CALIFORNIA. DEPT, OF WATER RESOUECES.BULLETIN.

U.C.O. iR^

^ V

'/ STATE OF CALIFORNIA

The Resources Agency

Department of Wa ter Resources

BULLETIN No. 74-1

CATHODIC PROTECTION WELL STANDARDS

State of California

Copies of this bulletin at $2.00 each may be ordered fronStote of CaliforniaDEPARTMENT OF WATER RESOURCESP. 0. Box 388Sacramento, Colifornio 95802

MARCH 1973

NORMAN B. LIVERMORE, JR.Secretory for Resources

The Resources Agency

RONALD REAGANGovernor

State of California

WILLIAM R. GIANELLIDirecior

Department of Water Resources

nrh im>Ak "^ "'

AUTHORIZATION

The program under which this report was prepared is

authorized by Section 231 of the V/ater Code, State of California

which reads:

"231. The department, either independently or incooperation with any person or any county, state, federalor other agency, shall investigate and survey conditionsof damage to quality of underground waters, which conditionsare or may be caused by improperly constructed, abandonedor defective wells through the interconnection of strata orthe introduction of surface waters into underground waters.The department shall report to the appropriate regionalwater quality control board its recommendations for minimumstandards of well construction in any particular localityin which it deems regulation necessary to protection ofquality of underground water, and shall report to theLegislature from time to time, its recommendations forproper sealing of abandoned wells."

In 1967, the Legislature established a procedure for

implementing standards developed under Section 231 by enacting

Chapter 323, Statutes of I967, which added Sections I38OO through

13806 to the Water Code. Cathodlc protection wells were added to

these provisions in I968. In Section 138OO, the Department of

Water Resources' reporting responsibility is enlarged upon:

"13800. The department, after such studies and investi-gations pursuant to Section 231 as it finds necessary, ondetermining that water well and cathodic protection wellconstruction, maintenance, abandonment, and destructionstandards are needed in an area to protect the quality ofwater used or which may be used for any beneficial use,shall so report to the appropriate regional water qualitycontrol board and to the State Department of Public Health.The report shall contain such recommended standards for waterwell and cathodic protection well construction, maintenance,abandonment, and destruction as, in the department's opinion,are necessary to protect the quality of any affected water."

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FOREWORD

This is a companion publication toBulletin No. 7^ "Water Well Standards: State ofCalifornia", published in I968. The standards presentedin this report are issued as guides to the constructionand destruction of cathodic protection wells inCalifornia. Their purpose is to provide additionalprotection for the quality of our ground water resources.

The Department recommends that all countiesand cities consider enacting well construction ordinancesthat include both water wells and cathodic protectionwells. Such ordinances will comprise another step in thecontinuing effort to protect the usability ofCalifornia's ground water supplies.

We recognize that effective and usefulstandards must be periodically revised and updated toreflect both the degree of success achieved in theirapplication and changes in practice. Accordingly theDepartment will revise these standards as needed.

W. R. Gianelli, DirectorDepartment of Water ResourcesThe Resources AgencyState of CaliforniaFebruary 21, 1973

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TABLE OF CONTENTS

Page

AUTHORIZATION 2

FOREWORD, 3

ORGANIZATION, DEPARTMENT OF WATER RESOURCES 7

ORGANIZATION, CALIFORNIA WATER COMMISSION 7

ABSTRACT 7

CHAPTER I. INTRODUCTION 9

Cathodic Protection Wells 9

The Problem 13

Corrosion Coordinating Committees 18

Scope of Program and Report 19

CHAPTER II. STANDARDS 23

Part I. General 23

Section 1. Definitions 23

Section 2. Exemption Due to Unusual Conditions . 23

Section 3. Exclusions 23

Section 4. Special Standards 23

Section 5. Contractors 23

Section 6. Reports 24

Section 7. Temporary Cover 24

Part II. Well Construction 24

Section 8. Well Location with Respectto Pollutants 24

Section 9. Surface Construction Features .... 24

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TABLE OP CONTENTS (CONT'D)

Page

Section 10. Sealing the Upper or Near-Surface Annular Space 24

Section 11. Sealing-Off Strata 26

Part III. Destruction of Wells 30

Section 12. Purpose of Destruction 30

Section 13. Definition of "Abandoned" Well ... 30

Section l4. General Requirement 30

Section 15. Requirements for Destroying Wells . 30

CHAPTER III. CONSIDERATIONS IN APPLYINGTHE STANDARDS 35

General Standards 35

Construction Standards 36

Destruction Standards 39

APPENDIXES

Appendix A: DEFINITION OP TERMS 4l

Appendix B: BIBLIOGRAPHY ^5

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TABLE OP CONTENTS (CONT'D)

FIGURES

Figure PageNumber

1 Generalized Corrosion Situationand Cathodlc Protection 11

2 Typical Cathodic Protection Well(Deep Anode) 12

3 Surface and Shallow SubsurfacePollution of a Well andAdjacent Stratum l4

h Movement of Pollutant BetweenFormations Via a Well 15

5 Typical Deep Anode Welland Pollutants 17

6 Sealing Conditions - Upper Annular Space .... 25

7 Sealing-Off Strata Cases 1 and 2 28

8 Sealing-Off Strata Case 3 29

9 Well Destruction - Sealing Conditions 32

TABLES

TableNumber

1 Cathodlc Protection Requirementsfor Pipeline Safety l8

2 Reports Issued Under Water WellStandards Program CoveringSpecific Areas 21

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state of CaliforniaThe Resources Agency

DEPARTMENT OF WATER RESOURCES

RONALD REAGAN, GovernorNORMAN B. LIVERMORE, JR., Secretary for Resources

WILLIAM R. OIANELLI, DirectorJOHN R. TEERINK, Deputy Director

DIVISION OF RESOURCES DEVELOPMENT

Herbert W. Greydanus Division Engineer

James L. Welsh .... Chief, Environmental Quality Branch

Robert L. HcDonell Chief, Water ResourcesEvaluation Section

This report was prepared by

Edwin A. Ritchie . . . Associate Engineer, Water Resources

State of CaliforniaDepartment of Water ResourcesCALIFORNIA WATER COMMISSION

IRA J. CHRISMAN, Chairman, VlaallaCLAIR A. HILL, Vice Chairman, Redding

Mai Coombs Garbervllle

Ray W. Ferguson Ontario

William H. Jennings La Mesa

Clare Wm. Jones Flrebaugh

William P. Moses San Pablo

Samuel B. Nelson Northrldge

Ernest R. Nichols Ventura

Orville L. AbbottExecutive Officer and Chief Engineer

Tom Y. Pujlmoto, Staff Assistant

ABSTRACT

Water wells have been recognized as a means whereby the quality of ground

water can be polluted or otherwise Impaired. Cathodlc protection wells (or "deep

anodes") present similar hazards to ground water quality.

This problem can be alleviated by the proper design and construction of

new wells and the proper destruction of wells no longer In use. Standards for the

construction and destruction of cathodlc protection wells are presented and discussed.

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CHAPTER I. INTRODUCTION

Wells are commonly excavated toextract ground water or Injectwater into the ground. Thereare other types of wells, how-ever, less common than the waterwell, constructed for otherpurposes which penetrate andpass through the underlyingaquifers. One of these is thecathodic protection well, or"deep anode'' as it is called inthe corrosion industry.Cathodic protection wells housedevices used to alleviateelectrolytic corrosion of pipe-lines, tanks, and similarinstallations.

Water wells have been recognizedas a means whereby the qualityof underground waters can bepolluted or otherwise impaired.Such impairment is usually theresult of inadequate design orconstruction or of improperdestruction when the well is nolonger in use. Actually theconstruction of any type well,regardless of its purpose, tendsto disrupt the geologicenvironment

.

As the number of wells in anarea increases, the potential forimpairing ground water qualityIncreases. The solution to thisproblem is to see that wells aredesigned, constructed, andproperly destroyed so that theywill not cause deterioration ofground water quality.

If our ground water resourcesare to be effectively used, wemust protect their quality.Recognizing this, the CaliforniaLegislature enacted legislationdirecting the Department ofWater Resources to develop

recommendations for standardsfor the construction anddestruction of water wells(Section 231 of the CaliforniaWater Code). Later a procedurewas established for implementingsuch standards (Chapter 10 ofDivision 7 of the Water Code).In 1968, having concluded thatcathodic protection wells couldalso function as instrumentsfor the deterioration of groundwater quality, the Legislatureamended the Water Code toinclude such wells.

Bulletin No. 7^-1 was preparedin partial fulfillment of theDepartment's responsibilitiesunder the Water Code and is anextension of the Department'sBulletin No. Jh "Water WellStandards: State of California",February I968.

A detailed discussion of howwells may contribute to groundwater pollution Is presented inBulletin No. 7^. Therefore,only the highlights, andparticularly those pertainingto cathodic protection wells,are discussed in this bulletin.First, however, because manypersons know little about thecathodic protection well, someexplanation of its purpose andconstruction is presented.

Cathodic Protection Wells

Cathodic protection wells areinstalled to provide protectionfrom corrosion, primarily whereextensive conveyance andstorage facilities such as oil,natural gas, water and otherpipelines, powerlines, telephonecables, tanks, switchyards.

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control centers, etc. have beenconstructed. They are also usedto control corrosion In waterwells, because the cost of con-structing a large capacity waterwell is increasing, and extendingits life is an importantconsideration.

Corrosion, as used in thisbulletin, is defined as thedeterioration of metal byelectrochemical reaction withthe environment in which themetal is situated.* The processis illustrated in Figure 1,which depicts the deteriorationof a steel pipeline. The pipe-line is situated in a soil-waterenvironment in which the wateracts as an electrolyte. Asdissolved salts in the waterincrease, the resistance to theflow of electric currentdecreases (thus, saline water isan excellent electrolyte). This,coupled with a varying electricpotential on the surface of thepipe, establishes a flow ofcurrent from a cathode to ananode and causes the removal ofmetal from the anode. Theprocess gradually weakens thepipe, resulting in its eventualfailure.

Cathodic protection is under-taken to prevent or minimizecorrosive action by redirectingthe current to a substituteanode which then deterioratesinstead of the pipeline.

Note that chemical corrosion,which occurs when a specificcompound or element is presentin sufficient concentration tobring about removal of amaterial, is not considered here.Examples would be oxygen, carbondioxide or hydrochloric acid ina liquid solution flowingthrough a pipeline.

For a number of years, protec-tive anodes composed ofmaterials that deteriorateslowly have been installed at orclose to the surface of theground. Horizontal or shallowvertical anodes have certaindisadvantages, however, particu-larly in metropolitan areas orin areas of heavily concentratedfacilities, e.g., oil fields.In such locations, electricalinterference may be high. More-over, the installation of a largenumber of horizontal or shallowvertical anodes requires exten-sive right of way.

To offset these disadvantages,the vertical deep anode (cathodicprotection well) was developedand first used in the 19^0 's.

A typical deep anode, shown inFigure 2, is constructed by:

1. drilling a hole 6 to 12inches in diameter to thedesired depth;2. placing a string of anodesin the hole to designateddepths

;

3. backfilling the anodeinterval with a conductivematerial (usually granularcarbonaceous material);4. installing a small-diameter (about one-inch)plastic pipe to vent the gasesgenerated by the decompositionof the anode;5. backfilling the upper, orvent", interval with a non-conductive material (usually,a uniform, small-diametergravel), which provides afurther permeable medium formigration of gases, and preventscaving of the walls of thehole;6. installing a permanentcover over the well;7. electrically connecting

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GROUND SURFACE

SOIL- WATERACTION

CATHODIC AREA

REMOVAL OF METAL

ANODIC AREA

CORROSION OF PIPELINE

PIPELINE

CURRENT D-CCURRENTSURFACE

ANODE

CATHODIC PROTECTION

FIGURE I. GENERALIZED CORROSIONSITUATION AND CATHODIC PROTECTION

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RECTIFIER(DC Current Source)

GROUND SURFACE

ANODEINTERVAL

ELECTRICALCABLE

PIPE

NONCONDUCTIVE BACKFILL

VENT PIPE

- CONDUCTIVE MATERIAL

ANODES

FIGURE 2. TYPICAL CATHODICPROTECTION WELL (DEEP ANODE)

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the anode leads, and leads fromthe Installation to be protected,to a source of current.

Depths of these "deep anodes"normally range from 100 to 500feet. Installations less than50-feet deep are consideredshallow anodes.

The basic design may, of course,vary. For example, duringconstruction, casing may be usedin the uppermost section to holdback caving or sloughing mate-rials such as dune sand. How-ever, casing, which is used inthe water well to keep out sub-surface materials and to housethe pump mechanism, is notnormally used in a cathodicprotection well.

Now widely used, cathodicprotection wells have distinctadvantages over horizontal orshallow anodes. These are:

1. Right-of-way costs,particularly in congestedareas, are substantiallyreduced.2. Less incidence of cathodicprotection current interferencewith nearby unprotectedstructures. (This has evenmore future significanceconsidering the advent ofdirect current electric railsystems and d.c. high voltagetransmission systems with theirinevitable stray currentproblems.)3. Current is made availableto a much larger area of theprotected structure.

In California, most cathodicprotection wells are located inareas where undergroundconveyance systems are mostnumerous, i.e., (l) the SouthCoastal Area from San Diego toSanta Barbara, (2) the San

Francisco Bay Area, and (3) theoil-producing areas of theSouthern San Joaquin Valley andCentral Coast.

Only a few cathodic protectionwells have been installed in therest of California. For example,in the entire State north ofSacramento only an estimated25-50 wells are known to be inoperation.

The Problem

Any improperly constructed (ordestroyed) well can endangerground water quality in threeways. These are:

1. When the surface portionof the well is constructedwithout protective features,so that water may flow intothe well and subsequentlyinto the adjacent formation(Figure 3).2. When the annular space,that is, the space betweenthe outside of the casing (or,in the case of the cathodicprotection well, the vent pipe)and the wall of the hole lacksan adequate vertical seal, andsurface or shallow subsurfacewater may flow laterally intothe well and to the adjacentformation along the outside ofthe casing (Figure 3).3. When, during well construc-tion (or destruction), aquifersthat produce water of undesir-able quality are ineffectivelysealed off so that interchangeof water results in a signif-icant deterioration of thequality of water in one or moreother aquifers. In this casethe well provides a physicalconnection between aquifers(Figure 4).

A well that is intentionally or

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CASINGPOLLUTANT

FIGURE 3. SURFACE AND SHALLOW SUBSURFACE POLLUTIONOF A WELL AND ADJACENT STRATUM

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FIGURE 4. MOVEMENT OF POLLUTANTBETWEEN FORMATIONS VIA A WELL

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inadvertently used for thedisposal of wastes can also be asource of impairment to waterquality. However, cathodicprotection wells are seldom soused, simply because they have asmall opening at the surface.On the other hand, water issometimes introduced intocathodic protection wells inlocations where natural electro-lytes are lacking, to keep thesystem functional. Should thewater so introduced be ofquestionable quality, thispractice could be considered aswaste disposal. Fortunately,the volumes of water involvedare probably small, and the waterdoes not usually migrate appre-ciably.

Cathodic protection wells con-structed as described on Page 10are particularly conducive tothe lateral and vertical movementof fluids. The granular back-filled excavation is uniformlypermeable and thus will readilyconvey pollutants. Consequently,the three conditions thatcontribute to water qualityimpairment Just outlined canbecome a reality. This isdepicted in Figure 5.

Because of increasing concernfor the safety of pipelines thattransport natural gas and otherhazardous materials, more andmore cathodic protection wellsare being constructed. TheNatural Gas Pipeline Safety Act(Public Law 90-481) adopted bythe Congress in August I968directs the United StatesDepartment of Transportation toestablish safety regulationsgoverning the transportation ofnatural and other gases by pipe-line. These regulations {&)*

*See Appendix B, Item 8 forcomplete title.

specify that all buried or sub-merged pipelines be cathodicallyprotected as shown in Table 1.

These requirements have also beenadopted and reiterated by theCalifornia Public UtilitiesCommission (1). Therefore, with-in the next few years, considera-bly more cathodic protectionwells will probably be installedin California.

Of immediate concern are cathodicprotection wells no longer inuse. The present practice is toremove the electrical connectionsand abandon the well. Such awell is a potential intermediaryfor the travel of pollutantsunderground and should bedestroyed.

The life of the anode in acathodic protection well willdetermine the useful life of thewell. Anodes are usuallydesigned to last about I5 to 20years. Fortunately, only a fewolder wells exist at present,but eventually many wells willbe abandoned. However, in recentyears there has been a tendencyto design and construct wells sothat the anodes can be replaced,thus obviating the need to drilla new hole and extending the lifeof the well several times.

Cathodic protection wells arealmost always backfilled andtherefore are not a hazard tochildren and animals, as areabandoned water wells. However,variations in design andincreasing vent pipe (or casing)sizes could pose a safetyproblem as, for example, shouldthe diameter exceed eight Inches.

In summary, as stated inBulletin No. 7^:

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FIGURE 5. TYPICAL DEEP ANODE WELL AND POLLUTANTS

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TABLE 1

CATHODIC PROTECTION REQUIREMENTSFOR PIPELINE SAFETY*

Condition of Pipeline or LocationDate Pipeline : Date Protection

Installed : Required

1. Transmission Lines witheffective external coating.

2. In areas where active corrosionis found:

a.

b.

c.

3. New

Bare or ineffectivelycoated transmission lines.Bare or coated pipes atcompressor, regulator ormeasuring stations.Bare or coated distributionlines.

Prior to 8/1/71 8/1/74

Prior to 8/1/71 8/I/76

A^ter 7/31/71 Within one yearafter completion

Adapted from regulations of U, S. Department of Transportation. (8)

"Irrespective of the prob-ability of occurrence andwhich form of deteriorationtakes place, California'sground water supplies must bepreserved and protected tomeet the increasing demandswhich are being made on them.Moreover, while the wellconstruction industry,advisory groups, and regula-tory agencies obviously intendto prevent any impairment ofthe quality of the State'sground water supplies whichmight result from improperlyconstructed or 'abandoned'wells, there appears to be nobroad, uniform approach to thedevelopment of the means ofsuch prevention in California.It follows then that theresolution of this dilemma

requires the development ofstandards for ... well construc-tion and destruction, whichwill, if followed, assure theprotection of the quality ofthe State's ground waters ..."

Corrosion CoordinatingCommittees

Because the various networks ofdeep anode installations, likethe systems they protect, criss-cross one another, seriouselectrical interference problemscan develop. For example, thecurrent produced at one anodemay affect an adjacent anode orfacility. Moreover, in congestedareas many "stray" currents areproduced. In one instance, theuse of salt as a deicer on

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electric street railways In thenortheastern United Statescontributed to a lowered resist-ance between the track and ground,thus Increasing the magnitude ofcurrents flowing In the soil.The problem was partially solvedby the advent of the trolley busand liquid fuel driven bus (3).However, with the trend towarddirect current electric railsystems and high-voltage trans-mission lines, this aspect of thestray current problem Is renewed.

To overcome these and otherproblems, corrosion coordinatingcommittees have been formed inmany areas. Most are affiliatedwith the National Association ofCorrosion Engineers, and atpresent there are 33 suchaffiliates in the United States.Four are located in California.They are

:

1. The Joint Committee for theProtection of UndergroundStructures in Alameda andContra Costa Counties.2. Southern California CathodicProtection Committee (coveringall of Southern California southof San Luis Obispo, Kern andInyo Counties except San DiegoCounty)

.

3. The San Francisco Committeeon Corrosion (including a smallSortion of San Mateo County).

.Central California Cathodic

Protection Committee (coveringall of Central California, theSacramento Valley Counties andthe western Sierra Nevadamountain counties south ofPlumas County).

A fifth but informal group, theSan Diego County UndergroundCorrosion Control Committee,deals with that area. There areno groups functioning in thecoastal counties north ofSan Francisco or in the north-

eastern portion of the State,

These committees represent themajority of the utilities andother companies who installdeep anodes. The members keepone another apprised of theirorganization's plans andcoordinate the installation andoperation of cathodic protectionfacilities, thereby minimizingproblems of interference fromstray currents. Unfortunately,not all those who install andoperate cathodic protectionfacilities are allied with acorrosion coordinating committee.Those not associated with acommittee are largely Individualsor local agencies (such as schooldistricts) who are usuallyunaware of the existence of otherInstallations. Often such afacility will produce currentsthat Interfere with nearby deepanode installations. In suchcases this may reduce or actuallynullify the effect of othercathodic protection installations,

Scope of Programand Report

The purposes of the Department ofWater Resources' Well StandardsProgram are to (1) formulaterecommendations for standards toprotect the quality of theState's ground water resourcesfrom impairment that might resultfrom inadequately constructed,defective, or improperly abandonedwells; and (2) encourage theestablishment of these standardsthroughout the State.

The general statewide water wellstandards developed are intendedfor use throughout the State andunder the majority of conditionsencountered. However, in anumber of areas specific infor-mation, principally the

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definition, both vertically andareally, of affected or endan-gered aquifers, is needed sothat the standards can beapplied. For this reason,special studies have been made,and others will be conducted inthe future, to develop thisinformation for certain areasof the State. Publicationsreporting the results of thesestudies, together with recom-mendations for the applicationof standards, have been issuedfor 10 areas in California.These publications are listedin Table 2.

This report presents recommendedstandards for the constructionand destruction of cathodicprotection wells (Chapter II)together with a discussion oftheir application (Chapter III).The standards contained in thisreport are intended to be usedthroughout California. Theinformation presented in thereports listed in Table 2 canbe used as an aid in applyingthese standards in the 10 areasstudied.

Technical terms concerningground water and wells are

frequently misunderstood. Inan effort to clarify such terms,a list of definitions ispresented in Appendix A.

Publications reviewed in prepa-ration of this report are listedin Appendix B. References topublications concerning thedevelopment and protection ofground waters and water wellconstruction are contained inBulletin No. 7^.

In accordance with Section 138OOof the Water Code, the Departmentof Water Resources has recom-mended to the appropriateCalifornia Regional Water QualityControl Boards and the StateDepartment of Public Healththat water well standards beestablished and enforced in the10 areas listed in Table 2.Ordinances governing wellconstruction and destructionare in effect in five of theseareas and are being developedin the other five. In additionseveral counties have taken theinitative and adopted similarordinances. It is anticipatedthat all California counties andcities will eventually enactsuch ordinances.

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TABLE 2

REPORTS ISSUED UNDERWATER WELL STANDARDS PROGRAM

COVERING SPECIFIC AREAS

Area of Study

CHAPTER II. STANDARDS

The standards presented in thisreport for the construction anddestruction of cathodlc protec-tion wells are considered satis-factory under most conditionsthroughout the State. However,geologic and ground waterconditions vary widely, and todevise standards for everyconceivable situation would havebeen impossible. Accordingly,provision has been made fordeviation from the standards andin their application with theobjective of providing groundwater quality protection equalto that provided by thesestandards.

The standards recommended aresimilar to those for water wellsset forth in Bulletin No. 7^.Because certain general waterwell standards apply equally tocathodic protection wells, theyhave been repeated verbatim.The wording in others has beenslightly modified. The arrange-ment is parallel to those forwater wells.

Part I. General

Section 1. Definitions

A. Cathodic Protection Well . Asdefined in Section 13711 of theWater Code:

"...means any artificialexcavation in excess of 50 feetconstructed by any method forthe purpose of installingequipment or facilities for theprotection electrically ofmetallic equipment in contactwith the ground, commonly refer-red to as cathodic protection."

B. Enforcing Agency. An agency

designated by duly authorizedlocal, regional, or stategovernment to administer laws orordinances pertaining to wellconstruction.

Section 2. Exemption Due toUnusual Conditions

.

If the enforcing agency findsthat compliance with any of therequirements prescribed hereinis impractical for a particularlocation because of unusualconditions, it may prescribealternative requirements whichare "equal to" these standardsin terms of protection obtained.

Section 3. Exclusions .

The standards prescribed InPart II, "Construction", donot apply to test holes orexploratory holes. However.Part III, "Well Destruction*^,does apply to test holes andexploratory holes.

Section 4. Special Standards.

In locations where existinggeologic or ground waterconditions require additionalor more restrictive standardsthan those described herein,such special standards may beprescribed by the enforcingagency.

Section 3. Contractors .

Cathodic protection wells shallbe constructed by contractorslicensed in accordance with theprovisions of the ContractorsLicense Law (Division 3,

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Chapter 9, of the Business andProfessions Code unless exemptedby that act

.

Section 6. Reports.

Reports concerning the construc-tion of cathodic protectionwells shall be filed In accord-ance with the provisions ofSections 13750 through 13755(Division 7, Chapter 10,Article 2) of the Water Code.

Section 7. Temporary Cover .

During periods when no work Isbeing done on the well, such asovernight or while waiting forsealing material to set, the welland surrounding excavation. Ifany, shall be covered. The covershall be sufficiently strong andwell enough anchored to preventthe Introduction of foreignmaterial into the well and toprotect the public from apotentially hazardous situation.

PART II. Well Construction

Section 8. Well Location withRespect to Pollutants

^

A. In congested urban areas orwhere the cathodic protectionwell is located within 100 feetof a source of pollution (sewer,septic tank, etc.) the annularspace shall be sealed to a depthof at least 50 feet below theland surface (as described InSection 10, following).

B. Where in the opinion of theenforcing agency adverse condi-tions exist, wells locatedfurther than 100 feet fromsources of pollution shall besealed as prescribed inParagraph A, above, or the depthof seal Increased.

Section 9.^Features.

Surface Construction

A. The top of the well shall beprotected against the entrance ofsurface water draining from thesurrounding land by installationof watertight caps, covers, plugsor similar devices.

In drainage ways, exclusive ofhighways, streets, paved surfaces(such as parking lots, equipmentyards, etc.), sidewalks, and thelike, the top of the well shallterminate above, or be otherwiseprotected against, known condi-tions of flooding.

B. When extended above groundsurface, the vent pipe shall beterminated at the rectifierhousing or other protectivehousing at an elevation which isabove known conditions of flood-ing.

Section 10. Sealing the Upperor Near-Surface Annular SpaceT

The space between the well casingor vent pipe and the wall of thedrilled hole (the annular space)shall be effectively sealed toprotect against contamination orpollution by surface and/orshallow, subsurface waters, asset forth below.

A. Sealing Conditions , Follow-ing are requirements to beobserved in sealing the annularspace:

1. The space shall be filledwith sealing material (Para-graph B below) to a depth ofat least 20 feet, or as pre-scribed in Section 8 of thesestandards, or to the minimumdepth (greater than 20 feet)as prescribed by the enforcingagency (Figure 6).

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VENT_ORCASING

ANODES

GROUT SEAL

NONCONDUCTIVEBACKFILL

CONDUCTIVEMATERIAL

A. GENERAL REQUIREMENT

C^