!.e-iD.e: a i"» ia:'o-) 0-e -.a- is-
PISH' iv lU-Dir, u> ea:' b, u? % P» 'j--s-«:
insujcic-' s'^C'ti as a Qjoe
Mattrialt
Bo:, nafo coit
Cap nar: coa1 a jrr>,
Ga»*eis Duna N
Tape tiee w<"n epoiy pa>ni
OPW 114-SW
Similar lo OPW 114-DW aDOvt CiCCDI il
caiei profluci level only
Source. OPW DivisioaDover Corp
-------
10-7
Fipure 10-?
Ftoat Vent Vatves
for OverfO Prevention
-------
1P-P
Float-actuated devices are imde of a variety of materials, Including
alum'nurr, stainless steel and coated steel, depending upon the
application. These devicese ray be used in conjunction with
pneurretic or electronic devices to operate valves, purrps, rerote
alarr? rr autorBtic shut-o'cf systems.
Capacitance Sensors - These liquid level nrnitorinp devices are
basec1 on the electrical conductivity of fluids. A standard
capacitance sensor consists of a rod electrode positioned vertically
in a vessel with the other electrode usually bein<) the retailic tanV
wall. The electrical capacitance between the electrodes is a
reasure of the height of the interface along the rod electrode. The
rod is usually electrically insulated froir the liauid in the tank by
a coating of plastic.
Capacitance devices are suitable for use Kiln a v,-iCt ronpc o~"
liquids, including the following: petroleum products, such as
gasoline, diesel fuel, jet fuel and no. 6 fuel oil; acids; alkalis;
solvents; and other hazardous liquids. These ray be used in
conjunction with electronic controls to operate purps, valves,
alarrs and other external control systerrs.
Therrel Conductivity Sensors - These devices operate on the
principle of theme! conductivity of fluids. f- typical them?!
condjctivity sensor consists of two terperature-sensitivf prccc-s
connected in a Wheatstone bridge (a type of electrical circuit
configuration.) When the probes are in air or gas, a Trexitruir
tenperature differential exists between the active and reference
sensors, which results In a great tnbalance in the bridge circuit
and a correspondingly high bridge voltage. When the probes are
submerged in a liquid, the tenperature between the sensors is
equalized and the bridge is brought irore nearly Into balance. The
probes my be installed through the side wall of a tank or pipe, or
assenbled together on a self supporting rountino and suspended
t*"rc'JC*" a top connection 01 the tanV.
-------
10-9
conductivity devices ray be used to control level with a
qood decree of accuracy. They ray be used with any liouid
regardless of viscosity or density. They ray also he used with
irrrn'scihle liouid and slurries and in conjunction with electronic
to operate PUTS, valves, ?larr* or other external controls
Ultrasonic Sensors - These devices operate on the principle of
sonic-wave propagation in fluids. A piezoelectric transritter and
receiver separated by a short pap are characteristic of this
device. When the short cap fills with liauid, ultrasonic energy is
transn'tted across to a receiving elerent thereby indicating the
liquid level. These devices can be used in conjunction with
electronic devices to operate punps, valves, alarrs or other
A sonar device is another sonic technique user for level
rreasurerent. A pulsed sound wave, generated by a transm'tting
element, is reflected fror the interface between the liquid and the
vapor-gas rn'xture and returned to the receiver eler^nt. The level
is then r^asured in terrs of the tirre reouired for the sound pulse
to travel fror the transmitter to the vapor/liquid interface and
returr,.
Optical Sensors - Optical sensors operate on the principle of light
refraction in fluids. An optical level rronitorinc syster consists
of a sensor and electronic control devices. An electronic signal is
generated and aimed at the tank rounted sensors which then convert
the electronic signal to a light pulse. This lioht pulse is
trans fritted into the tank by fiber optics, throuph a prisir and out
again via fiber optics. The light pulse is then converted to a
specific electronic signal to indicate the liauid level. A rajor
advance of this syster is that it is self-checking. Any
interruption will set off the alarfr thereby automatically alerting
c"~ in ?r> eouiprt-nt rplfunction.
-------
10-10
Ccrmon applications of an optical sensinp systerr for a tank truck
and bulk storage tank are shown 1n Figure 10-3 and 10-4
respectively. Fssentially the sensor detects the level of liquid in
the tank and transrits the sipnal to the controller device (i.e.
control npnitor) which in turn activates either the shut-off valve
or the level elarr.
Hiph Level Alarre. High level alarrs are essential to a corprehensive
overfill prevention system. Overfill alarrrs can be of either the audible or
visual variety. When rronitorinp several tanks at one tire warninp liphts
should be assipned to each tank to alert the operator as to which tank is
overfillinp.
£u to TO tic Shut-Off Controls. These controls, actinp in conjunction with
Irvc"1 «<";->r dcv;:r!:. rcr-^rr- *v--c.- rpior func*iens: (V r'-evprt t?*~.l'
overfilling ij shuttle off the tani loec'inc pun:- at a preset rsxirur 'MCJU
level; (2) prevent darepe to the tank unloadinp purrp by shuttinp it off at a
low level; and (3) regulate various flow valves to control product flow.
These .control systetrs receive a signal fror the level sensinp device which is
transmitted electrically or pneuretically to the control syster. Pneurretic
devices reouire a repulated supply of clean and dry instrument air, generally
at ?0 pounds per square inch (psi). Flectronic or electric devices generally
reauire 11?V line voltape. [See TaMe 1C-? for characteristics of pneurstic
end electronic control?.]
10.1.1.1. ? Transfer Spill Prevention Systerrs for Underground Tanks
Occurrences of spills during transfer operations can be rriniirized by
using couplings equipped with spring loaded vavles which autoretically block
flow when the hoses are disconnected. Ouick-disconnect couplings equipped
with ball valves and dry-disconnect couplings are conronly used coupling
types. Frerpency shut-off valves right also be installed in the product
transfer line to stop flow of hazardous prodfucts in case of fire.
Applications of these devices will be discussed below. [See Table 10-3 for
-------
10-11
Fioure 10-?
Optical Uquld Level Sensing System For Tank Truck
(O
-Colled C*bl*
Fioure
Optical Liquid Level Sensing System For Bulk Storage System
. Control
Monitor
CoftdvK «u» T»»le»l
-------
10-1?
Table 10-?
CHARACTERISTICS or PNEUMATIC AND ELECTRONIC CONTROLS
f eat ire
Tr£-5- iis 10' cistaic"
S'.i'dj'd trar.s^ i ssior si;-;l
s.,. ' u: t.. : '*".: r .-.<:....< .
Cf '.'- ' kc1*! CI-, :'. ;. .)'..
witn die ltd' ccrp-te'
or data logger
Ree:tior to >ery lo«
temperatures
0?eratio', u Hazardous locations
(e*plcisivt atmosphere;
.WO^C'' ste- cor.pit ibi 1 ity
aid coi' c' riirtc-j-;e
0;t'i'.K". in
Politics (the unmentlone; factor
that frequently pops up)
Li-'ttc to *e. tijnares fee4.
3-1S psi p'a:tically universal
N e-"'-Jt>
Cf-'.', Me- c^ti.'. op-.rjtc ct't
t ic-to-e lectric converters
ec for a' 1 inputs
cr if energize: »itn clear
air
Jn'e'ior unless air Supply IS
completely ory
i.,>;-'.v' - caiici'o (.' s.is'.t"
inexpensive
fair - requires considerable
equipment
L0»t' if ir.St'l ' at lOfi CCS'i J
Slo«:' L^'. aoi^^ctc for r .:;
Suporic" - e'r sjppl>
fo- n:st in;trj-tnis
are reaior.a: ;c
Generally regarded as acceptable but
not the latest thing
Electronic
Practical ly ur liiritei
vanes *Hh manufacturer
N-'- s-ta'.;;'; fp-j'i re:."-c sr^T'c :"-
SuJ-icl U1 S'<; Tc. r . ; {j._ CO'ii'. U
Pri-. j-,;ti: o;:ratc'i .-',- elt:1. . -
pnejT.atlt Converters or e lfcCtrori,yO'1'(!. U
or electri; motor operator reqj're:
Easily arranged »itn minimir
eqjipment
Excellent under usual
condit ions
Superior
Intrinsically safe equipment
available must be removed for
Irft'ior - electrical failure r,;_)
disrupt plant - backup expensive
Superic'
Good - conditioning an: auxi
eqjiD">ert mc-e compatible tc
syste-s approacr.
- beco-ies co-rf.une »l".tiif". - n. rt L'. r i:: 10' o> fa'.
r, 01 stance
Often regarded as the latest and most
modern approach
Source: Anderson, N.A., Instrumentation for Process Measurement and Control, Second Edition, Chilton Book Company,
5601 Chestnut Street, Pni ladelpnia, PA 19139, 1972.
-------
10-1?
Table 10-?
Transfer Spill Prevention Systere
Svs-ter
c ti'or
Spill Control
plications
Ordinary quick.- Product
disconnect coupling Transfer
Quick-disconnect Protect
couplinp equip- transfer
pec1 with hall valve
couplinc
transfer
Frreroency shut-off Flow Control
valves
None
Tank vehicles ant'
storaoe tanks
Built-in valve re- Tank vehicles anc1
duces spills frorr storaoe tanks
disconnect hoses
t'r sr1"''1? frnr Ter.i vericlp? a^r1
nsconncctec hoses storape tanks
/ fusible n^tal
link ratals and
closes the valve
in case of fire
or inpact
For use any place that
in the event of fire,
it is inportant to
stop flow
-------
10-14
Check Valves - Check valves can be used 1n the discharge piping of a purp
or the fill line of a tank to autoratically prevent backflow of a liquid.
Three cormon design tyupes of check valves are: (1) piston or ball check
valves which are typically referred to as lift check valves, (?) tiltinp disk
check valve? ?rd: (?) svinp check valves. Check valves are avail iable in a
wide veriety of size? and raterials of constructior to suit rrst
applications. Cross-sectional views of these types of check valves are shov/n
in Fipures 10-A, 5, 6 and 7. These views portray the various nethods of
preventing backflow.
Coup! inps -When transferring hazardous nateriais fro IT tank to tank,
spills can be prevented by usinp tipht couplinps. Several types of couplings
are available. Selection of coup!inps should be based on terperature,
pressure and the chencal properties of the rreterials beinp transferred. With
V--PK terrrrf* -1 c f r' PT ?r i.Tf s. rr'jr^ircs nj s t he mre securely ettachpd.
The arount c' pressure a coupling can Generally withstanc is usuaViy
determined by the strength of the base -coupling connection. If applied
properly and at average working temperatures: 1) bolt clarrps will handle low
pressure, ?) bands will take low to mediurr pressures, and 3) interlockinp
clarps and swiped or crirped ferrules will handle high pressure. Cherncal
properties of reterials heinp transferred rright also be considered when
selectinp coup! inps, as certain conpounds right in sore cases derape the
coup!ings.
As previcjsly rcntioned in this section, ouick disconnect couplinps are
popular because they are lighter and therefore easier to handle than other
types of couplings. However, when using these types of couplings, additional
treasures nust be taken to prevent spills or loss of waste retraining in the
transfer lines. Ouick disconnect couplings equipped with ball valves can be
used to irinim'ze spills when the hoses are disconnected. However dry
disconnect couplings are best suited for product spill control as they are
equipped with a spring loaded vavle. This spring loaded valve is usually
closed until the coupoing is attached and the valve is rrenually opened with
alever. See Fioure 10-P for a demonstration of the differences between
-------
10-15
Figure 10-4
T>pvs of V
T
Gale \ >J\ c
loK \
flow
Plup Cock
Composed of a tapererd plug with center hold
that fits snupl) into correspondingly shaped
valve seal
Ball Valve
Similar to plug cocks with exception that
the plug is cylindrical
-------
10-16
Flciure 10-F
T>pcs of Vahcs
Anpli VaUc
Similar to globe \al\c
Butterfly Valve
A 90-degree turn of valve stem change^
valve from completely closed 10 com-
pletely open
-------
10-17
Fioure 10-f
Check \il\t\ Us*d To Proenl Backflow
mf
Lift ChLxk \ jKc. Gl"l
rl
Lid Check VaKc. Angle
Tilunp-Disc Check Valve
_L
Swing Check Valve
-------
10-17
Fioure 10-f
Check N«l\r. Vscd To Present Backflow
. GI..K
Lift Check Vahc. Anplc
Chci-k Vahc
_L
Swing Check Valve
-------
10-1P
Ficure 1P-7
Cross-Section of Check Valves
SWING CHECK
fISTON CHECK
BALL CHECK
CLOSED PARTIAUY OPEN
SECTION A-A
-------
10-19
Fioure 1P-P
Types of Couplings
1. Ordinary Quick Dteconrwct
2. Quick Dtocormet Ptu* B*l V«tv«
3. Dry Di»eonn«ct
-------
10-PO
available types of couplings. ><. nrt. Jf the rnxinp of Incorpatible liquids
1t 1s Important t' Delect coupli -."* adapters that are corpatible with each
other.
TrM' f tr:' in the fill box rev be useful in soaHnc-up SFB!! spills.
These bears > "n c^sor. hydrocarbons and expanr1 rpny tires their size. The
owner/operator rust be aware that these beads do not absorb water, however,
anc4 should be evaluated for conpatibility with the spilled waste.
10.1.1.1.? Proper Operating Practices During Loading and Unloading
In addition to utilizing appropriate spill/overflow prevention control
devices, certain sound op?ratino practices should also be followed to prevent
spills/overfills durinp Ir ^'np and unloadinp. Pecornended practices that are
?r>^i ice1" V tr t^e s?fe transfer of any hazard. $ licind include t^p following:
(1^ The driver, operator or attendant any tank vehicle should
neith-:" retrain in the vehicle nor the vehicle unattended
durin the loading or unloading pr The delivery hose is
consic^'-ed to be part of the vehicle durinp the
unloandinp/loadinp process. The jerseeinp the process
should be aware of thi« and anv ^ problens associated;
with this. In additic *L ^onsi. arson rust be aware
of all other potential ~s &r * --ors (overfillinp,
leav-s, spills, vapor or , .TO expt *oi fire c*r. ) and
should rerein alert at all tires. Hi; t -* "fror
cause of transfer spill incidents, a ~^r sp H
could be avoided through proper persr din, and alert
observation of all operations. To r~ ., _. the potential for
hurren error sore corpanies prefer tc *^ave their OV.TI trained
personnel oversee the unloading operations.
(2) Loading and unloading of tank vehicle? should be done in
approved locations.
(?) In order to rrinirrize the possibility of f''»-e or explosion, when
transferring Class I or flamreble 11q '<,, irotors of tank
,-Mcles or mctors of auxiliary or por -> punps should be
'wjt down d----''' making or breaking he;, connections. In
- if -Dtor of the tank vehicle is not required for
^/i ding process the rotor should be kept off
e transfer of the liquid.
-------
<
(3) In order to minimize the possibility of fire or explosion, when
transferring Class I or flammable "Moulds, rotors of tank
vehicles or rotors of auxiliary or portable pumps should be
shut down during making or breaking hose connections. In
addition, if the rotor of the tank vehicle is not required for
the loading/unloading process the rotor should be kept off
throughout the transfer of the liouid.
(&} Care- tar^s containing volatile, flarn-pble or corbustible
liouid should not be fully loadec. Sufficient space or outage
rrust be provided to prevent leakage due to thermal expansion of
the liquid transferred. One percent is the rrininuir recommended
outage requirements.
(5) Delivery of Class I liquids to underground tanks of rore than
10,000 gal. (3800L) capacity mjst be' rade by means of tight
connections between the hose and fill pipe.
(f) No flamrable or corrbustible liouid shall be transferred to or
fror any tank vehicle unless the parking brake is set securely
and all other precautions have been taken to prevent motion of
the vehicle.
(7) Use of labels, markings or color codes on hoses and special
couplings that can be used only for transferring product can
prevent accidental mixing of inconpatible materials.
(8) Periodic inspection of hoses for leaks must be conducted.
Please refer to FFP£ 385 (Section f-? - Loading and Unloading of TanV
Vehicles) for rr>re inforrrBtion on loadino a^d unloading practices.
10.1.1.? ftTiforouncVIncrounc1 Tanks - Transfer Spills and Overfill
P«»evcn+>'fr $ V S t P PS f Or AS TV? C""0l!r !" ' l\ P CrOUT *
1 0. 1 . 1 . ?. 1 Pecopnended Prevention Systeps Flerents - Sutrrery
Transfer spills and overfills for aboveground/inground tanks can best be
prevented by using the equipment and practices outlined 1n this section. Much
of the recommended equipment and practices are also applicable to underground
tanks as cited in the underground tanks section. These elements Include:
1) Installing a complete overfill prevention system, Including:
o Level sensors and gauges to indicate the liquid level in the
-------
IP-??
o Hiph level alarirs;
o Automatic shutdown controls or automatic flow diversion
controls to prevent overfilling;
o Provisions for ererpency overflow to adjacent tanks to collect
overflowinp raterials;
o Paily monitorinp of the syster by a reliable individual
?) Hazardous wastes should be transferred at established stations
equipped with curbing, pavinp and catchrent facilities.
3} As with underground tank systerre, dry connect couplings should be
used on transfer pipes and hoses.
4) Redundant valves and instrumentation should be Installed.
See Figure 10-9 for an illustration of an overfill prevention systerr.
Level sensing devices that ray be used in aboveground/inground tanks
include:
fl ) float activated devices;
(?) displacer devices;
(?) hydrastic head devices;
(£) capacitance devices:
(f) ultrasonic devices; and
(7) optical devices.
Capacitance, therrel conductivity, ultrasonic and optical devices and their
applicability were discussed in detail 1n the underground tanks sections. As
certain float activated, displacer and hydrostatic (prerssure devices), are
prirarily applicable to aboveground and inpround tanks, these will be
discussed in depth below.
-------
10-73
Fioure 10-9
Eterrwnts of an Ov«rfl Pr»v«ntton Systwn
Hollof V«lv*
(Otcrtlll V«nt)
High
Tr«n»mitt«r
Ovarflow
to A«J«e«»t Tanks
n
L*v*l Controller
Motor Oporatod
Pump
-------
10-P4
Level -sensing devices may be top-mounted or side-mounted depending on the
type of device and the locatlnof the probe connection on the tank. The
material out of which the probe 1s constructed rust be carefully selectee1 so
as to ensure compatibility with the liquid In the tank.
See Table 10-' for a corpgrison of different level -detectinp devices
indicating the types of gauges, alarrrs and automatic controls with which they
can be interfaced.
Float Systerrs. As aforerrentioned, float activated devices are
characterized by a bouyant ranter that floats on the surface of the stored
hazardous liquid. Float devices are classified on the basis of the method
used to couple the float notion to the indicatinp irechanisir (gauge). Chain or
tape float gauges, lever and shaft float gauges and ragnetically coupled
Chain or tape float gauges - As indicated in Figure 10-10 these
devices consist of a float connected by a tape or a chain to a board
or indicator dial. Because of their low cost and reliability, these
gauges are comronly used in larpe atmospheric storage tanks.
Drawbacks to usinc these devices include: (1) potential for getting
out of alignment; (?} corrosion of the float material when
in'porperly selected; and (?) potential for jam'np and freezinp of
the HoM l
Lever I Shaft Float Gauges - These gauges are characterized by a
hollow metal sphere, sometimes filled with polyurethane foar and a
-------
10-?5
Table 10-4
Level Detection Devices for Overfill Protection Systems
for Aboveground Storage Tanks
Type of Device
Float Actuated Devices
Tape or Chain float gauges
Monitor
Liquid
Level
Yes
Lever and shaft rechanisrrs Yes
Magnetically-coupled Yes
Dlsplayer Devices
Flexure-tuKe disc^sce" Yes
Magnetically-coupled Yes
Displacers
Torgue tube displacers
Pressure Devices
Head system on pressurized
Bubble-tu'Ke systers
Pressure ga.pe - open vessel Yes
Capacitance Devices
Theriml Conductivity
Devices
Ultrasonic Devices
Optical Devices
Level
Indi-
cation Alerr and Shutoff Response
Gauge Interfaces with electronic or
pneuratic controls
Gauge Interfaces with electronic
pneuratic controls
Gauge Interfaces with electronic or
pneuretic controls
Paupe Interfaces with electronic or
r-.-iJ: cr--- ,
Gauge Mechanical
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Gauge
Paupe
Paupe
Paupe
Gauge
Gauge
Gauge
Gauge
Interfaces with electronic or
pneuretic controls
Interfaces with electronic or
pneuretic control?
Interfaces with electronic or
pneuretic controls
Audible alarrr and autoretic
shutoff; electronic controls
Audible alarir and autoratic
electronic controls
Audible alarir and autoretic
shutoff; electronic controls
Audible alartr and autoratic
crntro''s
-------
10-?6
Figure 10-10
Chain and Tapa Float Gaugas Uaad for Laval Control
_
Wires
FlOlt I
§»«r«
0*ug«
Indicator
Di*l(
-------
10-P7
lever attached to a rotary shaft that transmits the float notion to
the exterior of the vessel via a rotary seal. These float systems
are applicable to atmospheric as well as pressurized tanks. Again,
selection of an appropriate float imterial Is necessary to ensure
compatibility with the hazardous liouid. [See Figure 10-11.1
Macnatically Couplet* Floats - *s indicated In Figure 10-1?, these
deivces consist of a permanent magnet attached to a privoted mercury
switch. The float and guide tube that core 1n contact with the
measured liquid are available in a varitey of materials for
resistance to corrosion and chemical attack. These gauges ray be
used in conunction with pneumatic and electronic controls to operate
pumps, valves, alarms and other external systems.
i g^f r Systen?. The?p dev-ce? u?? the buoyant fo^ce of a partially
submerged displacer as a measure of liouic1 level. A:curate rreasurrent 'of
liguid level with displacement devices depends upon precise knowledge of
liquid and vapor densities. These systems can be used in cage mountings, or
side mountings in vented (atmospheric), pressurized, or evacuated (vacuum)
tanks. Flexure-tube, magnetically coupled and tongue-tube displacers, three
commonly used displacer systems will be briefly described below.
o Flexure -Tube Displacers as compared to other devices are realtively
s1' Tie, consistinp of an elliptical or cylindrical float rourter' on
a short arr connected to the free end of a flexible tube. The fixer
end of the same tube is attached to a mounting flange. [See Figure
10-13.] These devices are side-mounted and are most typically used
to directly activate either an electrical level switch or a
pneumatic pilot.
o Magnetically coupled displacers are displacer activated units
characterized by ragnetic coupling. These types of devices are most *
often mounted in external displacer cages and reouire two tank
-------
io-?e
Fioure 10-11
Lava! and Shan Float Qaugat Uaad for Laval Control
-------
10-?9
Floure 10-12
Magn«tfc*y Couptod Float* U»«d for L«v«l Control
Enclosing T«h«
Upp«r Magnet
twitch
Switch Arm
D*pr«*»*d
Low*r Magnet
Float
LOW LEVEL
HIGH LEVRL
-------
10-31
o connections, one above and ant* one below the liquid level.
Magnetically coupled displacers are compatible with both pneuratic
and electronic controls. f:See Flpure 10-14 for 11 lustration.!
t
o Tongue-tube displacers are a mono the frost widely used
level -measurinp devices. This device is suspended on a displacer
rod attached to a tonpue tube. [See Figure 10-15.1
Hydroastic Head or Pressure Devices. Js with displacer devices, an
accurate measurement of liquid level by hydrostatic head or pressure device
depends on a precise knowledge of liquid and vapor densities Inside the tank.
Host of these types of systems utilize standard pressure or differential
measuring devices and are conpatible with either pneumatic or electronic
controls. Pressure gauge systems on open vessels, bubble tube systems, and
heat4 systems on pressurized tanks are corron /recommended varieties of pressure
devices that will be briefly described belov.. '
o Pressure gauge systems In open vessels represent the sinplest
application of head level measurement, with the pressure ireasuring
element being located at or below the minimum operating level in the
tank. The owner or operator nust note that the pressure piping
between the open vessel the measuring element rust be sloped upward
toward the vessel in order to prevent errors due to entrapped air or
othpr gases. £ drain valve should be provided at the reasurinc
element to a T!CK sedirpnt to be flushed frorr the piping. This type
of level sensing device is conpatible with both pneumatic and
electronic controls although electro-pneuratic converters rmy be
required when electronic controls are used.
o Bubble tube systens are characterized by a tube Inserted 1n the tank
through which an air stream 1s ra1nta1ned. Pressure required to
keep the liquid out of the tube is proportional to the liquid level
in the tank. Bubble tube systems are particularly appropriate with
-------
10-3?
Fioure ID-IB
Torque Tube Dtoptocer UMd for Level Control
Fipure 10-16
Bubble Tube System Uted tor L«vel Control
CeMUnt now
-------
10-33
corrosive and viscous liquids, liquids containlnp entraned solids,
and liquids subject to freezing. These systems are rest commonly
used 1n conjunction with pneumatic controls but 1n irost cases my
also be used with electronic controls if electro-pneumatic
converters are provided. Bubble tube systers are 1n most instances
more expensive than float or displacer type system as they reouire
a constant supply of lean and dry instrument air. [See Figure 10-16
for an illustration of a buble tube systerr. 1
o With head systere on pressurized tanks the measurement of liquid
level differs fror that in open vessels 1n that a differential
pressure measurement is taken. When utilizing this syterr any of the
conventional differential pressure measuring devices maybe used.
ccTpcfior- rf t^e arrTrri3te hydrrstatic/rressure is very irportant. Several
factors impact on the accuracy of this type of level measuring system As
aforementioned, the density and vapor pressure of the hazardous liquid nust be
known. Hydrostatic heads that a^e not used for level measurement must be
eliminated or compensated for. The level above the lower tank connection
(i.e. the discharge connection in the case of an aboveground tank and the fill
connection in the case of an underground tank) is measured by the differential
pressure across the measuring element. This particular measurement is only
accurate if the following conditions are met: (1) compensation is made for
any deviation of the density of the liouid: (?) the connection of the low
pressure side of the measuring elf rent contains no liauid that has accunulatec'
because of overflow or condensation; (3) the density of the air-vapor mixture
above the liquid is either negligible or compensated for; and M) the
measuring element is located at the same elevation as the irininum level to be
measured, or suitable compensation 1s imde. Finally, as mentioned, either
pneumatic or electronic controls ray be used with these devices.
-------
10-?*
10.1.1.?.!.!.? High Level Alarrrs
A high level alarir systeir 1s essential to perforrance of an overfill
prevention systeir. Fither audible and/or Indicator light devices are
acceptable. When ronitoring several tanks at one tire it 1s reconranded that
both audible and visual alarrc be used. In this case one indicator light per
tank is usually necessary to alert the operator as to which tank is
overfilling. In any event an indicator light should be placed where it can be
readily seen by the individual responsible for control of the filling
operation.
10.1.1.2.1.1.3 Automatic Shutdown or Flow Diversion
Another iroortant element in the overfill prevention systerr is the
automatic shutdown or control device. In the case of an inpending overfill
these devices automatically shut down to stop flow or divert flow altogether.
THS device ?rt? ir> c^iunct-'on ^"'^ ^p level-sensinr device to Derforr one
or rore of the following functions:
Prevent tank overfilling by shutting off the tank loading puro.
Prevent damage to the tank unloading pump by shutting it off at a
low level.
Operate various flow control valves and pumps to divert flow to
^e*- stfoo? tank if an overfill situation occurs.
Control devices can be provided for loading a predeteririned Quantity of
liquids as well. For exarple, a loading area at a tank truck loading station
could be equipped with a level-sensing device and autormtic control system
which shuts off the flow of liquid when a predeterirtned level Is reached 1n
the tank truck. As rentioned in the underground tanks section, automatic
control devices can be electrical, pneuretlc or nechanlcal 1n nature.
Electrical and pneuratic controls tend to be more widely used as they have
fewer roving parts and are rore adaptable to rerrote operation. (See Figure
10-17 for an illustration of a loading area equipped with an autoimtic shutoff
-------
10-35
Floure 10-17
Loadino firir Fquippec4
With Autoratic Shutoff
automatic
shutoff valve
level sensing
device
ng circur mdcpcide"; of product flo* file,
prfsvurt or temperature
Cm be operated electrically or prxumaticj">
Source Emco Wheaton Inc . Fluid Handling Systems Catalog
Emco Wheaton. Inc . Chamberlain BKd . Conneaut, OH
44030. Revised Apnl 1977
-------
10-?6
10. 1.1.?. 1.1. 4 Frergency Overflow to Adjacent Tanks
An emergency overflow system 1s another Iwportant element 1n a coirplete
overfill prevention systerr. This type of systerr can be activated by the
autoratic control In the event that tank overfill ing cannot be avoided through
other means (i.e. pump shutdown). Such a systerr can also be manually operated
in the event that the autormtic control system malfunctions. In addition,
provisions must be made for a final overflow to the external environrent in
case the entire syster, tank and emergency overflow tank ere filled to
capacity. It is advised that this particular overflow point be rede visible.
10. 1.1.?. 1.1.5. Monitoring Systeirs
System failure can be minimized if the system is monitored on a daily
basis for such things as expired batteries, low electrical connections
unplugged inlet cords etc ---- Sorretimes the most minor details can seriously
with syster
In addition to installing a complete overfill prevention system with the
appropriate equipment other operating practices should be followed.
10. 1.1. ?. 1.1. f Dry Disconnect Couplings
£s addressed in the underground tank section, dry disconnect couplings
should be used on transfer pipes and hoses in place of ouick disconnect
couplings or other less reliable means of pipe and hose connections.
10. 1.1. ?. 1. 1. 7 PedunVant Valvino and Instrumentation
Because valving instruments can malfunction and lead to disastrous
conditions use of redundant valving and Instrumentation is recommended.
Redundant valves and instrumentation are an Inexpensive way to avoid spills.
The prlirary valve controls should be visible to the overseer. Communication
should be mlntained with the remote secondary valve control operator during
waste loading/unloading.
-------
k. ~-
10-37
10.1.1.7.1.1.8 Use of Fstablished Stations
Transfer operations should only be conducted 1n specifically designated
transfer areas eouipped with Inpervlous surfaces, curbing and spill catchment
facilities, should any spills occur.
IP.1.1. 7.1.1.9 Proper Transfer Practices
Refer to discussions in underpround tanks section 10.1.1.1.? for
inforration on liquid transfer practices. The sane transfer practices are
applicable to both underpround and aboveground/inground tanks. [/Hso refer to
NFPA 385 for further inforration on loading and unloading practices.1
10.1.1.7.1.1.10 Inspection and Maintenance
All of the eleirents of a tranfer spill prevention system should be
inspected on a regular basis and repaired or replaced pronptly when darape is
^tectec1. Pecjlar insrect1-rn anr1 maintenance are critical tc er efficient
transfer spill prevention system. Elements that should be inspected include:
Hoses, piping, fitting, etc.,
Couplings,
Curbs, containment surfaces and catchbasins,
Loading area assemblies,
Purrps and valves,
All control instrumentation,
A'll tank? enc< tanV vehicles.
10.1.1.3 Uncovered Tanks - Freeboard
As 264.194 (b) (3) stipulates owners and operators of uncovered hazardous
waste tanks rust allow for utlntalnance of sufficient freeboard to prevent
overlapping by wave or wind action or by precipitation. In a tank of less
than 100 neters 1n diameter the iraxlrnjir height of a wind-induced wave 1s 4 to
5 Inches. Allowing for another four to five inches for splashing on the sides
and up to six inches for any precipitation, 14 to 16 inches of freeboard is
considered adequate for rost tanks and 18 inches is considered to provide rare
rr a safetv fc:tr<-.
-------
10-3B
ID.? Major Issue Points
This subsection, a summry of the Inforration covered 1n this section,
ray be used in assuring the conpleteness of a Part B subrittal. It can be
helpful in planning, preparing and verifying the adeouacy of a spin/overfill
prevention system.
It is recorranded that a spill/overfill prevention systerr include the
following:
Underground Tanks
J) Flerrents of an Overfill Prevention Systerr.
1) Sensors for detecting the level of liquid in the tank
*a ) Float activated devices
*c ) Therral conductivity sensors
*d) Ultrasonic sensors
*e) Optical sensors
f) Displayer devices
g) Hydrostatic head sensors
2) High level alarrs which are activated when a tank overfill is
i mm'nent
3) Autoratic shut-off devices which prevent overfill inq fror
occurring
&} Tieinp -in the unloadinc process with t^e overfill prevention
syster to prevent any unloading1 vtien the overfill prevention
systerr is non-operative
5) A bypass prevention systerr ensures that the overfill prevention
systeir cannot be overridden by the operator.
B) Elerents of a Transfer Spin Prevention Systeir
1) Couplings equipped with spring loaded values which
automatically block flow when hoses are disconnected
Ouick disconnect couplings
Dry disconnect couplings
£],, Erreraency shut-off valves
. Mlow appropriate transfer practices.
applicable to Underoround Tanks
-------
10-39
Aboveground/Inground Tanks
J) Flerents of an Overfill Prevention System:
1) Level sensors and oaupes to indicate the liquid level 1n the
tank
**a) Float activated devices
**tO Displacer devices
**c) Hydrostatic heac1 devices
d) Capacitance devices
e) Therral conductivity devices
f) Ultrasonic devices
o) Optical devices
2) Hiph level alarirs;
?) AutoTOtic shutdown controls or autoratlc flow diversion
controls to prevent overfilling;
&} Provisions for eneroency overflow to adjacent tanks to collect
overflowinp
?) Daily ronitorino of t">e syster by a reliable individual.
B) Flements of a Transfer Spill Prevention System:
1) Hazardous wastes should be transferred at established stations
equipped with curbinp, pavinp and catchment facilities;
2) As with underprounc1 s,ysters, dry disconnect couplinps should be
used on transfer pipes and hoses
?) Redundant valves and instrumentation.
n Jpprop'-istf transfer practices should he follow?^.
4
** f-1ost applicable in Aboveground/Inpround Tanks
-------
11-1
11.0 INSPECTIONS
Tank systems must be properly inspected on a routine basis to minimize
the probability of accidental releases of hazardous materials to the
environment. Inspections also aid in reducing the risks of fire and exposure
resultino fro"-, haza^dcj? releases and to maintain safe working conditions in
and around the storaae area. Regular inspections using appropriate and
effective procedures are the most reliable mechanisms available for
forecasting the potential for tank system failure. Most effective inspection
programs will identify excessive corrosion or erosion, deterioration of
non-metallic liners and appurtenances, cracking of welds and joints,
structural fatigue evidenced by cracking of metals, and leakage from pumps,
valves or pipina. Particular attention should be given to bottom-to-shell
connections; flanges; rivet holes; welded seams; valves, nozzles and welded
The freauency of inspections should depend on the severity of the threat
to human health and the environment presented by a detected or possible leak
at the1 storage facility. An inspection program should at the very least
consist of visual inspections at regular intervals. Visual inspections are
the simplest method for detecting corroded or leaking facilities. Corrosion
most often results in eventual leakaae and rupture of tank systems. Ea^ly
detection and replacement of facility eguipment can prevent catastrophic
leakaao. Tank svste^ should be inspected externally and intemallv, hut,
since the tank systems 3"e usually in continuous service, external inspections
can be carried out more readily and freguently.
11 .1 Regulatory Citations General
Information on inspection schedules must be included in Part B of the
permit application as specified in :
-------
11-2
"270.14(b)(5) A copy of the general inspection schedule reauired by
264.15(b); included where applicable as part of the inspection schedule,
specific requirements in 264.195 for tanks."
Fo" ou*1 purposes herp we will only address specific inspection
requ^re^e-its for hazardous w?ste tanks. See Permit Aoplicant's Guidance
Manual for the General Facility Standards of 40 CFR 264 Section 5.5 for
information on general inspection requirements. Early detection and
replacement of faulty equipment is therefore critical to spill/leak
prevention. Tank and ancillary equipment should be inspected externally and
internally, but, since the tank systems are usually in continuous service,
external inspections can be carried out more readily and frequently.
The following subsections adcress the inspection requirements of the
rec i^eti crs anr1 en :<= Jete"ls on the methods and frequency of equipment
inspections. In cetera"!, most of this chapter addresses metal tan»,
conditions. Fiberglass-reinforced plastic tanks are a bit different in that
they often fail by different mechanisms of deterioration than metal tanks.
Sub-section 11.1.5.1.11 includes specific FRP tank inspection information.
Any hazardous facility that uses tanks to treat or store hazardous waste
must, in addition to the general inspection requirements of 264.15, comply
with the specific inspection reou irements of 26^.195 for tanks (see Table
11-1). These inspection requirements will be discussed individually in the
ov.'ing sub-sections.
11.1.1 Regulatory Citations - Schedule R Procedures for Overfill Control
System Inspections
Part B of the permit application must include a schedule and procedure
for inspecting overfill control systems and monitoring equipment in all
tanks:
-------
n-3
Table 11-1
Inspection Reauirements
Sg:f r
Inspection
264.195(a)
264.195(b)(l)(2)
Ove^f il 1 Controls
Visual Inspection of Aboveground
Portions of the Tank
- corrosion or leakina from fix-
tures, joints and seams
- monitoring and leak detection
eauipment (pressure or temper-
ature qauaes, monitorina wells
and leak detection devices)
Externally accessible portion of
the tank
- construction materials
- secondary containment system
to detect erosion or signs of
leakage (e.a. wet spots, dead
veoetation)
Develop Schedule
Daily
Ueekly
Impressed Current Systems
anode deterioration
- rectifier malfunction
power interruption
- rectifier output
Anode Output of the Sacrificial
Anode or Galvanic Cathodic
Protection System
Tank System-to-Soil Potential
Measurement
Monthly
Semiannual 1y
Annually
Overall Assessment of Tank Condition
Develop a Schedule
-------
n-4
"?6d.l95(a) The owner or operator of a tank system must develop
a schedule and procedure for inspecting overfill controls, where
present (e.Q- level -sens ing devices, high level alarms, waste feed
cutoff and bvpass systems)."
11 .1 .1 .1 Guidance
Important overfill controls and instruments include:
o Flow rate controls
o Level controls
o Te"iperature qauqes
o Pressure gauaes
c ^tT1 valves
*
o A"!ar~i ar'i e^e-ce^cv s^t-o** devices
o Analyzers
A brief checklist of what should be inspected in regard to these
instruments, control eauipment and electrical systems includes the follow in a:
Transmission systems
Powe1* SUDD! ies
Sea^s
Panels and enclosures
Electrical equipment
Insulation
Enclosures
Operating Mechanisms
Insulating and lubricating oils
Protective overlays
-------
11-5
Bearinqs
Batteries
Rectifiers
In rv>st cases, instruments and controls are visually i^isDected dai^y by
the oDer?tor" since thev a"e an intearal part of the daily c;p-eration of the
facility. Any unexpected discontinuities or abnormal peak*, in data charts or
data logs may indicate that there is some cause for concern. All
instrumentation and control eauipment should be thoroughly inspected and
calculated accordinc to the manufacturers' recommended freauency and
methodology.
Environmental conditions such as heat, moisture, chemital attack and dirt
a-e responsible for deterioration of electrical systems. Tte -visua1 inspector
(jHnj'ir1 c no f* f i rs : 1 y " r>v. ^^r ^KocP d° tOT" i Or gt i n Q ?ffeCtS.
*
11.1.2 Regulatory Citation Daily Inspections of Ahoveoroimtl Portions of
Tank Systems and Monitorinq and Leak Detection Data
"264.1Q5(b) the owner or operator must inspect at least once each
operating day: (1) the abovearound portions of the tank system, if any, tc
detect corrosion or leaking of waste from fixtures, joints a'nd sea^s; anj (2^
data Gathered f<-cr continuous monitorina and leak detection eauipment, if any
(e.a. pressure 0" te~oerature aauaes, monitorina wells, leak-detectic^
devices) to ersu"-e t^at the tank system is beina operated accordinc to its
design."
11.1.2.1 Guidance
Daily inspection of the aboveground portions of the tank for corrosion or
leaks from tank fixtures, joints and seams and careful inspection of data from
leak detection systems, should be standard operating procedure for tank owners
-------
11-6
Gross leakage or corrosion from fixtures and seams will be readily
evident. This is the primary purpose of a daily visual inspection. Careful
visual inspection is required to detect deteriorating areas before they
develop into serious problems. This is the purpose of the more thorough
weekly exte^ns1 inspection of the tank and overall assessment of tani
condition whic^ is discusser! in 'jubseauent subsections. Stres? co^rosio"
around weld seams, joints and fixtures may occur on the surface of the tank.
Careful daily inspection of aboveground portions for corrosion will usually
suffice in detecting potential defects which then reauire further detailed
examination. Visual inspections are usually sufficient to locate major
corroded areas on abovearound portions of the tank.
In addition to daily inspection for corrosion, the aboveground portions
of the tank shell should be inspected for leaks, cracks, buckles and bulges.
ni^c1"^ i?"** "> "^ c* o^i1"!* in th° 3»-p? hoi Q,.,I the leak is nften an indication n-f
. . - -
1 eak aae .
Cracks can be found at nozzle connections, in welded seams, and
underneath rivets. Cracks, buckles and bulges can initially be spotted by
visual inspection, and their extent can be more thoroughly determined by
technioues such as the tnaon»tic-particle, penetrant-dye or vacuu^ box methods
(see Section 11.1.5.1.8 for further detail on inspection devices).
All valve^ 01 the tank should he visually inspected to ensure that the
seating surfaces are in aood condition.
Concerning daily inspection of data from leak detection eauipment such as
pressure or temperature gauges and monitoring wells,, persons charged with
recording the data, should be adequately trained as to acceptable values and
must notify the responsible supervisor when such values have been exceded.
-------
n-7
11.1.3 Regulatory Citation - Weekly Inspection of Construction Materials,
Tocal Areas and Secondary-Containment System for Erosion or Leakage
"264.195(c). The owner or operator must inspect on at least a weekly
basis the construction materials of, and the area immediately surrounding the
externally accessible portion of the tank system and the secondary-containment
system, to detect erosion or signs of leakage (e.g. wet spots, deac
vegetation)."
11.1.3.1 Guidance
264.195(c) requires weekly inspection of the construction materials and
the area immediately surrounding the external portion of the tank system and
the secondary containment systems for signs of erosion or leakage. This
wee!,iy ins:>?: "."' o-"* is no* to bc confused with the detailed assessment of the
condition o* the tan* WHIG-; wiTi be discussed 'ater in this secno'. Tn^s
weekly inspection is primarily intended to detect leaks or the potential for
imminent leaks (much like the daily inspections except this is a bit more
thorough). Items that should be assessed during these weekly inspections
include:
o Leakage or corrosion around nozzles and piping of the tank
syste^;
0 Si o- s of Corrosion of tank tops or roofs;
o Vai functi on inc of roof seals and/or drains if included in the
system;
o Corrosion or leaks, cracks, buckles on seams and plates of the
tank wall and tank bottom;
o Possible erosion around foundation and pads and secondary
containment, if any;
o Deterioration of protective coatings indicated by corrosion,
blisters, discoloration or other film lifting.
-------
11-8
Visual inspection, picking, scraping and hammering are efficient
procedures for loeatino major corroded areas on ahoveoround portions of the
tank.
Leak testina devices such as ultrasonic or vacuum devices are efficient
leak testina mechanises . F See Section 11.1.5.1.B of this text for details of
these inspection devices1.
In addition, careful inspection of insulation surroundinq the external
portion of the tank for leaks is recommended if insulation is present. As
mentioned, this inspection is meant to be strictly visual. More sophisticated
inspection methods should be employed upon discovery of a defect.
11.1.4 Regulatory Citation Inspection of Cathodic-Protection Systems
"264.19: vc ,. The Owner or operator r.uil inspect, catnoc! :c -prote:i?c<
systems, if present, according to, at a minimum, the following schedule to
ensure that they are proper1y functioning:
(1) the operation and components of impressed current systems must
he inspected at least monthly fo<- such items as: anode
deterioration, rectifier malfunction, powe^ interruption, and
rectifier output ;
(2) the anode output of a sacrificial anode system must be
ected at least semiannual lv; and
(3) the tank syste~-to-soil potential measurement must be conducted
at least annually to ensure a minimum level of -0.85 volts."
11.1.4.1 Guidance
Storage systems equipped with cathodic or anodic corrosion controls
require periodic inspection of those controls if they are to provide long-term
protection. Conditions that affect protection are subject to change with
time. Corresponding changes may be required in the cathodic protection system
-------
11-9
to maintain protection. Conditions may exist where operatina experience
indicates that testing and inspections should be conducted more frequently
than required herein.
o _?fifl.195fdUl ) reauires, at minimum, a monthly inspection of the
operation and components of impressed current system such as anod'2
deterioration, rectifier malfunctions, rectifier output and powe>-
interruption.
As a particular type of cathodic protection system, impressed current
anodes are usually composed of materials such as graphite, high silicon cast
iron, platinun, magnetite or steel. These anodes are installed either bare or
in special backfill material. They are connected by an insulated conductor,
either singly Or in aroups, to the positive terminal of a direct current
source. Thov a--c dynamic svste^s rpQuirina close supervision and maintenance
oversight. *
Impressed current electrode systems require inspection to detect
potential malfunction due to power interruption, imprope" operation of
rectifiers, deterioration of anodes, bonding discontinuity, or broken wires.
Rectifier outpjt should be monitored monthly with a voltage or a^peraoe
indicator, and adjusted as needed. Internal connections should be checked for
mechanical security. Tank-to-soil potential measurements should be made
'monthly to determine if rectifier adjustments are needed to maintain adequate
corrosion protection.
Impressed current anodes should be inspected for defects, conformance to
specified anode material, size and length of lead wires, and to ensure that
the cap, if used, is secured.
In addition, the lead wire should be carefully inspected for defects in
insulation. Care must be taken to avoid damage to insulation or wire. If
defects are found in the lead wire, that wire must be replaced or the anode
must be rejected.
-------
11-10
According to NACE Standards "Control of External Corrosion on Metallic
Buried, Partially Buried or Submerged Liquid Storage Systems,"* all sources of
impressed current systems should be inspected for malfunction. NACE
stipulates that proper function ina may he indicated by current output, a
signal indicatina normal operating, satisfactory electrical state of the
protected structure or normal power consumption.
NACE recommends the inspection of protective facilities; check ina for
electrical shorts, around connection, circuit resistence, and meter accuracy
and efficiency. Isolating devices, continuity bonds and insulators should
also be evaluated by on-site inspection or by evaluating corrosion test data.
Other NACE recommndations include:
When the structure being Detected is not covered, it should be
examinee1 for corrosion, and, if coated, condition of the
C > 3 * * - r e li n ^ ^ ^ e s
The condition of test equipment for obtainina electrical values
should be maintained and checked annually for accuracy.
For further in'or-nati on on renedial action procedures when test and
inspection criteria indicate that protection is no longer adequate see NACE
standards "Control o* External Corrosion of Metallic Buried, Partially Buried,
or Submerged Liouid Stcraoe Systems."*
o P^.1 95- c1 } ' ?} recuires the anode output of a sacri-Mcie"! ar ode
system to he inspected at least semiannual lv. Sacrificial abodes 0" aalva^ic
anodes are composed of a metal that, because of its relative positio" in t'^e
galvanic series, provides sacrificial protection to metal or metals that are
more noble in these series when coupled in an electrolyte. These anodes are
the current source in this type of cathodic protection.
*Source: NACE Standards," Control of External Corrosion of Metallic, Buried,
Partially Buried or Submerged Liquid Storage Systems," March ?Q,
1985 Section 10.
-------
11-11
As mentioned with impressed current systems, storage systems eain'poed
with cathodic or anodic corrosion controls reouire periodic inspection of
those controls if they are to provide long-term protection. For these
galvanic anode systems the regulations reauire at least semiannual
measurements of tank-to-soil potential and anode output. Galvanic systems
should be checked for broken w^res, broker or shorted insulators, or loss of
coatings.
o 26&.195(d)(3) reauires that the tank system-to-soil potential
measurements be conducted at least annually to ensure a minimum level of -0.85
volts. Tank system-to-soil potential measurements are usually performed by
measuring the voltage between the tank or piping surface and a saturated
copper/copper sulfate reference electrode located on the electrolytic surface
(soil) as close as possble to the storaae system.
n zinc re'e^e ce elect-'oae, r,r a tes: station, S^OU'G be mils'n e; tc'e
depth halfway between the top and bottom of the tank, and midway between
tanks, if in a multiple tank field. This installation provides convenient
test positions to measure tank-to-soil potentials.
11 .1 .5 PEGL'LfT'-Y CITATIONS Schedule and Procedjre for Assessing Overall
Conc:' tiO1"1 of the Tank Syste""
"26-.19? ?) A schedule and procedure must be developed for assessing the
overall cone-for of the tank syste^. The schedule and proceaurp rjst be
adeauate to detect obvious cracks, leaks, and corrosion or erosion that may
lead to Cracks or leaks. The freauency of these assessments must be based on
the material of construction of the tank and its ancillary equipment, the age
of the system, the type of corrosion- or erosion-protection used, the rate of
corrosion or erosion observed during the previous inspection, and the
characteristics of the waste beinq stored or treated."
-------
11-12
11.1.5.1 GUIDANCE
The permit writer is responsible for specifying the frequency of
inspections required. The permit applicant is required to develop an
inspection procedure to assess the condition of its tank systems. The permit
writer should be concerned that the procedure proposed by the applicant wil1
detect any defect in the tank. A detailed assessment of tank condition
encompasses two phases, an external inspection phase and an interne1
inspection phase. [The API Publication, Guide for Inspection of Refine-y
Equipment, Chapter XIII, "Atmospheric and Low-Pressure Storage Tanks," 1931,
may be used as a guideline for assessing the overall condition of the tank
syster".l
11.1.5.1.1 Exte^na"1 Inspection
pa>"ts of an external tan-, 'inspection can be performed wvile tne tank
is in service, however-, some external procedures are best left to be performed
when the tank has been shut down and emptied. External inspections should
take into consideration the following aspects of the tank system: ladders,
stairways, platforms, walkways, pi:>e connections, anchor bolts, foundations,
protective coatings, insulation, tank walls, tank roofs and valves. rSee
checklist on Table 11-2. ^
Ladders, Stairways, Platforms and Walkways - Malfunction ing of this
eauipment wou'd not necessarily cause tank lea'-aae but can pose significant
safety hazards and are indicative of the condition of the tank in genera"1.
Check these appurtenances for structural stability and for missing treads,
rungs and handrails. Cracked and spalled concrete pedestals may lead to
stairway or walkway failure. Bolts should be checked for corrosion at the
contact points. Indication of rust stains through paint may indicate
corrosion and should be checked further. All suspected defects should be
recorded, marked with paint and repaired as soon as possible.
-------
11-13
Table 11-2
External Inspection Tank in Service
External Inspection
1. Ladders, St3irways, Dlatforrrs aid Walkways
missing treads, rungs and handrails
cracked or soalled concrete pedestals
low spots where water can collect
2. Foundations
erosion
uneven settlement
cracks and spall inq in concrete pads, base rinqs and piers
deterioration of water seal between tank bottom and the
f oundati on
distortion of ancho1" bo1 ts
buck lino of colu^s
V
3. Pine Connections
external corrosion
cracks and distortion
4". Protective Coatings
rust SDots, blisters and film liftina
5. T2n'. Walls
cohesion on the underside of
discoloration of Paint su-face
cracks at nozzle connections, T> weeded sea^s anc
lioaments between rivets
cracks, buckles and bulges
6. Tank Roofs
general corrosion signs
malfunctioning of seal
blockage of water drains on roofs
-------
n-i4
Foundations - Concrete curbing around the base of the foundation and
foundation ringwalls should be inspected for signs of deterioration. Cracks
or decay should be promptly repaired for structural integrity purposes and to
prevent liquids from collecting under the tank. A surveyor's level should be
used for checking evenness of foundation settlement. Concrete Pads, base
rings, pier; column leas and stands and any other general support structures
should be visually examined for cracks and spelling. Such deterioration can
also be uncovered by scraping the suspected areas. The joint between the tank
bottom and the concrete pad or base ring may have a seal for stoppina water
seepage. If so, this should also be inspected for corrosion. Wooden supports
for tanks should be checked for rotting by hammering. Anchor bolts can also
be checked for structural integrity and tightness by hammering. Excessive
foundation settlement is typically indicated by distortion of anchor bolts,
buckling of columns and excessive concrete crackinq. Welds along the angle
iron sf t^e ir*a"?ectior of the shell and tank bottom should be inspected for
de ten or ati OK =; well. (See noire 11-1.}
When abovegr'ound tanks are resting on a soil foundation, visual
inspection to detect leaks on the bottom plate of the tank is usually
impossible. TV,: methods are recommended in this case. The first method is
by soaping the seams or suspicious areas of the tank bottom and then applyinc
a gasketed vacjurr box. As a vacuum is drawn within, the box leaks will be
indicated by the anoearance of air bubbles. The vacuum box technioue can be
applied to a^'. surface. The vacuum box is not for use below the liauid line.
Exterior aroy: water leaks in. The second rethod is performed by p'acinq a
temporary clay dam or seal around the base of the tank and injecting air
underneath the tank. The pressure of the injected air should be equal to or
no more than three inches of water. Leaks will again evidence themselves as
air bubbles when a soap solution is applied to the interior tank bottom.
Pipe Connections - Pipe connections in tank systems nust be inspected
for external corrosion by visual examination, scraping and pickina. Piping
should be sc"apec! and cleaned durinq visual inspection. If severe soil
-------
11-15
Figure 11-1
(*< CtMct ';."'
. ." ..'
'c; c .''
SOURCE
in«lronm»nt. inc.. 1M3
AREAS OF CONCERN IN A TYPICAL TANK FOUNDATION
-------
11-16
corrosion is suspected, underground piping should be checked. When the tank
has shown evidence of excessive settling, pipino connections that may have
been loosened should be carefully checked.
Protective Coatings - Rust spots, blisters and film liftina of the
tan1- 's protective coatina a*-e best detected by visual inspection or by
scraping the film in suspected areas. Special attention should be paid to
paint blisters which are usually prevalent on the roof and sunny side of the
tank. Film lifting is prevalent below seam leaks.
Tank Halls - As mentioned under section 11.1.3 weekly inspection
requirements, inspection of tank walls for corrosion and leakage, are
extremely critical in the overall assessment of tank condition.
Tank Roofs - Corrosion in tank >-oof? can be detected by hammering.
»
Corrosion in tank roofs is due to weathering, paint wearing, foot traffic,
interior pitting with volatile vapors. Hammering is necessary as corrosion is
not always so obvious. Safety precautions however, such as wearing safety
belts, should be taken durinq these inspections. Gas tests as well as tests
for structural stability should be conducted prior to inspections to ensure
inspector safety as well. Use extended harrmer on exposure weakened section if
any. Water d"a ins on roofs should be inspected periodically for blockage.
11.1.5.1.? T9ri Cleaning
Prior to an internal inspection, tanks must be emptied and cleaned. A
* /
general overview of proper tank cleaning procedures is presented here.
[For more detailed procedural information see API Publication 2015, "Cleaning
I/ Source: Information referenced from Section 5 of "Toxic Substances,
Storage Tank, Containment Assurance and Safety, Program;;, Guide and Procedures
Manual," Maryland Department of Health I Mental Hygiene, 1983. M
-------
11-17
Petroleum Storage Tanks," September 1985, API 2015A, "A Guide for Control! ina
the Lead Hazard Associated with Tank Entry and Cleaninq," 1982, API 2015B,"
Cleaning Open-Top and Covered Floating-Roof Tanks," 1981, NIOSH, No. 80-106,
"Working In Confined Spaces," December 1979, and NFPA Standard 327 "Cleanina
and Safeauardino Small Tanks and Containers."1
Tank cleanina car, be an extremely dangerous task if not performed
carefully and correctly. Fire, explosion, oxygen deficiency and worker
posisoning may result from improper removal of even very small Quantities of
solid, liquid or gaseous remnants of haiardous constituents from tanks.
Therefore, particular attention should be aiven to ventilation and sludge
removal in the tank cleanina process.
The first major task in the tank cleaninc process involves externa1
jncno;*. -" po n* tho tan- 3nd pr e1 i ^ in a" v inspection of tank cleaninq eauipment.
Next tne ai
-------
11-18
water hose pointing inward from the tank shell may be used to loosen excess
sludge and float it to a water pump connection. All nozzles should he
electrically bonded to tank shells during use. All lighting and electrical
equipment used inside or near the tanks should be intrinsically safe or
grounded to c- eve-it so^k?. Vain ten an ce of adeauate ventilation at she"1''
manways durinc this process is essential. Vapor concentration should not r-Ke
above 50* of the lower flarrrnable limit. If the level gets above 50*, washino
should be stopped until a safe level of concentration is re-established.
Pumping equipment used for the removal of sludge and excess water from
tanks should be carefully selected. Equipment driven by air, steam, or an
approved electrical drive is preferred. [When it is necessary to resort to
open type, electric power o>- qaso1 ine driven pumping equipment see API 2015
"Cleaning Petroleum Sto^aae Tanks," for specifics.!
Steam t^eatme^t is the most convenient method for cleaning without
entry. After 10 minutes of steaming, the tank should be washed with hot water
and overflowed, if necessary, to remove solid debris.
ica1 cleaninc may be an alternative should steamina prove
inadeauate. W-en usinc hot chemical cleaning solutions temperatures of 170cr
to 190°F sho^'d be maintained. Cold chemical solutions should only be used
after de tern'- *na their compatibility with tank material.
Tan'.. Clewing V.~ tn Ent^y. A safe atmosphere must exist in the tank for
cleaning with entry. Prior to work, the interior of the tank should be
inspected for physical hazards that might fall such as loose rafters, angle
irons or columns. Oxygen and combustible gas readings should be taken at
freauent intervals while work is being performed in the tank.
Appropriate respiratory protection should be provided if the atmosphere
in the tank is unsafe. Also, positive air pressure full-face respiratory
equipment as well as protective clothing should be used.
-------
11-19
*/
A tank should never be entered if the following conditions exist:-
1. Oxygen percentage in the tank is less than 16%.
2. Flammable vapors are greater than 20* of the lower explosive limit
(LEO.
3. Mvijrooe0 sulfid<= concentrations are less than 100 parts per million.
&. Airborne concentrations of toxic vapors are above acceptable levels
set by the individual employer.
11. 1.5. 1.3 In tern a1 Inspection - Tanks Out of Service
The internal inspection involves two major phases, emptying the tank and
performing the actual inspections. Safety of personnel, and avoidance of
spills and other hazardous conditions should be of concern to the permit
applicant as well as the permit writer. Internal preliminary visual
bottom should all he an integral part of a complete internal inspection
program. See Table 11-3 for tank features that should be focused upon in an
internal inspection. Table 11-3 also notes advanced inspection techriques
that may be used.
Stress corrosion around weld seams, corrosion at the 1 iauid-vapor
interface, oxidative corrosion due to the presence of oxygen (from the air) in
'the vapor sn=ce of vented atmospheric tanks, caustic e^br ittle-nent , and
hycrogen b'iste-ina a-e all types of corrosion that may occu" in a rcr'-ur- forrr
way on the surface of the tank metal. Careful visual inspection, however, for
these types of corrosion will usually be adeauate to detect the possibility of
defects that require more detailed examination. In contrast, pitting is
another form of corrosion that in some cases may not readily be detected
through visual inspection. Thus, a visual inspection must often be
supplemented by special inspection equipment to assess a tank's condition
fully.
l7Source: nTT2015, "Cleaning Petroleum Storage Tanks," Septe^p>- 19??,
p. 13.
-------
n-?o
Table 11-3
list for Tank Internal Inspection
(Tank out of Service)
Solid Steel
(1 ) Roof and Structural Supports (visual first for safety)
no hazards of falling objects
(2) Roof and Structural Supports (more rigorous)
loss of metal thickness
cracks, leaks at welds
cracks at nozzle connections
malfunctioning of floating roof seals
water drain system deterioration
harmer testina, if necessary
(3) Tank Shell
cracking of plate joints
cracking of nozzle connection joints
loss of metal thickness
(4) Tank Bottom
corrosion pits
sp"uro of cracked seams
rivets for tightness and corrosion
depressions in bottom areas around or under rocf and pipe supports
botto^ thickness
uneveness of bottom
harrer testing and bottom sampling, if necessary
a?"?"?"1 conditio^ of liner (holes, creeks, gaps, corrosion, erosion.
sv-.V'ing hardness, loss of thickness)
proper positioning of liner
bulges, blisterina, or spall ing
spark testing with rubber, glass, and organic type coatings
ultrasonic examination o
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11-21
Table 11-3 (Continued)
Fiberglass-Reinforced Plastic Tanks
softenina, identations, cracks, exposed fibers, crazina, checHna,
lac* of su"face resin, and dela^inatioi
sufficiently translucent, discolored, porous, air or other bubbles
visible, other inclusions, and thin areas
hardness testinc of specimens exposed to liquid contents
ultrasonic examination of laminate thickness, if possible, if any
deterioration is suspected in the polyester matrix.
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n-22
Safety Precautions--As stressed in the preceeding section on tank
deaninq the safety aspects preceding an internal inspection are very
important, ft tank should be emptied of liauid, freed of gases, cleaned or
decontaminated, if necessary. Respiratory protection should be provided for
persons entering a tank. Severs! types of respiratory protection are
available, rancina from highly protective self-contained breathing apparat 's
to less-protective self-contained breathing apparatus to less-protective,
air-purifying respirators. A complete discussion of safety procedures for
internal tank inspection? is beyond the scope of this manual. Persons not
experienced in the conduct of internal tank inspections should contact the
Occupational Safety and Health Administation for assistance in establishing
safety procedures.
Adequate lighting must be provided inside a tank for a safe and effective
in$DPCt^o*". "'"He roof and iiterrai s'jr-DO'-ts shou1d be inspected f i"s* , V
followed by a preliminary visual inspection of the tank shell, to ensure that
the tank is structurally stable.
Roof and Structural MembersA visual inspection of the roof interior
usually suffices. Thickness measurements should be performed, however, when
corrosion is evident. Special attention should be given to interior roof
seals.
Tank Shell--The she1! should be examined for visual corrosion. Tank
shell thickness should be measured at representative points to ensure that
thickness is maintained. While the bottom, the roof, and especially the shell
are being inspected for corrosion, the plate joints and the nozzle connection
joints should be inspected for cracking. If any cracking is found, a more
thorough investigation by magnetic-particle, penetrant-dye, or radiographic
methods may be needed.
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11-23
When the inside surfaces of a tank are lined with corrosion-resistant
material, it is important to check for holes or cracks. Scraping or dye
penetration is effective for locating pinholes and tight cracks. Bulges in a
lining indicate leakaqe behind the lining and possible lining deterioration.
Tank BottomTank bottoms should be hammered thoroughly tc detect
corrosion pits and SP"-." c seams, ^ammeri^c should generally not be pe^ormed
in the area around a leak, in an area suspected to be extremely thin, on
equipment in caustic service, or on a brittle material. Radiography and
ultrasonic testing methods can be used as an alternative to hanmering in areas
around a leak or in a"eas expected of being extremely thin. These testing
methods are normally more accurate than harrmer testing. The rivets should be
checked at random for tightness and corrosion. The depressions in the bottom
and the areas around or under roof supports and pipecoil supports should also
be checke ~ v is u;11v.
*
11.1.5.1.4 Visual Inspection of Pipes, Valves, Mttings & Hoses
Inspection of pipes, valves, fittings and hoses are critical in detecting
losses in metal thickness owing to external or internal deterioration. In
many cases high liauid turbulence or velocity causes these equipment parts to
erode or wear. Leaks are most likely to occu" around pipe bends, elbows, tees
and other restrictions such as orifice plates and throttling valves. Loadinq
and/or unloadina hoses used as flexible connections between vehicles and
storage tanks are vulnerable to wear and tea" as well. Tank vehicles rcr-,irg
over hoses during loading and unloading can also contribute considerably tc
hose deterioration.
Visual inspection while the tank is in operation should include checking
the following:
(1) leaks;
( 2) misal i gnTent;
(3) unsound pipina supports;
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(4) vibration or swayinq;
(5) indications of pipe fouling;
(6) external corrosion; and
(7) accumulations of corrosive liquids.
Specific areas that should he checked for the above conditions includ°:
o pipe bends
o elbows
o tees
o orifice plates
o throttling valves
o loadino/unloading hoses
I'1 t"as on ic o" "ad" o?:t; ve test'rc te<~hniau
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Pressure tests for pipes may include a design test for newly installed
systems and a leakaae and tightness test for existing systems. Leaks are
detected through failure of the pipe to contain the pressurizing medium
(steam, air, water, carbon dioxide or other inert gas). The roost popular
medium for pressure tests is water. All piping seams should be soaped prior
to pressurizing. Bubble formation indicates leakage.
Use of compressible or condensible gases such as steam, air carbon
dioxide etc. are generally less reliable. More reliance should be placed OP
listening for the sound of escaping gas or otherwise detecting leaks.
11.1.5.1.5 Inspection of Pumps and Compressors
Although mec^a^ical wear is the primary cause of deterioration for
p;jTir-a anc4 compress *o- erin oment , erosion and corrosion can also he a
contributing factor in deterioration. Improper operating conditions, pip-fng
stresses, cavitation and foundation deterioration causing misalignment, have
been known to contribute to deterioration as well.
Routine visua1 inspections of pu^ps and compressions should include the
followina areas:
o Foundation cracks and uneven settlina.
o Lea^v pump seals,
o Miss ing anchor bolts,
o Leaky piping connections,
o Excessive corrosion,
o Excessive vibrations and noise,
o Deterioration of insulation,
o Excessive dirt,
o A burning odor or smoke,
o Missing safety equipment such as a pump coupling guard,
o Repleted lubricaticr oil reservoir.
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n-?6
Vibration has been known to rapidly deteriorate a pump or compressor therefore
periodic inspection of the vibration level should be conducted by usina an
electronic vibration meter. All assembly bolts, gaskets, cover plates and
flanges should be inspected as well to detect leaks and cracks.
Concernina inspection convenience, two puTips are often installed ^n
parallel such that one pump may be shut down wnile the other performs the
reouired pumping. This makes possible complete internal inspection or
replacement of one pump while the system remains in operation.
When a pump or compressor is taken out of service the mechanical
components should be checked for clearance, corrosion, erosion, deformation,
wear and any other changes detrimental to safe operation. Manufacturer's
recommendations should be followed during disassembly.
11.1.5.1.5 Heat E*c^
Deterioration may be expected on all surfaces of exchangers and
condensers that contact chemicals, water (both salt and fresh), and steam.
The form of attack may be ele:trochemical , chemical, mechanical, or a
combination o* the three types. The attack may be further influenced by
accelerating factors such as temperature, stress, fatigue, vibratior,
impingement, and hi an flow velocity.
Appurtenant ite^s to exchange-s and condensers sucn as lac^e^s,
platforms, foundations, pipe connections, paint, and insulation can he
inspected visually in a manner analogous to the inspection of a tank. The
exchanger or condenser itself can be visually inspected for rust spots and
blisters. If a unit is out of service, inspection procedures can be more
detailed. A scraper and a ball-peen hammer can be used in conjunction with a
visual inspection to detect areas subject to excessive erosion and corrosion.
A pressure test utilizing a test fluid can also be used to detect leaks or
excessive erosion or pitting.
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11-27
11.1.5.1.7 Inspection of Vapor Control Systems
Some systems employ the use of a vapor holding tank. Vapor control
systems are most commonly used in tanks that hold high coefficiency of
expansion liauids. If tanks are not filled to capacity in most cases,
sufficient head space exists so vapor control systems are not necessa'-v. *\
valves may be useful however in emergency situations.
Areas of inspection should include the following:
o The pressure release valve which should be examined for clear
1 ines.
o The bladder height gauge, which should be inspected for prope"
working conditions.
o The a^ea betwee^ the hladde1" and shell should be checked w^t^
o The cycling schedule should be monitored to deterime if the
system is in prope-" operating condition.
The bladder height gauge and the pressure release valve are usually located on
the roof of the holding tank.
11.1.5.1.8 Inspection Tools & Electromechanical Equipment
When visual inspect > o^ necessitates a more detailed inspection, siT'ne
hand tools may be used as an initial aid. Scrapers, diggers or f, ana-
spreaders are adeguate for these purposes. Hammers, mirrors, magnifiers,
magnets and plumbing tools may also be helpful.
When the inspection necessitates more sophisticated equipment, mechanical
measuring tools or electrical devices may be used. Mechanical measuring tools
include measuring tapes, scales, micrometers, calipers and wire gauges.
Useful ultrasonic devices include ultrasonic and electromagnetic instruments,
which provide nondestructive means of determining wall thickness.
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ft- h^
11-28
Chemical examination and destructive test methods may be employed, as
well, to evaluate performance of storage system components. Destructive test
usually refers to cutting coupons, small plate sections, out of the tank base
to test for corrosion on underside of tank bottom. Destructive tests are most
often used with empty, aboveground tanks. They are not commonly used with
underground, althouah they couV be. Destructive tests and cherr.-. ca"
examination are useful in providing detailed performance data at either the
macroscopic or microscopic levels, depending upon the the choice of
examination technique.
Destructive testing typically involves taking a sample of a tank or pipe
wall, welded, etc. for detailed inspections and analysis, often under
laboratory conditions.
rhe~iC}^ ex^min5f:nn can involve either the followina:
»
o Spot testing in the field, where the reaction of a storage
system component to exposure to a specific chemical is usually
evaluated.
o Laboratory analysis, where a sample taken from the storage
facility is closely analyzed unde*- laboratory conditions.
The selection of a particular test method depends on the tyoe of tank to
be inspected, the extent of the inspection and the eouipme^t available.
'Several of the most co""^on advanced inspection methods t^at are mentioned
^t this sect-o S'-e described belo-. .
Penetrant dyes are often used to detect surface cracks on the outside of
a tank that would not be revealed by a visual inspection. The penetrant is
applied to a cleaned and dried surface by either brushing or spraying. After
a few minutes of contact, a chemical developer is then sprayed onto the
surface to give a white appearance upon dyeing. The dye stains the developer
and exposes the extent and size of any defects.
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11-2Q
The magnetic particle method is also used to define surface cracks on a
tank. The tanks surface must be carefully cleaned initially. Iron particles
are then sprinkled on the surface. A magnetic field is next imposed near the
particles, either by a permanent magnet (especially if flammable materials are
stored nearby) or an electromagnetic device. The iron particles then arrange
themselves along surface crocks, particularly near the ends of clacks. The
magnetic field should be imposes in two directions to ensure that tnere are no
cracks or to identify two or more cracks running in different directions. No
indication is given about the depth of cracks using this method. This method
may be used only on tan'*? constructed of magnetic materials.
The vacuu^ box is an open box in which the lips of the open side are
covered with a sponge rubber gasket, and the opposite side is glass. A vacuum
gauge and air siphon connect-'on are installed inside the box. The seam of a
tank shell is first w~tteH w'th a soa? solution, then the vacuum box is
»
pressed tigntlj o.e-- t e s~~~. ~re
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n-30
Radiography is used to detect flaws such as cracks, and voids, in opaque
(solid) materials. Radiography ma,y also be employed in determining wall
thickness, product build-up, blockage, and the condition of internal equipment
such as trays, valve parts, thermowel Is, and the like.
The radiograph k tec1-.ricue uses either X-rays o-- gamma radiation. T|^e
two rays are similar. The X-ray is produced in a tube within an X-ray
machine; the gamna ray is produced f*-om a radioactive material contained in a
small capsule.
Radiography testing can only be conducted by Qualified radiographers.
Specific precautions must be taken when the"e is the possibility of exposure
to X-rays or gamna rays. Training and experience are required to correctly
interpret the i^aoes produced on radiographic film.
Otne" RaC-iafO'.-ty:.'- l^st- jrr.g-ts :^:! as ria''ic po-ter'e ge^r; r<3.r
instruments may also be used to radiograph materials for defects. These
instruments are particularly adaptable to measuring piping and, to a lesser
extent, vessel-wall thicknesses. ^s mentioned, considerable experience is
required to operate radiation-type instruments proficiently and safely.
Acoustic Emissions Testing employs piezoelectric transducers to mon-ito-
the acoustic emissions given off by a material during corrosion or
d isbc"-;T: . Essentially t^is technique involves "listening" to detect the
pressure of corrosion or other stressful situations in a structure, /coustic
emissions testing can be used for the following purposes:
o detection and location of flaws in structures
o leak detection and location
o corrosion detection and location
o real-time detection and location of flaws during welding U
operations
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11-31
11.1.5.1.9 Secondary Containment
Freouency of internal inspections of tanks need not he overly excessive
if a tank operates at near atmospheric pressure, and contains hazardous
materials that are not maiorlv threatenina to human health and environment.*/
More freauent inspection schedules may be needed, of course, if the material
that is storec is hiahly volatile, toxic upon inhalation or hiahly reactive
with the material of construction used for the containment system. The
quantity of the material which might be leaked to the secondary containment
system and the decree of difficulty involved in cleanina up a spill, must both
be considered as well in determinina inspection freauencies . Nonetheless
freauent external inspections to detect leaks are highly recommended. TA11 in
all the more freauent the extema1 inspections to detect leaks the better.!
Because it is so difficult to detect leaks in insulated tanks, reliance on
secondsrv cont = inrr'c"''' aT* osri^ "l^st- {jptocti1"^ is not 5 ^
External inspections are impossible in cases where tank bottoms sit
directly on a foundation which sit within a secondary containment system.
Because external inspections cannot he relied upon for leak detection in this
case the permit applicant/writer should -be aware that pittina or other forms
of non-unifoi~" corrosion ^ y occur on the tank bottom resultino in leaks beino
^discovered for an extended period of time. Tests other than external
inspections should he
Any possiKiiitv of . incompa ti b i 1 e wastes mixino in tne same secondary
containment area must be avoided. Finally, possible ignition of hazardous
waste, if combustible when in the secondary containment system, must be
avoided. Such things as motor vehicles must be kept out of the aeneral area.
V Source: Permit Writer's Guidance Manual for Hazardous Waste Tanks, for
U.S.E.P.A., by Batten?.
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11 - 32
11.1.5.1.10 Frequency of Inspections
Inspection intervals at which various inspection procedures should be
performed are mainly site specific. Because of larqe dissimilarities in
sto^aoe conditions it is difficult to stipulate riaid inspection freauencies.
Inspection intervals. for a tan', and its eouipment should be based on the
following considerations:
o Results 0^ previous visual/maintenance inspections
o Tank location
o Potential risks of air or water pollution
o Potential risk for personnel injury or risk to human heait^ and
the environment
p £ V 5 i i aS in i t- y r^ t -i p ^ pp (-t i nn PO u ^ D""1 or t
o Materials of construction, corrosion allowance, chemical nature
of the material beinq stored, and known or expected corrosion
rates.
External components of a storage system can be easily and routinely
inspected throuoh visual observations or simple mechanical check?. The
results of these maintenance c^ec
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11-33
devices and other appurtenances. A more thorough inspection of external tank
surfaces, welds, rivets, and foundations should be undertaken on a monthly
basis.
In contrast, internal inspections must he performed when a tank and its
associated equipment a>-e ' emptied a^d out of service. Necessarily these more
detailed inspections are performed less freauently. However, if a tan'* shows
signs of corrosion or leaking due to cracks or holes, it should be taken out
of service for immediate inspection and repair. Also if a tank's material of
construction is beina corroded rapidly by the stored product, the contents
should be transferred to a corrosion-resistant tank.
11.1.5.1.11 Fiberglass Qe^O'-ced Plastic (P?P) Tanks
Cprrosipr is the r-si^v ca'ise of failure in reta1 tan^s. ^SP tanks,
nov;evtr, c' c rrore <>-e', to *6'" c^~ to re6:ViOr;, softeninc, s*e"ing 'or
cracking than from wall corrosion.
Abovearound reinforced plastic tanks should be inspected for cracking due
to bendina, curvina or flexina after delivery and throughout the service of
the tan''. Excess pressure car result in structural failure evidenced by
interior 1 onai tudin al crackina in horizontal tanks and by vertical cracking in
vertical tanks. The dye penetrant testina method can be used to further
' investi a*te susnected
The interior lining or coating of the tank should also be inspected for
signs of decomposition resulting from chemical attack. Dish tank heads or
ends and nozzles and gussets, if accessible, should also be carefully checked
for potential weak points.
Concerning freauency of inspection, FRP tanks have not been in use for a
long period of time, therefore, the best recommendation for frequency of
inspection may be the tant- manufacturer. In addition, parties such as certain
chemical manufacturers that have used the same or similar plastic T
-------
formulation for the corrosion harrier to contain similar liquids miaht be a
good source for guidance on freauency of inspection. The permit applicant for
an FRP tank miaht incorporate such information from the manufacturer in the
permit application.
If the plastic that is used is not affected by the hazardous waste that
is stored, relatively lone inspection periods are acceptable. Service life
under these conditions mio^t be indefinite. When significant deterioration is
apparent the tank should either be removed from service or repaired. Extema1
inspection of FRP tanks is not effective in determining the condition of the
interior. Therefore detailed external inspections will qive no indication as
to necessary freauency of interne! inspections as they might with metal
tanks.
Concrete is used primarily in large open tanks and treatment basins. In
conducting inspections and determining inspection freauencies for concrete
tanks, several characteristics of concrete must be considered. These are
1 is ted be! ow:
o Concrete is susceotable to f reeze-thav, cracking and
dpteri orat ion if not properly air entrained.
o If net fade v. 'tn sulfate -res istant cement, concrete is subject
tc ?.tt?.c- b , -r = -ly a11 si/'rte sa^ts.
o Concrete is susceptible to attack by many chemicals including
alum, chlorine, ferric chloride, sodium bisulphate, sulfuric
acid and sodium hdroxide ( 20 percent).
o Concrete may be permeable to some liauids.
The Anerican Concrete Institute (ACI) Manual of Concrete Inspection
includes information on inspections fundamentals, testing of materials,
sampling and inspection before, during and after concreting.*
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11 - 35
11.2 MAJOR ISSUE POINTS
1. Are all eauip^ent, devices and structures associated with overfill
control systems identified for inspection?
2. Is a schedjip and procedure for inspectina the overfill contro1
syste~ and re-, i tor in q eauipment for all tanks provided in the permit
aopl ication?
3. Are all eauipment and structures identified for daily visua1
inspection of abovearound portions of the tank?
4. Are specific parts of the eauipment and structure identified in
detail for daily visua1 inspection of abovearound portions of the
5. Are construction materials identified for weekly inspection of
externally accessible portion of the
6. Are secondary containment system's identified for weekly inspect^1"
of the externally accessible portion of the tank?
7. Are sDecific parts of the secondary containment systems identified
for wee'-ly inspection of the externally accessible portion of the
tank?
8. Has the procedure for collectina monitorina and leak detection data
been identified for daily visual inspection?
*5ource: ACI Wanua1 of Concrete Inspection, Publication SP-2, 1981.
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9. Are all specific parts of the equipment and structures associated
with the cathodic protection systems identified in detail for the
reauired freauency of inspections?
Have specific components and operations of impressed current
systems been identi'ie'J for monthly inspection?
Have all specific parts of the anode output of a sacr i^icie"1
anode system been identified for semiannual inspection?
Has the tank system-to-soii potential measurement task been
identified for annual inspection?
10. Are all eou'ipnner>t , devices and structures identified that will be
insPcctet' fp*' the as^ess^e't of the overall concition of the tank?
11. Have specific parts of the devices, eauipment and structures been
identified in detail that will be inspected for the assessment of
the overall condition of the tank?
12. Has a schedule and procedj^e for assessing the overall condit^o" of
the tan'" svstem been clearly indicated ; r t^e perm-'t apo1 icatior "
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12-1
12.0 RESPONSE TO AND DISPOSITION OF LEAKING OR UNFIT-FOR-USE TANK SYSTEM
12.1 REGULATORY CITATION
Information on the Continaency Plan and Emergency Procedures must be
included in Part B of the permit application, as specified in:
"§270.14(5) (7). A copy of the contingency plan required by Part
264, Subpart 0."
6264.196 Response to and disposition of leaking or unfit-for-use tank systems.
As part of the continaencv plan the owner or operator must specify
procedures for responding to spills or leakage from tank systems includina
procedures for expeditious removal of leaked or spilled waste. These
procedures m.ist be available for review by EPA upon reouest and must include:
»
(1) measures for containina any visible contamination;
(2) measures for immediate removal of waste from the tank and
containment systems;
(?) procedures for conductinc assessments of the risk to human
health and the environment and the remedial actions necessary
to mitigate the severity of a release;
(4) the owner or operator must promptly, in accordance with the
procedures set forth in the continaencv plan, remedy any
malfunction, deterioration, lea^, spill, or crack.
(5) a certification by a qualified registered professional engineer
that a tank system, prior to its return to service, is capable
of handling hazardous waste for the intended life of the tank
system without permitting its release into the environment.
12.1.1 Guidance to Achieve the Standard for the Contingency Plan
12.1.1.1 General
The Permit Writer's Guidance Document to General Facility Standards,
Section 5.7, contains procedural requirements for implementing remedial action
in the _.-_ >. . u _--i1!, lea'--, or other urintended rPiea?e Of Wsste? fro- a
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12-2
tank storage system. Tank owners must initiate prompt, effective action to
contain, recover, mitiqate, and remediate any release which poses a threat to
human health or the environment.
The contingency plan reduced under Suboart D of Part ?6d must include a
description of procedures to be followed in responding to soills or leaks,
includinq the timing and procedures for the removal of leaked or spilled
waste, removal of waste from secondary containment systems, where applicable,
and measures that will be taken to minimize any further release. The
contingency plan must be made available upon reauest of the Agency.
At a minimum, these procedures must include measures for the containment
of releases, measures for removal of releases from the environment surrounding
the tank systerr and fron- the containment area, if applicable. Procedures for
assessina the risks to hu^ar. heaHh and the environment and remedial actions
which will be effective in mitigating the severity of a release must be
addressed. Procedures for certifying that the tank system will not permit
releases after being again placed ir service must be addressed.
The intent of Pa^t 264.196 is, to outline those response procedures and
remedial efforts which will most effectively reduce the potential damaae
caused by an unintentional release, and to mitigate ootential health or
environmental damaaes.
It should be emphasized that there is no single resoonse procedure that
will suit every leak situation, and the tank owner may be forced to exercise
considerable ingenuity and judgement in applying effective mitigation
techniaues. However, there are standard concepts for responding to spills or
leaks with which the applicant should be familiar.
Permit applicants and writers should refer to the American Petroleum
Institute's publication 1628, Underground Spill Cleanup Manual for a better
understanding of the comolexities of remedial actions with underground spills
or leakage.
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12-3
Response to a waste spill or leak will include a number of standard
considerations.
o Assessment of the nature and condition of the release; site
investiaation;
o Reportina the release;
o Decidino upon effective steps to contain and mitigate the
effects of the release, and to recover released wastes;
o Takina the defective tank system out of service to preclude
furthe" leakaae.
While each incident will have characteristics unique to the
circumstances, these general principles will apply. Special operational
techniques reauired wi"11 be based on local conditions.
;,.ir,c $=:'-": i Crte'.l so~e c- t-ie ^^"or-atior which sho^"c be
included in the continoency plan.
12.1.1.2 Investigation
Before atte~'Dtinc to initiate remedial action, the tank owner must make a
careful assessment of conditions surroundina the release. If the spill or
leak is aboveground and readily accessible, prompt action to contain and
recover spilled waste n»y readily resolve the proble^. If, however, the
release is undera-'ound, an involved and extensive investigation may be
required to identify the pattern of release. Complex remedial efforts may be
required to effect recovery.
In either case, response should be planned, coordinated, and suited to
the circumstances of the case. Investigation should provide the following
information;
o Source of leak or spill
o Nature of Bastes spilled
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12-4
o Volume of wastes spilled
o Pathway or potential pathways
o Receptors and risks to health or environment
o Extent of spill area
o Flo* harriers of spilled wastes
o Availability of materials and resources to mitigate spill effects
The time reauired to investigate an aboveqround spill is usually
relatively short and the reauired effort is minimal. The conditions a^e
usually self-evident, and remedial operations straightforward.
Underaround leakaqe, on the other hand, may require extensive
investigation to determine the nature and extent of the problem. The tank
owner must often employ relatively complex and sophisticated techniques to
examine the soil sur^ou^dinc the lea^ a'-ea, and identify leakaqe pathways.
The type of soil, its permeability, qroundwater levels and slope, and possible
receptors must be determined. Well water samples and representative soil
borings will often need to be examined in the laboratory.
The site investiaation should be carried out by individuals knowledaeahle
in hydrogeolooy and soil mechanics. The person performinq the investigation
should have t^e followinq equipment available:
o Expiosimeter
o Flashliqht
o Hand Tools (pliers, screwdriver, hammer, etc.)
o Tape Measure
o Product Sample Thief
o Cord or Spool of Heavy String
o Carpenter's Marking Crayon
o Clean Sample Cans, Tags, Report Forms
o Clean Glass Jars
o Rubber Boots, Gloves, Field Clothing
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12-5
o Camera and Film
o Notebook, Plottina Paper, Writing Surface
o Carpenter's Level
o First Aid Kit
o Fire Ext inauisher
o Flares
He should have access to a transit and surveyors rod for measuring
elevations on the water table, or should ensure that a contractor is hired to
provide this service
A diary of events should be started, and all data loqaed as obtained.
Diary entries should be clear, concise, in notebook form, dated, and sianed.
ts sooi as possible, contact anv oe-so^ familiar with the circumstances
and review the reported details. Inspect the area for visual evidence of
leaks. Use an explosimeter to attempt to locate vapor concentrations.
Attempt to identify the source, if possible. Look for obvious evidence of
spillaoe near the tank system and its ancillary equipment.
Examine the area in the aeneral vicinity, locating wells,
systems, watersheds, wetlands, or possible areas for contamination. Consider
the need for absorbents, disoersants, or flow barriers if the surrounding area
is exposed to contamination.
Obtain plot plans and construction plans of the property. If possible,
locate geodetic maps of the area. Identify locations of underground piping,
sewer drains, sanitary or storm drain systems, electrical service lines, any
sumps, manholes, catch basins or similar traps in the area. Attempt to
determine the geological make-up of the subsurface soil in the area. Contact
the local Public Works Department for advice and information about the
neighborhood. Prepare field sketches of the site for later use as
worksheets. Review a^v available inventory records in an attempt to estimate
the amount of leaked waste.
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12-fi
Notify the local officials, such as fire department, health,
environmental, or others as required by regulations, and advise them as to
conditions and plans for action as soon as the scope of the problem has been
evaluated.
Identify the location of all tanks in the area, includinq residential and
commercial. Audit the accuracy of inventory records, review delivery
information, note frequency of deliveries, observe operator's gauqing
practice, and review any other handlinq procedures which miaht affect the
accuracy of accounting records. Note the tank locations, sizes, manifolding,
and piping configuration, together with waste assioment. Observe pumping
eauipment, both for receipt and handlinq.
Where the^e is more than one tank and vapors have been reported in nearby
b'jiicMnas, it mav be necessary to test the tanks for tiahtness. This should
be done promptly. If a defective tank is identified by testina, empty that
tank and, if possible, place probe holes in the water table between the tank
location and the fumes area. This may confirm if there has been waste
migration towards the impacted buildinq.
Observation borincs, or probes, are an important aspect of investiaation,
and will be frequently reauired in underground leak cases. It is preferable
to have the contractor use a small diameter bo*"inq tool, or auger drill, (£
inch is considered most useful), rather than attempting to dia to the water
table with a backhoe or similar larqe excavation tool. Contract with a soil
boring contractor or well driller for this work.
If possible, it is important to determine the groundwater elevation and
slope as soon as possible. Elevations of the water table should be
established from a known benchmark, using the probe holes and a slot made
showing the slope of qroundwater in the vicinity of the tanks. Contact with
local Public Works or the Coast and Geodetic Survey office will be helpful in
determining the rise and fall of water table levels, and any known chances in
pitch. With this information, and knowing the nature of the subsurface soil
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12-7
structure, some estimate can be made of possible direction and rate of flow of
waste migration. With an estimate of lost volume from operator records, it
may then be possible to evaluate the circumstances and begin planning remedial
action.
If the possibility exists that sufficient waste has been lost underaround
to justify subsurface exploration, proceed as follows:
1. Call the County or City Surveyor for advice as to the
groundwater elevation; slope and soil information. Locate the
nearest body of surface water. After establishing a series of
observation borings, take elevations on the water table to
define its gradient precisely.
2. Locate observation wells near the spill area, as much
out-of-the-way as possible. Install both uporadient and
downaradient wells so that the significance of the
co^ts^ina4: ion can be assessed. Refer to Chanter 8 of this
"la1";-;" *C"~ err1 1 ic1" £" ojidance ar- references. f"iirtne:- from
the spill area, the spacina interval may increase. Actual
location and density are dependent on the availability of
suitable sites.
3. Locate, first, observation borings as near the spill site as
possible. If doubtful as to direction of spill movement, drill
on all sides. Holes
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12-8
7. Run elevations on all wel'ls, locating the elevation point at
the top of each casing. Record the data on a plot plant of the
observation area.
8. If the amount of waste observed or calculated indicates need
for a recovery effort, plan and install an appropriate system.
Seek expert help at this point. Methods of recovery have
become extremely complex utilizing sophisticated procedures.
In c sionificant spill, it is recommended that the owner not
unde-take cleanup efforts unless he has had past experience.
Conclusions drawn from field investigations should be carefully
assessed. Corrective action should be based on compliance with local
regulations, cost effectiveness, and practicality. Many state or county
environmental agencies have developed special expertise in recovery
techniques, and can be very helpful in planning an effective prog^ar".
12.1 .1 .3 Reporting
»
Any release of a hazardous substance that exceeds the reportable quantity
established under 66l03(a) and (b) of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA) must be reported to
the National Response Center f l-(800)-424-8802l within 24 hours of discovery.
The reportable quantities are liste;d in 40 CFR 302 and were published in
Federal Register Vo1 . 50, No. 65 on April 4,
12.1 .1 .4 Re^e^a1 AC tip"; Surface Spill
The extent of abovearound spills and leaks is usually readily evident and
remedial action plans are often simple and straightforward.
The most imprtant response to abovearound spills is to stop the flow and
contain the escaped waste in an area where it can be recovered. Speed is
usually essential in erecting barriers to flow and placing containment
equipment.
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12-9
A surface spill may permeate the soil and involve both surface and
subsurface remedial efforts. Surface spillage may also miqrate to manholes,
drain lines, basements or wetlands. If the waste contains iqnitable or
reactive constituents, a fire hazard may be created. Response planning should
address these concerns.
If recovery efforts can be started immediately following the spill, there
is a good chance of capturing most of the loss. Every effort should be made
to block the flow path closing off channels into open catchbasins, gutters,
or sloping surfaces leading down and away from the spill site. As quickly as
possible the soil! should be contained with whatever flow barriers can be set
UD . Check the wind direction and soeed; position barriers on the downwind
side.
Wha>-p the volume cf lost waste "? s^all, and can be safely dispersed o\;er
a wide area, evaporation may resolve the program. However, sources of
ignition must be kept away, and careful watch over possible travel of vapors
will be necessary until the danger is passed. A water hose may be a useful
tool to direct the waste to a containment location; care should be exercised
that it is not flushed into catchbasins or sewer lines.
If a large volume is involved, and can be contained, absorbent bags or
pads should be obtained f<-om a pollution control contractor or supplier. Hay
or straw is a"1 so useful, if readily available. Maintain oood ventilation, and
check for vapors in the surroundina enclosed area. Use of chemical
dispersants may be considered, but local environmental agency, Coast Guard, or
EPA approval is usually required before their application.
If the spill has migrated to wetlands or streams nearby, a competent
spill contractor should be called in to commence containment and recovery
efforts .
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12-10
Where the surface soil has become saturated with ignitable liquids,
digqing should be conducted with extreme care to avoid sparking from stones
and ignition of the waste. Equipment should operate slowly, with due reqa>-d
for the danger of explosion in these hiqh vapor-content sections. There are
special rubber tips for backhoe shovel teeth available for protection aaainst
sparks. In certain circumstances., moving the earth may ventilate the
saturation area sufficiently to relieve the vapor concentration, allowing
movement and activity to proceed safely.
If required, removal of the saturated soil must be transported to
authorized storage or disposal sites, with due regard to hazardous waste
disposal reflations.
During the course of attemptinq to correct problems presented by a
surface soills, the owner should insoect the surroundinq area, the waterways,
arainage channels, and wetlands. Particular attention must be given to
preventing waste incursion into these sections. Collection ditches,
interception trenches, or curtains, or plastic sheeting should be considered
for interrupting the flow of liquid. API publication 1628 describes the
migration of petroleum product in soil and groundwater and suqaests a number
of techniques for entrapment and recovery of movina liquid.
Sometimes spilled waste will collect in a sump, pit or dry well. It must
be pumped from these open traps and disposed of by contractors properly
licensed under environmental regulations for the handlinq of volatile or
hazardous fluids. The disposal methods used must meet hazardous waste
disposal rules as to proper documentation and shipment to authorized storaae
sites. The methods of handling the liquid must follow safe operating
practices, since any exposed flammable fluid will present a serious fire
hazard.
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12-11
Pumping equipment for skimminq wastes which float on the water surface is
available. The equipment required will depend upon the depth of the sump, the
amount of product, its flow rate into the sump, and safety concerns.
Specially designed "skimmer" pump systems are available from spill control
contractors.
A system for separating light wastes and water may be required, where the
pump discharge is a mixture of both liquids. Under some conditions, the major
percentage of liquid pumped out will be water, which may be drained away from
the recovered waste. Typcally, light solvents and water will separate
readily; however, there may be emulsions formed due to impurities of dirt,
which will impede rapid separation. In this instance, some time maybe
required before clear water can be drained off. It will be necessary to
ensure that wate*" is drained to an approved discharge area. No entrained
wastes will !^e a''lov.e'J ^e^e the discharae is back into the soil, or into
v
storm drain systems. In setting up a drainage plan, make provisions for a
periodic sampling of the water effluent to monitor the presence of trace
amounts of wastes. Use of multiple stage settling sections and/or filtration
systems may be necessary to ensure complete removal of the waste portion of
liquid mixture.
Separate from the removal of water, another proaram must be developed for
the capture and storaae of the waste itself. Normally, a holding tank will be
required at the recovery site, into which the product from the separator--or
directly from the skimrnno pump--can be transferred. As the amount of waste
fills this tank, it can be trucked elsewhere for final disposition. Tank size
is usually determined by the nature of the problem. For small volume cases,
or slow recovery rates, a skid tank or small heating oil tank (275 gallons)
may suffice. At high volume recovery situations, tanks of up to 4000 gallons
capacity may be needed. Of course, the pump-out frequency of the holdina
tank will usually dictate how much on-site recovery storage is necessary.
Where existing underground tankage is available for storing the discharge,
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12-12
this may be used. Sometimes, in special cases, a tank truck may be kept in
place, and discharged waste pumped directly there. In all cases, the method
and storaqe of recovered waste must be approved.
Electrical service will be reouired for pumps and liahtino. Power
eauipment should be explosion-proof to preclude sparking near volatile fumes.
Be particularly careful about placina electrical machines at ground level
where vapors may move. (Some vapors, for example, being heavier than air,
will sink to the ground and travel downhill to collect against any barrier
which will stop further movement.) If gasoline powered pumping units a<*e
used, be sure they are located well away from any area where volatile fumes
may be generated.
To further ensure protection aaainst fire hazards, cover observation
wells, sumps, or rpcove-v wells an^ install vent pipina. The sump or well
i
diameter need only be laroe enouah to allow for the work to be done in them.
When pumps are operatina in these wells, the agitation created will cause the
fumes to rise, and lighter vapors may escape. Large open holes exposing a
wide area of volatile liquid should be avoided at all costs. Be sure to keep
all sources of ignition as far away as possible from the recovery site.
When planning a recovery operation, bear in mind that most volatile
liquids, and even small concentrations of vapors (often undetectable), oresent
a fire hazard if thev are near a source of ignition. Recovery fror
aboveground spills, or from large open holes, therefore, always includes
concern for safe handling to avoid fire or explosion.
In anticipation of possible aboveground spills, the owner should
stockpile an emergency supply of absorbent pads, containment boom sections,
and other response material that may prove useful if a surface spill or leak
OCCUrs.
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12-13
12.1.1.5 Remedial Action: Underground Leak
Unlike aboveground spill recovery programs, remediation of underground
leakage is often complex, and can vary widely in effectiveness.
A simple underaround waste recovery program may require only a drainaqe
sump installed at the water table level; seepaqe of the waste into the sump,
if located in a small surrounding area, may resolve the problem. This method
is low in cost, relatively effective for minor Quantities, but effective only
over a highly localized site. It also will probably require a long period of
time to clean up the spill, since the flow of waste through the soil is very
low, depending entirely on natural drainage. There is no way to control waste
migration away from the sump in the event of a change of water table, frost
line, or other condition.
>
Drainage trenches provide a somewhat more effective recovery mechanism
than the sump. These can be placed along the other edge of the spill area, on
the downhill flow side (when known), to trap a larger quantity of product.
Where the trench is of sufficient depth below the water table level, a sump
pump can be introduced to create more rapid flow into the trench than from
natural seepge, by removing groundwater. As waste accumulates, it can be
removed with a skimmer pump. Care must be exercised to ensure no su^p
discharqe of waste, and a separator system will normally be needed for the
waste reTOved. The trench must also be of sufficient length to guard aaainst
product flow abound the ends of the trench position.
Where the soil is relatively permeable, with good vertical percolation,
an effective technique involves building a shallow pond basin over the
affected area, and keeping it full of water. The water, seeping into the
soil, raises the level of subsurface groundwater, lifting any volatile liquids
floating on its surface. A series of recovery sumps located around the
periphery of this "mound" of localized water will receive the water flowing
down off the induced hiqher table. Control of waste movement is extremely
tricky, so this method should be used only with areat caution.
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12-14
All of these methods, however, are more-or-less static techniques,
relying on natural flow to collect the product. They are effective where a
sufficiently steep water table pitch exists to allow the waste to flow down
toward the recovery site. They are relatiely ineffective where a level water
table condition exists, and no horizontal flow occurs naturally.
In the level water table condition, a more positive method (a "dynamic"
method) of inducing waste flow roust be adopted. A deep well is constructed to
allow installation of a pump well below the qroundwater table level.
Operatinq this pump at a speed somewhat higher than the flow rate of
surrounding water into the well causes a "cone of depression" to be introduced
into the well, formina a "sink" into which wastes floating on the water table
will flow. In effect, this depression of the water level creates a
groundwater pitch toward the recovery well location, preventing waste
mi oration awav fro^ the Doping area. The flow induced into the recovery well ^
will continue as long as the core of depression remains, so this method
requires continuous pumpina. As the waste collects in the sump area, it can
be periodically withdrawn to a storage point of by a separate pump. As part
of the induced flow recovery program, a series of observation wells around the
recovery well location are usually necessary to measure the slope of the water
table, and to monitor the actual recovery of waste. The number and location
of these are determined by the nature of the specific situation.
Dynamic recovery techniques are highly specialized, required expert
advice, are usually very costly, but are often the only effective method of
ensuring acceptable recovery. The owner should seek expert help in a serious
leak situation, or where major waste losses endanger the enviroment of
community.
Recovery of underground spills are affected to a great degree by the
migration rate and direction of the waste restging on the water table. These _
are determined by the porosity of the soil, its composition, the pitch of the
water table, location of nearby open water areas, and a host of complicating
factors. The rate of movement is often measured in inches per day. Its
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12-15
direction may be erratic, affected by clay, ledge, sand, rock fissures, or
other obstructions. Soil analysis through borings, as well as water table
height and slope are always important in furnishing clues as to the extent of
movement and location of the existing plume. It is also important to
determine how lona the leakaae has been occurrino, as well as the amount
estimated to have been lost. Since remedial techniques are often more art
than science, the owner or operator should be prepared to experiment with
various methods offering some measure of effectiveness.
During the course of cleanup, samples of recovered waste should be
obtained for inspection and analysis. Hydrocarbons in the ground will appear
most cormonly mixed with water, so it is necessary to collect samples in a
manner by which much of the water can be drained away. In the field, the
simplest technique is to use a narrow-mouthed bottle to collect the mixture
directly fro^ t^e "ouddle" 0" pool of liauid. Allow the mixture to settle Jr
the bottle until the water has clearly dropped to the bottom section. Cap the
opening and tilt the bottle sideways until the wastes portion floats clear of
the mouth. Much of the water can then be drained away by simply uncapping the
opening while tilting the bottle. Repeat this procedure until sufficient
waste has been accumulated to provide an adequate quantity for analysis;
usually abojt a gallon will suffice. Put the sample into a clean container,
which will not react with the waste, with an inner cap seal. Ensure that the
outer cap is tightly sealed, and label the can with the date, place of
collection, na^e of waste, and any other description to clearly identify it.
Label lettering should be in large, bold letters written with indelible
marking crayon or paint. The sample container should not be re-opened until
in the hands of the laboratory.
An information sheet or sample reporting form (often furnished by the
laboratory) should be prepared to accompany the sample container. This form
should include which inspections as requested, and what general information
about the recovered product is desired from laboratory analysis. This will
normally include, for example, the type of waste, aae, manufacturer, and any
other description information which can further identify it and its possible
source.
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12-16
In those cases where the source is unknown, or of questionable oriqin, it
will be necessary to compare the characteristics of the sample with
representative samples drawn from all the tanks in the surrounding area.
Assistance from environmenta1 0" local enforcement authorities may be
necessary to ensure that samples are obtained from all sources.
12.1.1.6 Tanks Taken Out of Service
When a spill or leak occurs that has not clearly been caused by some
event other than tank failure (i.e., hose rupture during transfer, etc.), the
storaoe system must be taken out of service unitl the condition of the tank,
piping and appurtenances can be determined, to preclude further leakage. All
waste stored in the system must be transferred elsewhere and a test and
insoection
After transferring waste to alternative storage, the tank and piping
should be flushed thoroughly to remove "bottoms" or residual sludge (refer to
Chapter 14 for decontamination procedures). After cleaning, filling the
system with water will enable the owner to test the system for tightness usina
one of the underground tank test methods currently available.
If the tank system is found to be tight, and the source of leakaoe not
identified, the tank must remain out of service until the leak source is
determined, or plans made to upgrade the tank system as a preventive
measure.
If the tank is found to be defective, the owner must take action to
remedy the defect. This subject is discussed in more detail in 12.1.2.
While the tank system is out of service, the waste normally stored in it
must be temporarily retained in a storage system which meets the requirements
for the storaae of hazardous waste.
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12-17
Upon repair or replacement of the storage tank system, or the secondary
containment systems, the owner/operator must have the facility inspected by a
qualified professional engineer. The engineer must certify that the system is
capable of handling hazardous waste for the intended useful life of the tank
system without permittina its release into the environment. At least seven
(7) days before placing the system back in service, this certification must be
submitted in writing to the Regional Administrator.
12.1.2 GUIDANCE TO ACHIEVE THE STANDARD FOR CORRECTIVE ACTION
12.1.2.1 General
When field investigation verifies that tank failure and leal-age has
occurred, some form of corrective action will be required to repair or replace
the tank, and to mitiqate the imkpact of leaking wastes.
Each situation is usually unique, requiring action decisions suitable to
the conditions discovered. However, there are some general gudelines which
will probably apply to most cases:
o Where .aqe, similarity of tanks, and nature of failure indicate
th probable early failure of other tanks in the same system,
all tanks at the affected site should receive the same repair
or replacement action. Pipina and ancillary equipment should
also receive similar attention.
o Where the nature of the fai.lu-e and local regulations permit,
and where tanks are reasonably new, in-place repairs may prove
feasible, rather than more costly tank replacement.
o When tanks are replaced, non-corrosive or corrosion resistant
tank (fiber glass coated steel, doublewall steel, fiberglass,
cathodically protected, etc.) should be used.
o A single, unprotected steel tank should not be installed in the
presence of older steel tanks.
o A search for waste in the ground should be made whenever a tank
is repaired or replaced, regardless of whether the waste
leakage is confirmed.
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12-18
o Safe operation practices, fire protection equipment and fire
watch, if necessary, should be set up before any work is
begun. The owner should outline safety requirements to the
contractors, and supervise compliance.
Certain standard steps will apply in most cases, reqardless of the unique
nature of the incident:
o Make an inventory check to determine the estimated volume of
lost waste.
o Empty the defective tank of waste as ^oon as possible; isolate
it from service; isolate the pipina.
o Arrange for cleanup service, temporary storage of recovered
waste, and hauling recovered waste to autrhorized storage or
disposal facilties.
o Qualified maintenance contractors should be employed for
excavation, tank and pipinq repairs. Do not use general
contractor unfarr-i 1 ia>- witn the specialized nature of workinc
around volatile or hazardous materials.
o Provide pumping and spill containment equipment.
o Notify public safety and environment officials, where
appropriate.
In those cases where a hazardous condition clearly exists, first strive
to reduce the danger. Explosive fines, free flowing waste, or saturated soil
where excavation work is underway, are examples of emergency conditions where
no time can be lost in stabilizing the situstion. All necessary contractor
and public safety assistance should be called in promptly. Containment of
waste, ventilation of fumes, and removal of waste from defective tankage,
should be top priority actions. Further investigation and corrective
activities can then proceed in an orderly fashion.
In most situations, there are three alternatives available when a tank
fails:
1. Remove and replace the tank.
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12-19
2. Repair the tank in place with an inert resin or epoxy lining on
the internal surface. Installation of an impressed current
cathodic protection system to eliminate external corrosion will
supplement the internal repair.
3. Closure of the tank in place in accordance with regulations;
empty of waste, and fill with an inert material.
Removing the tank is often the best solution, dependino on specific
conditions, tank age, and the nature of the failure. It affords an
opportunity to improve the storage volumes as well as upgrading the storage
integrity. However, where existing storage may be relatively new, tanks are
generally sound, and there is no immediate incentive to replace them.
Repairing in-place offers a reliable, less costly technique of tank repair.
Closure is mo>-e or less a special case, in that it may apply most often to
sites where the activity is to be discontinued, or where storaoe is beina
replaced at another location on the property.
When the tank is removed, a search to locate migrated waste in and around
the tank hole should begin. Probing the area adjacent to the tanks should
reveal any leakage. A boring in the tank hole to the water table is important
before placing a new tank in the excavation. Take explosimeter readings at
manholes, catchbasins, sewer or water pipe runs nearby. Examine buildings or
neighboring structures or vapors. While there may be no positive evidence of
lost waste, take nothing for granted. Make a complete and thorough search of
the area.
12.1.2.2 Tank Replacement
When a single tank, in a multiple tank field, is to be replaced,
consideration must be given to the condition of the other tanks, and the
affect this replacement will have on the entire tank field. Whenever
feasible, all tanks should be replaced if they have been subject to the same
conditions of age and environment. Further, replacement tanks should be of
similar design and material to one another, although not necessarily of the
same capacity.
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12-?0
Where it is decided to replace only a part of a tank field with new
tankaoe, there are some considerations of importance. First, a new steel tank
in the presence of older steel will corrode at a faster rate than the existing
tanks. In the electrochemical activity of corrosion, the new tank surface is
more active (anodic) than the older tanks whose surfaces are Generally coated
with a thin rust or scale from having been in the soil for a long period. It
is not uncommon for new steel to develop corrosion damage within a very short
time, while the older tanks continue to remain tight. Another concern with
partially replacing tankage relates to the condition of all the tanks. Since
one tank in the installation has failed and assuming all other tanks are of
similar age and des ign--there is a hiah probability that the same fate awaits
the others in the nea^ future.
Sometimes a decision is made to replace a tank with one of different
design and material, such as steel and fiberglass. Unless careful attention
is given to the method of installation, serious problems can arise at a later
time. For example, if the fiberglass tank is not properly supported by
shoring or some form of positive retaining surface, any future exacavation
near the tank could cause a "rolling" effect, with subsequent major damaqe to
the tank. A slight movement could cause pipina cracks, from which waste could
escape undetected..
12.1.2.3 Internal Coating
A method of correcting a defective tank problem without removing the tank
involves coating the internal surface with a lining of non-corrosive
material. Normally, this should be considered only for newer tanks with
sufficient plate thickness remaining for long life. Applicators furnish a
warranty against tank failure after coating for up to 12 years. However, they
will reserve the right to examine the internal surface before coating, and
will refuse to service any tank failing to meet their standard of tank wall
integrity. Further, their warranty coverage extends only to repairing any
damaged coating, not to include incidental damage, such as leakage.
-------
The procedure involves entering the tank to apply a polyester resin or
expoxy material on the internal surface, leaving a non-porous, non-corrosive
coating. The technique is highly specialized; only contractors trained and
experienced in the procedure should be used. Many localities require prior
approval of the application method, and proof of contractor competence before
authorizing its use.
The tank, if not already open, is first cut open from the top with
non-sparking cutting tools, thoroughly vented with compressed air to a
non-explosive atmosphere, then entered for cleaning and inspection. If in
satisfactory condition, the interior surface is sand-blasted to white metal.
All corrosion holes are plugged with boiler plugs or self-tapping screws.
Fiberglass patches are applied to areas of critical damage. The interior is
then cleaned and dried thoroughly. A spray of either the resin or epoxy is
applied to a thickness of about 125 mils (1/d inch). The correct formulation
is developed premixed in the applicator's workshop trailer on the job site.
Upon completion, the tank cover plate is replaced, excavation backfilled,
asphalt yard patched, and the tank replaced in service. When epoxy material
is used, a curing period of 48 hours is required before putting waste in the
tank; the polyester resin is a fast-setting material, and can be used almost
at once following application. Consultation with tank lininq manufacturers
will be necessary toensure that lining material will be compatible with stored
wastes.
Of course, while the interior lining processing does not overcome
external corrosion, it does provide security against the effects of internal
corrosion. Installing an impressed current cathodic protection system will
provide external corrosion protection; so using both methods together may
provide a long-life retrofit if the lining is carefully chosen to be
compatible with both the tank interior and the waste.
When considering the use of this method, when one tank is to be lined,
all similar tanks in the same tank field should receive the same treatment.
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12-2?
12.? MAJOR ISSUE POINTS
Contingency plans for response to spills or leaks should emphasize:
o Prompt action to investiaate and take action to contain spiller!
waste .
o Careful assessments of the conditions surroundinq the spill or lea1
and of the potential hazard to human health and the environment.
o Prompt removal of waste in storage until its source is located.
o Application of effective remedial steps to mitigate the potential
hazards .
Remedial activities may require con-;. lex methods and techniques.
shoul d:
o Seek qualified, expert assistance.
o Be aware of safety ccns^ delations where waste may appea^.
o Seek to ensure maximum reduction in health and environmental
hazards .
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13-1
13.0 CLOSURE AND POST-CLOSURE PLAN
13.1 Regulatory Citation
Information on the closure and post-closure plan must he included in
Part P of the permit application, as specified ^n:
"5?70.^(b)f1"\ Cc?y o-f closure and post-closure plan;"
Part ?M subpe-t G sections 110-120 of the reflations specify the
reaulatory standards with which closure and post-closure plans must comply.
13.1.0 General-
The intent c* re:..T"ina suK~itt?"' of storaop tank closure and oost-closure
plar '-e:j -= "t".s . :; ' irie-:?- " ;-l'7". 1- ;b /; '2; v.'ih Pe"t E o^" t^e Der-ii
application is to supply adeauate information to accurately identify the
correct procedures to dose a storaae tank facility. There are several
options available for the temporary or permanent closure of reaulated
substances in storaae tanks. They are temporary closure, on-site or in-place
abandonment, and off-site disposal. This section defines these options and
presents the requlat^y crjide1ines for tank decontamination, storaae and
disposal as reauired in Part B closures/post-closures.
13.1.1 Reo'iletP'-v Citation
A description on the disposal or decontamination of equipment when closure
of the facility is complete must be included in Part B of the permit
application, as specified in:
"5264.114. Disposal or decontamination of equipment;"
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13-2
13.1.1.1 Guidance Tank System Decontamination/Removal Procedures-
Decontamination is the most critical task when permanently closing a
tank. The decontamination procedure should follow as a minimum:
0 Cleaning operations should be performed under the supervision of
persons who understand the hazardous potential of the o"iain?.i
liquids stored.
0 The personnel must be sufficiently skilled to safely perform the
decontamination operation.
0 Sludaes and residues should be removed from outside the tank and
be removed via non-sparkina eauipment, such as vacuum pumps or
trucks.
0 All contaminated materials removed from the facility should be
disposed of in a permitted secure treatment, storaoe or disposal
faci1 it v.
wate", steam cleanina or solvent washes.
0 For solvent washing, hian flesh point products such as mineral
spirits or kerosene are conronly used; aasoline should never be
used for this purpose. The residues from these cleaning process
must also he treated or disposed of properly.
Tank storao° systems which are permanently closed, may either be removed
from the at"cijrd or ahandoned in place.
?'1 ine 'Jn^e^oround Tar', s
1. Remove all hazardous waste from the tank and from all connecting
1ines.
2. Disconnect the suction, inlet, gauqe and vent lines.
3. Fill the tank and any remaining stubs completely with an approved M
non-shrinking inert solid material and cap all tank inlets and
outlets.
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i "3 ;
Abandoning Underground Tanks in Place (Sand -pumpina method)
1. Remove all hazardous waste fro^ the tank and from all connectina
lines.
?. Cut off ven>t lines ar^-oxidate"! v three feet above grade. (This
establishes an increased head on sand being pumped into the tank,
insuring complete fillinq of tank). Do not use cutting torch.
3. Disconnect and cap off extraction (suction) lines at dispense-'.
4. Make liouid-tioht threaded connections between fill lines of tank and
the discharge line fro^ sand pump. On tanks eauipped with fill pipes
extendinc below tank toe, it is necessary to remove the extension
p i D i n o within 13 n ' .
5. Attach a drain hose to the end of the vent line, by means of a tiaht
or threaded connection, and direct it into a reservoir (55-gallon
drums may be used) to hold any residual hazardous waste which miqht
be left in the tank.
P. Proceed to pump sand into tank until a dense suspension of sand in
water discharoes from vent lines. (At this point caps may be removed
fron extraction lines for observation.) Sand should be present here
before the pumping is stopned.
7. Caution should be observed in the area of the vent lines due to the
possible emission of flammable vapors. If necessary, conduct vapors
to a more remote or less hazardous area.
Preparation for Removal of Underground Tanks
1. Remove all hazardous waste from tank and from connectinq lines.
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2. Disconnect the suction, inlet, gauae, and vent lines; remove sections
of connect in- lines which are ret to he used further and cap or pluq
inlets, outlets and leaks, if any.
Disros al <~~f Tar1, c
Tanks to be disposed of as junk or sunp must be rendered free of hazardous
waste. No cuttino to^ch or other flame or spark-producing eauipment shall be
used until the tank has been completely purged or otherwise rendered safe.
Note: NFP/J No. 327, "Standard Procedures for Cleaning or Safeguardina
small Tank and Containers" provides information on safe
edure fo1" such operations.
13.1.2 Regulatory
be performed as specified in 6264. 114, then the Part B permit application is
specified in:
""$264.310, Closure and post-closure of landfills"
13.1.2.1 Guidance Sto^aae Tank Closure Considerations-
Permanent closure of underaround sto^aae tanks can be accomplished tv
either renovino tne ten'-- system o*~ abandoning the tank in pla:^. '>-'-
permanent closure of a tank system should follow procedures to prevent future
environmental hazards from occurring. Areas of concern during a tank removal
and/or in-place tank abandonment are as follows:
a. The extent of soil contamination must be determined to insure the
integrity of the site and to identify areas in which contaminated soils
need to be removed durinq closure.
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13-5
1. Test borings should be slant-drilled to intercept a point beneath the
center of the t ant.
2. For single tanks, a minimum of two test borings should be performed,
IdC^t0^ 0° rjnnn<;-it0 ^irlo? of thc tank S^onc thp rra i'0r 3 * ic Of t*~-
tani- .
3. For multiple tanks, borings should be placed at 20 foot intervals
around the tank cluster, at a minimum.
4. A Shelby tube or split spoon sampler should be used to take the soil
samples at denths o* p, 1°, 15, 20, 30 and 40 feet below grade level.
5. Analytical parameters for soil sampling should include, at a minimum,
tpc^c for th't*c- % pr
Classes o*' £?::: ~.c:e materials if tne tank syster co'Hainec ve'-iojs
types of wastes.
6. Soil samples should be placed in a refrigerated ice chest and
transported to a certified laboratory for analysis, using appropriate
methods. The results of the soil analysis will indicate whether
there is the presence of contamination in the soils below or
surroundina the tank system. The extent of soil contamination will
determine the volume of soil to be removed and disposed of in a
permitted secure t'-eat^ent, storaae and dispose1 facility
(T.S.D.F.).
b. If the selected facility is a certified landfill facility, that facility
must follow closure regulations to ensure it meets strict regulatory
criteria such as:
1. Placement of a secure final, cover designed and constructed to
minimize the migration of liouids through the closed landfill.
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13-6
2. The cover must be veaetated to promote drainage, minimize erosion,
o-^od: te spttlina and suu side-:?.
3. The cover should have a oermeability less than the natural subsoils
O " t ^ ° r"'tc.
£. The cove-" needs to function with a ninimur> of maintenance.
c. The secure land-Mil must also follow Post-Closure regulations such as:
1. Provide maintenance services to insure the integrity of the final
cover, repairina damaae to the cap as necessary.
2 . Maintain a^c rnritor the landfill leak detection system.
" irrCitc1 sv-lf" unii" lei:'-c*.r is no
lonaer observed.
4. Maintain and ronito1' the qroundwater monitorina system.
5. Insopct arc r5'>,ta-i^ rin-o° a^: ^unoff control systems tc o^eve^*
erosion cf t^e can.
6. Maintain surveyed land benchmarks.
13.1.3 Regulatory Citation
A description of the elements that must be included in a closure/
post-closure plan must be included with the Part B permit application as
specified in:
"S264.112, Closure plan."
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13-7
13.1.3.1 Guidance-
The current owner or operator of any facility that handled or stored
regulated substances must document their intended methods to close the portion
of the facility that manaaed the reonlated substances. The closure plan must
pi ve financial assurances to qua'-antee that all closure tas^s car he
accomplished. Copies of the approved closure plan must be kept at the
facility and all revisions to the plan are to be kept up to date until the
closure is completed and certified. The followinq items are to be included in
the closure plan:
0 Description of how and when the facility will be partially and
completely closed ;
SLCK6-- cl ariy tir-: cjrir- \-- both partial and final facility closure;
0 PreDa-e cost estimates fo" closure and post-closure care; and
0 Prepare a detailed description of the steps needed to decontaminate
the tank system and all related appurtenances and equipment dy-me
cl osu^e .
The dose of a tank system requires the current operators or owners to
remove or decontaminate all residue in the tank systems. The surrounding
soils, structural support systems, ancillary equipment and containment system
components must be tested to indicate the extent, if any, of contamination.
Any materials found to be contaminated with hazardous waste must be physically
removed from the facility or decontaminated following approved methods.
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13-'
13.1.4 Regulatory Citation
A description of the retirements for the closure of tank systems is
required in the Part B perrrit application, as specified in:
"$>? 6£. 11 2, Closure plan."
"5264.197, Tanks closure."
13.1.4 Guidance Tan.- Closure Considerations Precludina Secondary
Conts inirient
a. Important Concerns In Storage Tank System Closure
" ~n> sto'coe svste^s t?>en O'it of service must be D^ope-lv closed to
prec "-'>_ a nu~:er c enk i>-:- -e'.ls 'icZc^cs ro~ a-'oi^a, s
1. Any hazardous waste remaining in the tank will eventually leak out as
the tank deteriorates, possibly resulting in contamination of
soils, a^ounctaater or surface waters.
I
2. Accidental intrusion a^d release of hazardous waste to
environment may occu*" in the event of later construction, excavation,
or similar activities beiria carried on near the tank site.
3. Improper reuse of tankage may occur by individuals seeking to utilize
existing facilities without implementino the proper safeauards or
meeting regulatory requirements.
4. As abandoned underground tanks deteriorate, overhead traffic, heavy
loads, or construction activities may result in collapse of tank
walls. The resulting subsidence of the tank structure may affect m
nearby buildinas or surface activities, causing serious damage.
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13-9
5. Improperly closed or abandoned tanks containing hazardous waste
residue may pose an explosive threat. Accidental intrusion,
collapse, vandalism, or unauthorized entry may result in serious
injury or damage.
In order t:> insure that none of the potential damages or unsafe conditions
are allowed to develop, owners must properly close all tanks and ancillary
eauipment comprising the tank system. Such closure procedures may be based on
either a temporary withdrawal from service, or a permanent discontinuina of
use; each reauires specific steps applicable to the type of closure.
b. Temporary Tank System Closure
Where conditions reauire temporarily removing a tank system from use with
the inte^tio^ of returning it t^ service at a later time, the following steps
r.jst k>e take'.:
1. The contents of the tank system must be removed from tank, piping,
and all associated appurtenances. Sludge and "tank bottoms" should
be removed and disposed of in accordance with applicable regulations.
2. All pipina, including fill lines, gauging lines, and suction or
discharge lines must be disconnected and capped, except for vent
p i p i n c .
3. The vent piping should be left open to allow the tank to "breathe"
while out of service.
4. All electrical power to the tank system must be disconnected to
preclude inadvertent starting of pumps or dispensers.
5. Secure the tank system against tampering or unauthorized use by
laying a concrete filler in the fill and gauge boxes.
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13-10
6. Notify the appropriate reciulatory agencies of the temporary closure
in accordance with applicable reoulations.
c. Reuse of Tank Systems After Temporary Closure
Wr-,en the period of temporary closure is over, and the syste- is ao=-r-
placed in service, the tank owner should address a number of concerns rp"!atue
to reusing the tani system. The issues include:
1. If not done at time of closure, the tank system should be
cleaned of any remainina hazardous waste. Disposal of
material must be in accordance with applicable reaulations.
2. The reuse of the tani svste is based on the liouid-tioht
of t^e ta.n'«- svste"". £ ts'k system tiohtness test may be necessary t^
ins^-'i !=:. t-e syst-~ >s ir, acceptable concitior be*"c-e Deir:
replaced in service.
3. Where a different material than that previously stored is to be
placed in the tank syste^, the tank owner must insure that the syste^
is compatible with that rraterial. This is of particular concern with
fiberalass and FRD tanks where certain chemicals may not be
compatible with the epoxy or resin base material of the tank. This
may also apply in the case of steel tanks with internal epoxy linings
(i.e., alcohols may not be compatible with certain resins used in
older formulations of interior linino materials).
d. Permanent Closure of Tank Systems
When it has been determined to permanently discontinue the use of a tank
system, closure may be accomplished by either abandoninq the tank in place, or
by removing the entire tank system.
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13-11
The deterrrination of whether to abandon a tank In place or remove it for
reuse or disposal is dependent upon several factors, such as the aae and
condition of tank, its salvage value, and its potential for reuse. Local laws
and ordinances may require tank removal. Other factors that are important
include the followino:
Tank Location. The depth to which the tank is buried, the type of
soil in which it is buried, and overhead structures nearby will
affect the ease or ability to remove the tank. The potential for
damaae to concrete o- asphalt traffic surfaces and nearby utilities
should a^so be considered.
Projected Use of the Site After Closure. If site plans call for
development that involves excavation or rearadina to the leve"1 of the
tan'". it is likeiv tu>at the tank will have to be removed.
The Cost and Availability of Labor and Equipment. Tank removal will
require the use of heavy equipment and experienced labor. If the
cost or use of this labor and equipment are prohibitive, abandonment
in place may be the preferred option.
The proximity of Disposal Sites. The proximity of the disposal site
can also areatly affect the cost of tank remova1 . Tank
transportation costs could be prohibitive, making aban decent in
place the preferred option.
Regulatory Requirements. Local laws or ordinances may require
removal of the tank as part of any permanent closure procedures.
e. Abandonment In Place
Practices for abandonment in place, or on-site closure of underground
tanks, must include procedures for:
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13-1?
Removing all product.
Disconnecting all plumbing and controls.
Fillina the tank with an inert solid such as sand, oravel or
concrete. This is important to prevent subsidence of the around
abov° thp tan-' if and when the tank corrodes or otherwise
dei~- -,orates.
Capping all fill lines, p-oduct lines, vent lines, etc., to prevent
future entry into the tan- .
wore detailed ir'orTation on on-site closure of underoround tar'-s is
available in N^PA 30(1) and AH Publication 1604 (?).
f. Removal of Tank System
Practices *~>r remove1 cf tan', s TJSt include procedures for:
Removing all liquid product.
Disconnecting and capping all plumbing and controls.
Temporarily plugging all tank openings except for a 1/R-inch hole for
ventina.
Removing the tank fror the ground.
Freeing the tank of all flammable or toxic vapors.
Transporting the tank from the site.
If the tc~- is to be disposed of, -a sufficient number of holes should he
made in it to render it unfit for further use. The reason for making holes in
the tank is to discourage possible future use of it as a container for
products that would be contaminated by residual deposits of the material that
was previously stored in the tank. Sources of more information on the
disposal of storage tanks include NFPA 30 (1) and API Publication 1604 (2).
Removed fiberglass reinforced plastic (FRP) tanks may sometimes be reused,
providing a thorough inspection of the tank has been made by a factory
approved agent of the tank manufacturer and the manufacturer has certified the
tank as acceDts'rle for reuse.
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13-13
13.1.4.1 Guidance Soil Samplinq and Removal Procedures
The guidance suggestions outlined in Section 13.1.2.1 detail the
regulatory guidelines for the determination of soil contamination. Tan'-.
stnr?cc systems without the full secondary containment components aenerallv
folio* these requirements:
° Increase the number of soil tests to assure that the tank(s) did not
leak and thereby contaminate the surrounding soils.
0 Additional test parameters to indicate whether the tank contents
contaminated the surrounding soils.
0 Greater volume of soil removal because of excess surface hazardous
vaste sniilaae o*" lea'-.ina tar>/pipina systems.
13.1.^ Regulatory Citation
A .description on cost estimates for closure and post-closure care must he
included with the Part B permit application, as specified in:
"$26'.1*2, Cost estimate for facility closure,"
"$264.144, Cost estimate for post-closure monitorina and maintenance."
13.1.5.1 Guidance
All facilities that store or handle hazardous wastes are required to
prepare closure, if applicable, and post-closure plan cost estimates.
a. Closure Cost Estimate
0 Owner or operator must prepare closure cost estimate in current
doll 3--S.
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13-
0 Yearly updates of the closure cost estimate are required to account
for inflation, as described in 40 CFR 246.14?.
The owner or operator of the facility must prepare a closure cost estimate
in current dollars, reflecting the cost of closure at the point in the
facility's ope^atinc life when closure would be the most expensive, ^
indicated by the closure plan. The closure cost estimate must reflect all
costs which will be associated with the closure of the tank system. The
"worst-case," or maximum cost closure cost estimate should be prepared
reflecting maximum anticipated costs for each planned closure activity. All
closure activities identified in the closure plan should be covered in a
closure cost-estimate, including:
c Cost ~f manpower for performing closure activities;
Co?! c~ "e^'tec eojip^ent o>" subcontractors' costs f(x tcr- re~~.'^~,
soil excavation, decontamination of equipment and/or tanks and other
closure activities;
0 Cost of analytical work to determine the extent of soil
contamination, if any;
0 Costs associated with transport and disposal of contaminated tankaae,
pipina, appurtenances anc soil;
0 Cost of obtaining an independent professional engineer to certify the
closure activities;
0 Contingency and administrative costs; and
0 Any other associated costs.
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13-15
Closure cost estimates should be prepared in a tabular form, clearly
reflecting all closure activities and their relative costs. An example of a
closure cost estimate for a tank system can be found in Table 13-1.
b. Post-Closure Cost Estir-ate
If any hazardous wastes, contaminated soil or contaminated tank systems
remain on-site followina the closure activities, the operator is required to
develop a post-closure plan and cost estimate for the plan.
Items in a post-closure cost estimate which should be reflected by their
relative projected annual costs may include the followina:
0 Inspection and security costs;
0 Maintenance costs for the site:
c Monito-'ina and analytical costs;
0 Any other costs relatina to the post-closure care activities.
The post-closure cost estimate should be presented in tabular form,
clearly indicating each post-closure activity and its relative costs. The
post-closure cost estimate must be updated whenever a chance in the
postclosure care plan increases the cost of the post-closure care as reauired
under
Owner or operators must maintain post-closure monitorina ana
maintenance if all contaminated soils, residues or structures are not
removed from the site. The owner/operator is required to prepare, in
current dollars, annual post-closure cost estimates for the
continuing operations of monitoring and facil ity maintenance.
During pre-closure operations, post-closure cost estimates must be
updated yearly to account for inflation.
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13-16
TABLE 13-1
EXAMPLE CLOSURE COST ESTIMATE
Closure Cost Estimate for the Removal of Three Underground Storage Tanks
and Associateo ripino, Valves and Appurtenances.
1. Removal of Tank Residue $ 1,350
SI udqe Removal /Transport/Dispos al
(10-55 qallon drums f? $135.drum)
2. Tank RemovaVTransport/Disposa"
A. Tank Excavation (Subcontractor Cost) . 2,200
($1,100/day
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13-17
0 The post-closure cost estimate must be revised durino the facilities
operation to account for any chanqes in operations or additional cost
increases.
0 The updated versions of the closure and post-closure cost estimates
must be keot at-the facility durina its operating life.
13.2 K'a jor Issue Points
1. Have the removal and/or abandonment procedures been clearly
i denti fied?
2. Has the fate of the removed or decontaminated tank system been
i denti f ied?
Does tie clo^j-'t p ^ crr-'ess cc^lete removal of the tari'-, systerr and
contaminated soils in a logical manner? If the tank is to remain in
place, have the closure activities been clearly identified in the
closure plan?
d. If no hazardous wastes or contaminated soils are to remain at the
site followino closure, has an appropriate closure cost estimate been
prepared which clearly reflects all closure costs?
5. If the tank is to remain in place, has further use of or access to
the tank been adequately prevented?
6. If contaminated tankage, soils or other residues is to remain on-site
following final closure activities, has an appropriate post-closure
plan and cost estimate been prepared?
7. If a temporarily closed tank system is to be re-activated for use,
has it been sufficiently determined that the tank is fitfor-use, and
are the ne* materials to be stored in that tank compatible with the
previously stored contents?
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14-1
14.0 PROCEDURES FOR TANK SYSTEMS THAT STORE OR TREAT IGNITARLE, REACTIVE,
OR INCOMPATIBLE WASTES
1^.1 Regulatory Citations
I nf orma tic-n on tan'.- svster r^sian ,". r 'p°ret1'ic proceed PS fn«- a tar-
syste1 that steles o" treats io^it^lp, -eactivp, or incompatible wastes must
be included in Part B of the RC^A permit application, as specified in Se
27n.ifi(k):
"For tank systems in which ianitable, reactive, or imconpatible
wastes are to he sto"e^ or treated, a description o^ ho^
operating procedures and tank system and facility desion will
achiex'e compliance with the reauirements of
265.199."
the risks fron- storaae or treatment of these special types of wastes. Such
risks include fire, qas and/or hea': generation, explosion, etc.
1 a.i .1 Citation: lom'tahle or Reactive Wastes, General Precautions
Section ?6^.19P states the special recuirenents for iqnitable or reactive
wastes. These wastes cannot be placed in a tank or its ancillary e'uip^eit
unless:
"{!) The waste is treated, rendered, or mixed before or immediately
after placement in the tank system so that the resulting waste,
mixture, or dissolved material no longer meets the definition of
iqnitable or reactive waste under §261.21 or 261.23 of this
Chapter, and 6264.17(b) is complied with; or
(2) The waste is stored or treated in such a way that it is pro-
tected from any material or conditions that may cause the waste
to ignite or react; or *
(3) The tank system is used solely for emergencies."
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14.1.1.1 Guidance to Achieve the Part 264 Standard
A major factor in the proper handlino of hazardous wastes is a waste's
iqnitability and reactivity characteristics, as described in:
"$261.21, characteristic of iqnitability;
"SP61.23, char acte^istic of reactivity;
"£264.17, qeneral reauireme"ts for ianitable, reactive, or incom-
patible wastes.
When a facility stores, treats, or disposes of ignitable or reactive
wastes, precautions must bc ta'-en in order to avoid one or more of the follow-
inq undesirable and danoe^ous reaction consequences:
2. Fire produced from extremely exothermic reactions, iqnition of
reaction mixtures or o* the reaction products.
3. Innocuous gas qeneration (e.q., 063, f^) that can cause
pressur izat ion and subseouent rupture of a closed tank.
d. Toxic qas qeneration (e.a., ^pS, HCN).
5. Flammable qas qeneration (e.q.,
6. Explosion resultinc fro~ a viac^ous reaction or a reaction
producino sufficient heat to detonate an unstable reactar.t or
reaction product .
7. Uncontrolled polymerization producinq extreme heat and possibly
flammable and toxic qases.
8. Solubil ization of toxic substances (including metals).
Dissipation of hazard can be achieved by ensuring that any ignitable or
reactive waste will not be placed in a storage tank unless the waste is
treated, mixed, or rendered inert prior to or immediately after placement in
the tank. The process selected to alter the ignitable or reactive character-
istic(s) of a waste must be waste-specific. For example, an ianitable
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14-3
material might be mixed with water to raise its flash point, but only if the
material is miscible with water and is not water reactive. Extractino reac-
tive constituents from solution miaht be an acceptable way of makina a waste
non-reactive. The specific process used to alter the iqnitable or reactive
characteristics of a waste mjst be tested and validated at bench scale be'o-e
it is applied at an industr-iel tank facility. Most importantly, if a waste is
mixed with another materia1 (waste cr otherwise), the mixed materials must not
be incompatible.
The resultinq waste material, followino treatment or mixing, should no
longer fit the definition of iqnitable or reactive waste, as specified in
Sections 261.21 or 261.23, respectively (see Figure 14-1). The waste must
also comply with all requirements of Sections 26^.17 (see Fiqure 14-2).
Sections 26^.17(a) and 26^.17(b) are eauivaTent, in essence, to Section
~; i ~C.-t* ' ^^ - - - - '. f~[. 'Cr'i ;' . -,;. ^-. »i- ;> nr -."£ ;t ~\ c r~ rS i'"- ~ ^^
instituted to ensure that any storaqe and treatment methods do not cause the
waste to ignite or react. For example, a tank system should he isolated from
potential sources of sparks, flames, lightnina, smokinq, etc. This requlatory
section enables a RCPA incineration facility to store ignitable wastes if and
only if the facility is designed and operated ir a manner that the stored
wastes will have no possibility for icrition. Static sparks, from liauid
movement in a tank causina an accumulation of static charge, can he prevented
'by avoiding "sp1 ash-'f ^ 1-i inc" a tank, limitino the velocity o* an inco^inc
v.aste strec" "
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14-4
Figure 14-1
40 CFR 261.21
Characteristic of Ignitability
(a) A solid wast* exhibits the charac-
teristic of ignitabillty If a representa-
tive cample of the waste has any of
the following properties
(1) It l£ a liquid, other than an aque-
ous aolutlon containing less than 24
percent aJcohol by volume and has
flash point less than 60'C (140'F), as
determined by a Pensky-Martens
Closed Cup Tester, using the test
method specified In ASTW Standard
D-93-78 or D-93-*0 (incorporated by
reference, see f 260.11), or a SeLaflash
Closed Cup Tester, using the test
me:r.:>i specific; lr. ASTM EiandbJO
D-3276-7B (Incorporated b> reference,
we 1960.11), or as determined by an
equivalent test method approved by
the Administrator under procedures
ael forth In |i 260.20 and 260.21.
(2) It is not a liquid and is capable,
under standard temperature and pres
surt, of causing fire through friction.
absorption of moisture or spontaneous
chemical chances and. when Ignited,
burns ao rigorously and persistently
that is creates a hazard.
(3) It Is an ignltable compressed (as
as defined In 49 CFR 173.300 and as
determined by the test methods de
acrtbed In that regulation or equiva-
lent test methods approved by the Ad-
ministrator under || 260.20 and 260.21.
<4> It 15 an oxidizer as defined ir. 49
CFR 173.151.
(b) A solid waste that exhibits the
characteristic of ignitabillty. but is not
listed as a hazardous waste in Subpart
D. has the EPA Hazardous Waste
Number of D001.
40 CFR 261.23
Characteristic of Reactivity
(a) A solid waste exhibits the charac-
teristic of reactivity if a representative
ample of the waste has any of the fol-
lowing properties-
(1) It Is normally unstable and readi-
ly undergoes violent change without
detonating.
(2) It reacts violently with water.
(3) It forms potentially explosive
mixtures with water
(4) When mixed with water, it gener-
ates toxic gases, vapors or fumes in a
quantity sufficient to present a danger
to human health or the environment
(5) It is a cyanide or sulfide bearing
waste which, when exposed to pH con-
ditions between 2 and 12.5, can gener-
ate toxic gases vapors or fumes in a
qua!ttit> suffiner.1. tc present a d&r.Efr
to human health or the environment
(6) It is capable of detonation or ex-
plosive reaction if it is subjected to a
strong Initiating source or if heated
under confinement.
(7) It Is readily capable of detona-
tion or explosive decomposition or re-
action at standard temperature and
pressure.
() It is a forbidden explosive as de
fined In 49 CFR 173.51. or a Class A
explosive as defined In 49 CFR 173.53
or a Class B explosive as defined in 49
CFR 173.88
A solid waste that exhibits the
characteristic of reactivity, but is not
listed as a hazardous waste in Subpan
D, has the EPA Hazardous Wast*
Number of DOG3
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14-5
Figure 14-2
40 CFR 264.17
General Requirements for Igmtable, Reactive, or Incompatible Wastes
(a) The owner or operator must take
precautions to prevent accidental ignl-
lion or reaction of ignitable or reactive
waste. This waste must be separated
and protected from sources of ignition
or reaction Including but not limited
to: open names, smoking, cutting and
welding, hot surfaces, frictional heat.
sparks (static, electrical, or mechani-
cal), spontaneous ignition (e.g . from
heat-producing chemical reaction;; >,
and radiant heat While Ignltable or
reactive waste is being handled the
owner or operator must confine smck-
lr? a^d OTT flBr to sprria!^ dc~ f
natea locations "No SmoKinp sipns
must be conspicuously placed wherev-
er there Is a hazard from Ignitable or
reactive waste.
(b) Where specifically required by-
other Sections of this Part, the owner
or operator of a facility that treats.
stores or disposes Jgnitable or reactive
waste, or mixes Incompatible waste or
Incompatible wastes and other materi-
als, musi take precautions to prevent
reaetons which
(1) Generate extreme heat or pres
sure, fire or explosions, or violent reac
tions:
(2) Produce uncontrolled toxic mists.
fumes, dusts, or gases in sufficient
quantities to threaten human health
or the environment;
(3) Produce uncontrolled flammable
fumes or rases in sufficient quantities
to pose a risk of fire, or explosions.
(4) Damage the structural Integrity
of the device or facility;
(6) Through other like means
threaten human health or the envi-
ronment
-------
14-6
Table 14-1
Iqnition Prevention References
Document Numbe" "^tie Date
API RC 2003 Protection Aaainst lanitions Arisina 19R2
Out of Static, Liohtnina and Stray
Cu'"1*erts, Fourth Edition
NFPA 30 Flammable Moulds Code 1984
NFPA 70 National Electrical Code 1984
NFPA 77 Pecommended Practice on Static Electricity 1983
NFPA 78 Lig^tnina Protection Code 1983
NFPA SPP-1E Fire Protection Guide on Hazardous 1984
-------
14-7
A tank system may contain iqnHable or reactive waste in an emergency
situation, in accordance with Section 264.198(a) ( 3). For instance, if there
is a fire in one portion of a facility, ignitable wastes may have to be moved
temporarily to other tanks at the facility during this emeraencv. The
temporary storaae tanks may not be as well protected from lightmna, for
example, as the tanks nea>- the fire, but under the circumstances, the
temporary storaoe tanks are still mo^e protective of the wastes than havina
the wastes remain near- the fire. Similarly, if a malfunctioning pump cannot
be shut off, ignitable wastes may be placed in other tanks temporarily, until
the pumpina problem is resolved and the wastes can be removed to the proper
tanks. An own e»V opera tor does not want to make an emergency situation worse,
however, by placing ignitable or reactive wastes temporarily in tank systems
where there is a high probability of ignition or reaction.
a r> r a
Protective distance reauirements for the storaae of ignitable or reactive
wastes are specified in Section 26^,198(b). This section states:
"The owne" o>- ooerator of a facility where ignitable or reactive
waste is stored or treated in a tank system must comply with the
reauirements for the maintenance of protective distances between
the waste management area and any public ways, streets, alleys,
or an adjoining property line that can be built upon as reouired
ir 'e^es 2-1 throuoh ?-6 of the National Fire Protection
Association's "Fi a~nable and Combustible Liauid? Code" (1977 or
19rn '.'
14.1.2.1 Guidance to Achieve the Part 26d Standard
In order to store or treat ignitable or reactive waste, the owner or oper-
ator of a facility must comply with protective distance requirements for
tanks, as specified in the National Fire Protection Association's "Flammable
and Combustible Liquids Code" (NFPA 30). The principal tank siting criteria
are based on the distance between tanks and the spacing between a tank and a
property line and/or nearby structjres. Restrictions on spacing are gene-ally
based upon a fra:tion of a tank's diameter.
-------
14-8
NFPA classifications for tank contents are defined in Figure 14-3. These
definitions must be applied when using NFPA 30 tank siting criteria tables
(Tables 14-1 through 14-6). The NFPA definitions have to be compared to the
40 CR 261.21 and 261.23 (Figure 14-1) definitions of ignitables and
reactives. For example, a liauid waste with a flash point of 95°F (?E°C) is
classified as an ignitable under the RCRA regulations and is a flammable, not
a combustible, liquid by the NFPA.
Types of tanks, protective measures, and minimum distance require- ments
for stable liquids with operating pressures of 2.5 psig (17.24 kPa) or less
and greater than 2.5 psig are specified in Tables 14-2 and 14-3,
respectively. NFPA protective distance retirements for boil-over liquids and
unstable liquids are listed in Tables 14-4 and 14-5, respectively. Tables
14-6 a^d U-7 deterrr.ine spacing by tank capacity. Table 14-6 refers to Class
11 IK Mqu'iGi, wine1. &' e co~" wSt'i: le liases *it'-i f'^esh point; ct z-~ &': 5ve
200°F (93.4°C). Table 14-7 is a reference table for use with Tables 14-2
through 14-5.
14.1.3 Citation: Incompatible Wastes
Section 26^.199 contains the special requirements for handling potentially
incompatible wastes. These requirements apply all precautionary measures to
'the entire tan- syste~. The measures are:
"(a) Incompatible wastes, or incompatible wastes and materials, rust
not be placed in the same tank system, unless §264.17(b) is
compl ied with.
(b) Hazardous waste must not be placed in an unwashed tank that
previously held an incompatible waste or material, unless
§264.17(b) is complied with."
The requirements of Section 264.17(b) (see Figure 14-2) are that precau-
tionary measures be instituted to ensure that all incompatible, reactive, or
ignitable wastes treated, stored, or disposed of at a facility do not react to
produce a hazardous reaction consequence (i.e., explosion, toxic gas genera-
tion, violent polymerization, etc.). Waste compatibility characteristics must
-------
Figure 14-3
NFPA 30 Classifications for Tank Contents
Boil-Over. An event in the bumina of certain oils in an open top tank
^, after a lonq period of Quiescent bumina, the^e is a sudden increase - , + r^c , 1«". /&- ,^t-'' "'c 0'--:e'i C"" P""tfS ? t?";
containina not viscous oil. Uoon mixina, the sudden conversion of water
to steam causes a portion of the tank contents to overflow.
Boiling Point. The temperature at which a liquid exerts a vapor
pressure of 1^.7 psia (760 mm Hg). Where an accurate boilinq point is
unavailable for the material in question, or for mixtures which do not have a
constant boiling point, for purposes of this code the 10 percent point of a
distillation pe-formed in accordance with ASTV D-8F-82. Standard Method o*
Test for Distillation of Petroleum Products, m;y be used as the boilina point
of the 1iquid.
Combustible Liquid. A l->auid hgvina a flash point at or above lnO°F
Combustible Liquids shall be subdivided as follows:
Class II liquids shall include those having flash points at or above
100°F (37.8°C) and below 14Q°F (60°C).
Class IIIA liquids shal1 include those having flash points at or
above 140°F (60°C) and below 200°F (93°C).
Class III3 1 iouids shall include those having flash points at or
above 200°F (93°C).
-------
Figure 14-3 (continued)
NFPA 30 Classifications for Tank Contents
Flammable Liquid. A "Hot/id having a flash point below 100°F (37.s°O
a^d havina a vapor pressure not exeedino 40 Ibs per so in. (absolute) (?,0f-
mT Ha) at 'TOO0' (37.8°C) shall be know as a Class I liouid.
Class I liquids shall be subdivided as follows:
Class IA shall include those havinq flash points below 73°F (22.8°C)
and havina a boilina point below 100°F (37.8°C).
Class IB shall include those havino flash points below 73°F (22.8°C)
and havinq a boilinq point at or above 100°F (37.8°C).
Class 1C shall include those havinq flash points at or above 73°F
(22.8°C) and below 100°F (37.8°C).
Flash Point. The Finim^ tenpe-ature at which a liauid qives off van1-"-
r £ t . /- 4 ~~ * /-n^'-or-*»-3*''n'~ * ~ f r*-~ an ^pf->'*'i'~1c "- ! y + < j y c. v^t^ s i >' n e s ^ V ?
surface of fie liquid within the vessel as specified by appropriate test
procedure and apparatus as follows:
The flash point of a liquid havina a viscosity less than 45 SUS at 100°F
(37.8°C) and a flash point below 200°F (93°C) shall be determined in
accordance with AS TV D-56-82, Standard Method of Test for Flash Point by the
Taq Closed Teste>-.
The flash point of a liquid having a viscosity of 45 SUS or more at
(93°C) or hiaher shall be determined in accordance with ASTV D-93-8n, Standa-c!
Method of Test for Flash Point by the Pensky Martens Closed Tester.
As an aUe-nate, ASTV- D-3828-81, Standard Methods of Tests for Flash Point
of Pet'o'ej" a I'd Petr-oiejr- Products by Setaflash Closed Tester, rrsy he useo
for testing aviation turbine fuels within the scope of this procedu-e.
As an alternate, ASTM D-3278-82, Standard Method of Tests for Flash Point
of Liquids by Setaflash Closed Tester, may be used for paints, enamels,
lacquers, varnishes and related products and their components having flash
points between 32°F (0°C) and 230°F (H00C), and havinq a viscosity lower than
150 stokes at 77°F (25°C).
As an alternate, ASTM D-3828-79, Standard Test Methods for Flash Point of
Liquids by Setaflash Closed Tester, may be used for materials other than those
for which specific Setaflash Methods exist (cf., ASTM D-3243-77 for aviation
turbine fuels and AST** D-3278-78 for paints, enamels, lacquers, varnishes,
Delated prodo:ts and their components.)
-------
u-n
Figure 14-3 (continued)
NFP/s 30 Cl assifications for Tank Contents
Liquid. For the purpose of this code, any material which has a fluidity
greater thai that of 30^ penetration asphalt when test°r' in accordance with
ASTK D-5-78, Test for Penetration for Bituminous Materials. When not
otherwise identified, the term liquid shall mean both flammable and
combustible liquids.
Unstable (Reactive) Liquid. A liquid which in
commercially produced or transported will vigorously
condense, or will become self-reactive under conditions
temperature.
the pure state or as
polymerize, decompose,
of shock, pressure, o^
-------
Table 14-2
Stable Liauids - Operating Pressure 2.5 psiq or Less
Type of Tank
Protection
Minimum Dutance in Feet from
Property Line Which It or Can
Be Built L'poo. Including the
Oppo.it* Side of i Public WIT
and ShaU Be Not Lm Than 5 Feet
Minimum Distance in Feet from
Ne»rcM Side of Any Public WIT
or from Nearot Important
Building oa the Same Property
and Shall Be Not Lea Than 5 Feet
Protection for Exposures*
timei diameter of tank
timo diameter of tank
Floating Roof [See 22 1 l(a)j
None
Diameter of tank but need not
exceed 175 feet
timet diameter of tank
Vertical «iih Weak Roof to
Shell Seam (See 2 2 5 5)
Approved foam or merting
syvem' on tarju not exceed
ing 150 feel in diameter""
V, timn diameter of tank
timet diameter of tank
Protection for Exposure*'
Diameter of tank
14 timei diameter of tank
None
2 timn diameter of tank but need
not etceed S50 feet
X timet diameter of tank
Horizontal and Vertical with
Emergency Relief Venting to
Limn Pmuret to 2.5 ptig
Approved merting lyjtem"
on the tank or approved
foam svstrm on vertical l
S tim« Table 14- 6
S timei Table 14-6
for
Table 14-6
Table 14-6
Nonf
i '.T-.fs Table 14-6
Table 14-6
* See definition for 'Protection for Exposures
See NFPA 69, Exploncm Prevention S>j«rru
* For tankj over 150 ft in diameter use Protection for Exposures or None ai applicable
SI Umu 1 ft 0 SO m
Protection for Exposure* Fire protrction for struc
tures on propfrt) adjacent to liquid storagr Fire protfc
tion for such structures thai! bt acceptable when located
(1) within the jurisdiction of any public fire department
ot (2) mdjacem to plants having private fire brigades
capable of providing cooling water ttreams on structures
on propert) adjacent to liquid storage
Source: Table 2-1,
-------
Table 14-3
Stable Liquids - Operating Pressure Greater than 2.5 psia
Type of Tank
Pnxecuon
Minimum DUUDCC in Feet fiom
Property Line Which It or On
Be Built Upon, Including the
Oppoine Side of » Fublic W»y
Minimum Duupce io Feet from
Nearest Side of An» Public Wav
or from Nearat Imporunt
Building OP the Sime Propem
Protection for Enpoiurei*
Any Type
IS times Table 14-b but thai! not
be Iru than 2!> feet
lima Table 14 6bui thili not
br Im than 25 fret
None
3 tim« Tablf14 6but shall riot
be leu than 50 feet
I'/, timet Tablel4-6but shall not
be leu than 2S feet
Ser definition for Protection for Exposure) '
SI Umu 1 ft - 0 SO m
Protection for Exposures. Fire protection for strut
tures on propem adjacent to liquid storage Fire protec
lion for such structures shall bf acceptablf when located
(1) uithin ih' jurisdiction of am public fire departmrrr
0; ("; adjzccr,' u p!ani- ha\,r,^ pn\att fi:-» bngad'-
Capable of providing cooling water streams on structures.
on propert) adjacent to liquid storage
CP:
-------
14-14
Table 14-4
Boil-over Liquids
Type of Tank
Protection
Minimum Duuocr in Feei from
Propem Line Which li or Can
Be Built Upon, Including the
Opposite Side of a Public Wa>
ind SbaU B< Not Le» Thin 5 Feet
Minimum Distance IE Feei frotr
Tsearat Sidt of An» Public M t\
or {root Nurai Important
Building on the Same Propen>
ind Shall B< Not LIB Than 5 Feet
Floating Roof [S« t 2 1
Proiccuon lor Ejipoturrs*
i umn diamnrr of tank
umn diimnrr of tank
Nonr
Diameter of lank
dumfifT of tank
Approved foam or menmg
lYJtrrr"
Diametct of tank
times diameter of tank
Fixed Roof [Sec 2 2 1
Protection for txposures'
J timn diameter of tank
timn diameter of tank
Nonr
4 umn diameter of tank but need
not exceed 550 feei
timn diameter of tank
See definition for "Protection for Liposurrs
| ** See NFPA 6? Lfphnon Frevmtion
SI Umtj 1 fi = 0 SO m
Protection for Exposure*. Firr proTfrtion for struc
turci on proprnv adjacent to liquid storag' Fir<
tior, fo; »u:K s;run-rf. it-.*;, L" accrp.alr vfirr.
(1) within thr junsdiction of am public fire d
or (2) adjacent 10 plants having private firt brigades
capable of providing cooling water streams on structures
on proprrt) adjacent to liquid storage
-------
Typr of 7 ink
Horitonul «nd Vrruca)
Tanks «ith Imrrgtno Rrlirl
Vtncmg 10 ftrtnit Pre*»urr
Noi in txcru of 2.5 ptig
Protection
1 anl. pT oirc irri v> n h
onr of ihr folln* mi
Approsrd inrnmf; '
Approvrd insulaunn and
Tfl'tlgrliUO^ Apprcnf^
bamcadt
Pioirrnorr for Expnsurr^**
-IS
Table 14-5
Unstable Liquids
Minimum Pistamr in frt( (torn Minimum Dmarur ir, Irri (rurr
Propcm Linr VhirK J« or C»n NtaTr»i Side of An> Publir V i\
Br Buih Vpon. Including ihf or from Nrarrv Imponam
OppoMir Side of I Public >*i\ Building on thr Same Proprru
ablr146bji noi )rsi ihan
Zb frn
'T timri 7»blr14-6but noi less
than 50 frri
x T ablt14-6but not
ihan )0t frf.
Honrontal and \rrntj'
ark> »,:h Lrrtrp'ic* !>'"
\cnting 10 Ptrrnn Prevurt
O>cr 2.5 p»ig
lank proircird *uh an\
onr 0^ thr following
ApprovrG v.a\ri sprai.
Aprroifd inrmne *
A f'; ' > vr ;A i n ^ j' ^ i a r -
2 timrx 1 ablrt4 6bui not
tha-, bC frri
Protrction foi Expo^urrs"
umri 1 abli14-6bui not
than 100 frn
Non'1
6 timrs Tablf14-6bui noi
ihan IbO frn
* Srr NFPA 69 £xp/03i3". Prficn.'ion
Sfr drfmnion for Protfnior, for i
SI Units ] ft = 0 SC n-
Protection (or Exposure*. Fiff protection for Urur
tures on property adjacent to hquid storagf Firt protec
lion for luch structures shall b* acceptablf when located
(I) within thr jurisdiction of am public fire department,
01 (2) adjacent to plant' ha\mg private fire brigades
capable of prodding cooling vatet streams on structures
on proptrt) adjacer,: to liquid iioiagt
Noi lr>- than S; Irri
Noi Ifis than SO
Noi )r^ than 100 frr
Noi Iris tha* bf1 frr
Noi Iris than IOC frri
Not Iris than ISO (rrt
Sou-c*?:
-------
14-16
Table U-6
Class IIIB Liauids
C«p»clt> G«llon»
Minimum Distance In
Ft*t from Prop*rt> Lint
Ithlch li or Can B« Built
Upon. Including th«
Opposite Sldt of Public
Minimum Duttnet In
Fttt from Nttrttt Sldt of
An\ Public ^»> or from
K°
12,000 or loi
12,001 to 30,000
30,001 to $0,000
50,001 to 100,000
100,001 or more
5
10
10
15
15
5
5
10
10
15
SI I mis 1 ft = 0 504? m
= 3 ~t'~> L
Sc^ce:
-------
k «^
U-17
Table 14-7
Reference Table for Use in Tables 14-1 through 14-4
apacli) Tank
Gallon*
Minimum DUtanc* In Minimum Dtitanct ID
Fert from Proptrtx Line Fret from Nearest Sldr of
Which U or Can Br Built
Upon. Including thr
Oppotltr Sldr of a Public
Public >*a> or from
Scarirtt Important
Building on tht Same
Prop*rt>
275 or lew
2?6 to 750
751 to 12,000
12,001 to 30,000
30,001 to 50,000
50,001 to 100,000
100,001 to 500,000
500,001 to 1,000,000
l.Ovj.OOl tc 2,001,000
Z.CvO,01'! to 2,0.',',OJc
3,000,001 or more
5
10
15
20
30
50
80
100
135
163
175
5
5
5
5
10
15
25
35
45
5S
60
Source: TaMe ?-
-------
14-1R
be determined for these reactions to be avoided. If a waste is to be
stored in an unwashed tank that contained a chemical with which the waste
is considered incompatible, appropriate decontamination procedures must
be performed to avoid a hazardous reaction conseauence.
14.1.3.1 Guidance to Achieve the Part 263 Standard
Specific precautionary measures must be followed in the handling
and/or storage of potentially incompatible hazardous wastes in order to
prevent or reduce the chances of an adverse reaction. Combining or
mixing of incompatible hazardous wastes can produce reactions or reaction
products that have the potential to harm public health, welfare, or the
environment. These hazardous reaction consequences have been compiled
into eiaht classes, listed in Section 14.1.1.1.
Wastes are not necessarily incompatible whenever they react with each
other. Reactions involving neutralization or dissolution of one
substance by another, such as metals dissolved by acid, are generally not
considered to be incompatible. If, however, such reactions result in
fires or explosions or they generate toxic substances in amounts
sufficient to endanaer public health, safety, and the environment, they
are regarded as incompatible.
If conclusive information is not available on the compatibility of
tvvo wastes, a controlled trial mixing of the wastes in small amounts can
be used to determine potential consequences. In general, the following
steps should be used at a facility to determine waste compatibility:
1. Request from the generator as much information as possible about
a waste, since the information required on a waste manifest is
very general and of little use in determining compatibility.
2. If a waste has not been handled previously at a facility,
analyze a representative sample of the waste. The information
obtained throuah waste analysis should substantiate the
generator's information and determine if additional information
T ^ r. oo Ho H
-------
3. Use the information on waste conmposition gathered in a first
and second steps in conjunction with other available information
on chemical constituents to determine waste compatibility. If
the information is not conclusive, potential consequences of
mixing the wastes should be determined throuqh trial tests.
The quantity of a sample to be jsed for trial mixina depends on individual
circumstances. Samples should be of sufficient size to produce clearly
discernible effects of the mixinc. The samples must, however, be sufficiently
small to assure that any reaction can be controlled.
One can determine the extent of upper and lower explosive limits for
flammable pases by carefully observing upward flame propagation throuqh a
cylindrical tube. The amounts of toxic gases produced as a result of a
reaction may be discovered by aas chromatoqraphy for organics and by specific
10*1 electrode? for ma^v inc^canic oases in solution,
One method for quickly detecting the evolution of toxic gases involves the
use of detector tubes, a variety of which are commercially available. To
determine if toxic gases a»"e produced by the reaction being tested, the qas is
f
aspirated throuqh a detector tube for the specific gas.. A change of color in
the tube indicates the presence of a particular aas, the concentration of
which is proportional to the lenath of the chanqed color in the tube. A
sinqle tube can detect the presence of more than 2n qases.
The mix ire of two wastes for which oily limited information is available,
however, can result in hiqhly violent and dangerous reactions. Safety
precautions must therefore be taken to protect laboratory personnel. The
precautions include wearinq explosion-proof hoods and safety glasses and the
surroundings should be fire resistant. Safety showers, eye-wash stations, and
first-aid kits should be available. All personnel should be familiar with
fire and emergency procedures.
-------
14-20
The reactions between two wastes in a small-scale test may not accurately
reflect the results of large-scale mixing. In large-scale operations,
reactions that appeared insignificant or were undetectable in the laboratory
can have significant consequences (such as generation of large amounts of heat
or toxic fumes). It is'obvious, therefore, that extreme care and adequate
safety precautions should always be used when mixing or treating large
quantities of hazardous waste.
In addition to laboratory testing of compatibility, an analytical method
has been developed to determine waste compatibility. This method utilizes a
binary combination of chemical classes to predict the likely reaction
consequence of combining chemicals from two different classes at standard
temperature and pressure. EPA's Municipal Environmental Research Laboratory
publication, "Desian and Development of a Hazardous Waste Reactivity Testing
Protocol" (N~IS number PEc-^15f?37, 19&4) details laboratory procedures to
classify an unknown waste into a reactivity class.
Cla-sses of chemical compounds are listed in Table 14-8. Compounds are
classified according to similar molecular structure (classes 1-31) and similar
reactivity characteristics (classes 32-38). In Table 14-9, a representative
list of chemicals for each class is provided. If further chemical identifi-
cation is necessary, it may be obtained from the following sources:
0 Dangerous Properties o* Industrial Materials, Sixth Edition
(Sax, 1984);
° The Merck Index, Tenth Edition (Merck, 1983);
° A Method for Determining the Compatibility of Hazardous Wastes
(Hatayama et al., 1980); EPA-600/Z-80-076, April 1980, US EPA
Office of Research and Development (soon to be released by ASTM
as a standard);
0 Guide and Procedures Manual (MD489/D335), Toxic Substance
Storage Tank ContainmentAssurance and Safety Program, State of
Maryland, Department of Health and Mental Hygiene, Office of
Environmental Programs, Baltimore, MD, September 1983;
-------
Table 14-S
List of Chemical Classes
Chemical Class Ni^ber Class Name
1 Acids, mineral, non-oxidizing
2 Acids, mineral, oxidizing
3 Acide, organic
4 Alcohols and glycols
J Aldehydes
6
7 Amines, aliphatic and aromatic
8 Azo compounds, diazo compounds, and
hydrazines
9 Cerbamates
10 Caustics
11 Cyanides
12 Dithiocarbaretes
13 Esters
15 Fluorides, inorganic
16 Hydrocarbons, aromatic
17 Helogenated organice
1B Isocyanates
19 Ketones
20 ^rcaptans and other organic aulfides
21 Metal corrpounds, inorganic
22 Kitrides
23 Nitrites
24 Nitro compounds
25 Hydrocarbons, aliphatic, irisaturated
26 Hydrocarbons, aliphatic, aeturated
27 Peroxides and hydroperoxides, organic
2E Phenole and cresols
29 Organophosphetea, phoisphothioates ,
and phoaphodithioates
30 Sulfides, inorganic
31 tpoxides
32 Combustible and flarmable materials
33 Explosives
34 Polymer liable compound a
35 (Vidizing agents, strong
36 Reducing agents, strong i
37 Nster and mixtures containing water
3B Water reactive aubstancea
Source: Hatayema, et^ aj. , 19BC.
-------
14-22
Table 14-9
List of Chemical Representatives by Class
f
Class 1 At: ids, Mineral, Npn-Q»id izing
Boric Acid
CMorosulfonic Acid
Hydriodic Acid
Hydrobrcr'ic Acid
Hydrochloric Acid
Hydrocyanic Acid
Hydrofluoric Acid
Hydroidic Acid
Phosphoric Acid
Claes 2 Acids, Mineral Oxidizing
Chloric Acid
Chroric Ac id
Nitric Acid
Clear
PercMorir Arid
Sulfuric AciC
Sulfur Trioxide
Class 3 AcidSj Organic (All lecxrere)
Acetic Acid
Benzoic Acid
Formic Acid
Lactic Acid
Meleic Acid
Cleic acid
Salycilic Acid
Phthalic Acid
Class 4 Alcohols and Clycole (All
Isomers;
Allyl Alcohc]
Chloroethanol
Cyclohexanol
£th»r»l
Ethylene Chlorohydrin
Ethylene Glycol
Ethylene Clyocol Monomethyl Ether
Glycerin
Methanol
Monoethanol Awine
Class 5 Aldehydes (All lecners)
Acetaldehyde
Formaldehyde
Furfural
Class 6 AT ides (All Isomere)
Acet&Tiide
Clase 7 Amines, Aliphatic and
Aromalic (All laomera)
toinoethanol
Aniline
Diethylamine
Oiamine
Ethylene ndiairane
Hethylemine
Hanoethylanolamine
Pyridine
Class 6 Azo Compounds, Pi"*0 ^°
pounds, and Hydrazings
Hydrezine
Hydrazine
ClesB 10 Caustics
Ammonia
Ammonium Hydroxide
Hydroxide
Carbonate
Hydroxide
Sodium Hypochlorite
Class 11 Cyanides
Hydrocyanic Acid
Potaasiurr. Cyanide
Sodiun Cyanide
Group 13 Eatere (All Isomera)
Butyl Acetate
Ethyl Acetate
Methyl Acrylate
Methyl Formate
Dimethyl Phthalate
Propiolaetone
Class U Ethera (All Isomera)
Kchloroethyl Ether
Dioxane
Ethylene Glycol Honomethyl Ether
Oireth) If ormeride
Tetrahydrofuran
Class 15 Fluorides, Inorganic
Aluminum Fluoride
Ammonium Fluoride
Fluoroeilicic Acid
Fluosilic Acid
Hydrofluorosilicic Acid
-------
14-23
Table 14-9 (continued)
Cless 16 Hydrocarbons, Aromatic (All Isomers)
Benzene
Ethyl
Naphtha lene
Styrene
Toluene
Xy lene
Cless 17 Halngeneteci Organics (A)) Isomers)
Aldrm
8en/>l Chloride
Carbon Tetrachloride
Chloroacetone
Chlorobenzene
Chlorocresol
Chloroethenol
Chloroform
DicMoroacetone
Dichloroethylether
Dichloro"eth8ne (Meth> lene DicMoride)
Fthylene Dichloride
Treons
Pcntachlorophenol
let rschloroetharie
Trichloroethy lene
Class IE Isocyanetes (All
Cless 19 Kelones (All
Acetone
Acetophenone
Cyc lohe»enone
Dichlorcaretone
Diniethyl ketone
Meth> 1 tthvl >etone
Methyl Isobutyl Ketone
Qjinon* (Benzoquinone)
tlasi 20 Hercaptans and Other Orgiinic Sulfides
(All iBomers)
Carbon
Cthyl Mercaptan
Class 21 Metnl Compounds, Inorganic
Mum in iff Sulfate
Chrcnic Acid
Silver Kitrate
Tetraethyl Lead
Zinc Chloride
Class 25 Nitnles (All Isomers)
Ac" '""»- *
Class 2- Nil ro Prvpoun^s (All lso~ers)
K) tropropane
Si trotoluenp
Picric Acid
Cless 2!> Hydrorarbonsj Aliphatic,
Unseturated
(Al 1 Isomers)
Bulertiene
Styrene
Class 2fi Hydrocarbons, Aliphatic,
Setureted
Butane
Cyclohexene
Class 27 Peroxides and Hydrp-
peroKJdes Organic (All
iBomers)
Benzoyl Percrxide
Hydroqen Peroxide
Oilorocresol
Coal Is:
Creso]
Creosote
Class 26 Phenols, Crcsols
Hydroquinone
Nitrophenol
Phenol
Picric Acid
Resorcinol
Class 29 OrqanophospheteBj
'PliosphothioBtes, and
'Ptiosphodithioates
Ha lathi on
Parathion
Class 31 Epoxides
Cpichlorohydrin
Class 32 Combustible and
Siable Materials,
ftisccllaneous
Diesel Oil
Gasoline
Kerosene
Naphtha
turpentine
Class 33 Explosives
Benzoyl Peroxide
Picric Acid
Class 34
^ le Compounds
Acrylorutrile
Butadiene
Meths 1 Ai-rvlat*
-------
14-24
Table 14-9 (continued)
Cless 35 0« idi? ing Agpntj, Strong
Chloric Acid
Chr ex- ic Ac id
Silver Nitrate
Sodium Hypor^lnrite
Sulfur 1r ios ide
Class 36 Rediicinq Agents, Strong
Diarine
Hydrazme
Class 37 Hater and Hutures Containing Water
Aqueous solutions and mixtures
Water
Class 38 Water-Reactive Substances
A?et ic Anhvdr ide
*- - ;: otir or i: A: .c!
Sulfunc Acid
Sulfur Trioxide
Source: Hata>era, e_t a_l. , I960.
-------
14-25
0 Online chemical databases such as OHMTADS, CHEMTREC, CIS and
TOXLINE;
0 The manufacturer of a chemical;
0 The waste Generator; and
0 Manifests that accompany a waste.
A hazardous waste compatibility matrix has been developed that is
illustrated in Figure 14-4. Using this matrix, one can determine, in advance,
the potential for an incompatibility reaction. In this manner, the user can
avoid mixing two incompatible wastes and/or can develop a method of tank
decontamination that lessens the likelihood of such a reaction. It is
important to note, however, the matrix assumes the chemicals to be of TOO
percent concentration at standard temperature (25°C) and pressure (760 mr
Hg). Chances in these conditions are likely to affect the degree and type of
chemical reaction (s). One cra^bac1'. of this metnod is that incompatibility
reactions involving three chemicals are not ascertainable using the Figure
14-4 matrix.
If several classes of chemicals compose a waste stream, all non-negligible
pairs of classes in the two hazardous wastes must be tested using the
compatibility matrix process. In cases where the user is unsure of how much
of a particular chemical class is present and how significantly this class
will affect compatibility, it is best to assume incompatibility and proceed
with non-mixture and/or tank washing methods.
If chemical incompatibility is found for an unwashed tank system,
decontamination methods should proceed according to the type of compound found
in the unwashed system. Specific nethods of decontamination for storage tanks
are outlined in Table 14-10. Decontamination steps can begin when a tank has
been emptied. A tank system that contained wastes must be rinsed with a
solution compatible with the waste residues.
-------
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-------
14-27
TABLE 14-10
Storaae Tank Decontamination Methods
Eouicment
Tanks containing acids
Tanks containing bases
Tanks containino fl
Tanks containing chlorinated
wastes
Tanks containinc ?CEs
Neutralization tanks
Tanks containing solvents
Haloaenated solvent waste
tanks
Method of Decontamination
Drain and remove solids, caustic wash,
water rinse
Drain and remove solids, acid wash, water
rinse
Drain and remove solids, water rinse,
stean clean
Drain and remove solids, water rinse,
sterr clean
Triple solvent rinse (10% total tank
volu Tie/rinse)
Drain and remove solids, water rinse
Drain and remove solids, water rinse,
steam clean
Drain and steaTi clean
-------
14-28
The following hypothetical cases present examples of the method that
should be applied to determine chemical compatibility, utilizing the compati-
bility matrix of Fiaure 14-4.
Example 1
The receivina tank previously contained chromic acid. It is now proposed
that potassium cyanide be stored in this unwashed tank. From Table 14-8, it
can be determ;ned that chromic acid is in class 35 (strong oxidizing agents)
and potassium cyanide is in class 11 (cyanides). The letter abbreviation at
the point of intersection in Figure 14-4 indicates the likely reactions: heat
generation, as a primary reaction consequence, and explosion and toxic gas
generation as a secondary conseauence, resulting from the heat generation. It
can be concluded that these twr wa^te? are extremely incompatible. In order
to be able to store potassiu" t.'~-*,r- i'- t^h t = r-'- , all c^o-ic acid residues
must be removed and the tank fully decontaminated. The method of decontamina-
tion will involve draining the tan- , removing any solids, applying a caustic
wash, and rinsing with a high-pressure stream of water.
Example 2
A no-hazard situation may involve the addition of acetone (class 19,
ketones) to a tank that once contained acetaldehyde (class 5, aldehydes).
According to Figure 14-4, no reaction consequence is indicated, and the two
compounds are considered generally compatible.
14.2 Major Issue Points
0 Precautionary measures must apply to tanks and all ancillary
equipment.
0 Documentation of compliance with dissipation of hazard is required.
-------
14-29
0 All waste must be treated, mixed or rendered inert prior to or
immediately after placement in the storage tank, except in emergency
situations, or;
0 Facility design and operating characteristics are such that waste is
protected from any materials or conditions that may cause the waste
to ignite or react.
0 Treatment and mixture processes must be waste-specific.
0 Compliance with National Fire Protection Association protective
distance reouirements for tanks is essential.
0 Mixing of incompatible wastes in t^e same tank or placement of wast?
in a tank that once helc 3-. incoT3tible ^aste is not allowed, unle:-:- m
a hazardous reaction conseciuence can be prevented.
0 Complete chemical identification of waste characteristics and waste
compatibility must be determined in order to identify potential
reaction consequences.
0 An appropriate method of tank decontamination should be selected
based on the type of waste residues remaining in a receiving vessel.
-------
APPENDIX C
COMPLETENESS CHECKLIST
This section contains a checklist of items that must be included in a
RCRA Part B permit application. Use of this checklist is not a regulatory
requirement. However, its use, or use of a similar document, is strongly
recommended. The checklist will assist the reviewing agency, enabling a more
expeditious review of an application. Use of the checklist will also assist
the permit applicant, confirming that he is submitting a complete appli-
cation.
Each required information item is briefly stated. Regulatory citations
are provided that enable quick location of the full text of the regulation for
each required item. If no citation is indicated next to a specific item, the
last citation indicated above the item contains the regulatory requirement.
Space is provided so an applicant can indicate whether an item is
included in his permit application or does not apply. Space is also provided
so an applicant can record the page number or some other indication of where
an item can be found in the application.
-------
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o n
eu
n ->
Cv O
rt 3
O -
3 3
r~
o
00
^~
n
c
3
ri
_j
3
C
TO
s^.
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1
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