THE RESOURCES AGENCY OF CALIFORNIA Department of Wa ter Resources BULLETIN No. 74 RECOMMENDED MINIMUM WELL CONSTRUCTION AND SEALING STANDARDS FOR PROTECTION OF GROUND WATER QUALITY STATE OF CALIFORNIA Preliminary Edition JULY 1962 EDMUND G. BROWN WILLIAM E. WARNE ^ Administrafor Governor .,, „ . , ^ , , The Resources Agency of California State of California ond Director Department of Water Resources State ot California THE RESOURCES AGENCY OF CALIFORNIA Department of Wa ter Resources BULLETIN No. 74 RECOMMENDED MINIMUM WELL CONSTRUCTION AND SEALING STANDARDS FOR PROTECTION OF GROUND WATER OUALITY STATE OF CALIFORNIA Preliminary Edition JULY 1962 EDMUND G. BROWN Governor State of California ctt^rarv WILLIAM E. WARNE Adminisfrator The Resources Agency of California and Direcfor Department of Water Resources ■iTY Of i;AT,TPr)1?Mlv PREFACE The mlnimtmi standards presented in this report are issued as pi^- liminary gioides to good practice for those engaged in the drilling of wells and to assist cities and counties in California in the regulation of water well construction. Covinties ajid cities which have not already done so, are encouraged to enact water well construction ordinances to protect the qiiality of ground water supplies in their areas. After s\ii'ficient time has elapsed so that interested state and local I "agencies and members of the water well drilling industry may consider and comment upon the recommended stemdards presented in this report, the Department of Water Resotirces will conduct hearings prior to issxiing these standards in final form. This procedure should take appioximately two years. During these hearings, it would he appropriate to consider amendments to Section 7076 of the Water Code. This report has been developed after constiltation with the State Department of Public Health, Bureau of Sanitary Engineering. A set of tenta- tive public health standards of well construction has also been in the process Of developaent jointly by the State Department of Public Health and the California Conference of Local Health Officers. These proposed standards, now being \ised by some local health departments on a trial basis, are appended to this report. iii TABLE OF CONTENTS Page FRONTISPIECE ii PREFACE iii ACKNOWLEDGMENT .' ix ORGANIZATION, DEPARTMENT OF WATER RESOURCES X ORGANIZATION, CALIFORNIA WATER COMMISSION xi CHAPTER I. INTRODUCTION 1 Authorization .' .* 1 Related Investigations and Reports 3 Statement of the Problem 3 Scope of Investigation and Organization of Report 5 CHAPTER II. GENERAL OCCURRENCE AND NATURE OF GROUND WATER IN CALIFORNIA 9 Water-bearing Materials 9 Sedimentary Deposits 9 Volcanic Rocks 11 Nonwater-bearing Materials 12 Subsurface I^drologic Conditions 12 CHAPTER III. QUALITY OF GROUND WATER AND ITS IMPAIRMENT 17 Characteristics of Ground Water Quality i?fS»^i,« * • ^"^ Sources of Impainnent to a-ound Water Quality 19 Surface Water 21 Deep-seated Waters 22 Sewage and Industrial Wastes 23 Sea Water 26 Other Sources 27 ▼ TABLE OF CONTMTS (continued) Page CHAPTER IV. WATER WELL CONSTRUCTION 29 Well Construction Methods 30 Drilled Wells 3I Dug, Bored, Driven, and Jetted Wells 33 Construction Featxires Related to Protection of Ground Water Qviality ...,,,. 35 Well Location 35 Surface Feattires 39 i Openings Into Well Casing 39 Well Pits 1*2 Pump Houses h2 Casing euad Annular Space . h2 Casing Material 43 InstsiUation of Casing » , , . k^ Sealing Annular Space ^7 Gravel-packed Wells rs * » » > ^9 Sealing-off Strata 50 Well Development . . . 5I Well Disinfection 52 Well Abandonment 53 Legal Powers and LiMtations of the State and Local Agencies with Respect to Ground Water and Water Wells 55 CHAPTER V. RECOMMENDED MINIMUM STANDARDS FOR WATER WELL CONSTRUCTION AND DESTRUCTION OF WELLS 57 Recommended Standards for Water Well Construction 58 Well Location 58 vi TABLE OF CONTENTS (Continued) Page Sanitary Requirements 59 Casing and Annular Space , . . ; 61; Casing Material , 6U Installation of Casing 6k Gravel-packed Wells 6ii Sealing-off Strata 66 Well Development 66 Water Quality Sampling 66 Recommended Standards for Destruction of Wells ...... 6? Water Well Drillers' Report 68 CHAPTFIR VI. SUMMARY 71 Occurrence and Nature of Ground Water in California 71 Quality of Ground Water and Its Impairment 72 Water Well Construction , 72 Recommended, Minimum Standards for Water Well Construction and Destruction of Wells 7li TABLES Table No. 1 Minimum Recommended Distances Between Wells and Sources of Contamination 38 2 Chlorine Compound Required to Dose 100 Feet of Water-filled Casing at $0 Parts per Million 63 3 Suggested Minimum Thicknesses for Steel Water Well Casing 65 vii TABLE OF CONTENTS (continued) FIGURES Figure No. Page 1 Diagraiiinatic Cross Section Sho-wing Free, Confined, and Perched Ground Water Conditions ik 2 Effect of Reversal of Ground Water Gradient Near a Well Due to Pumping 37 3 Surface Features of a Proper Water'Well Installation I4.I k The Well Proper (Typical) kh 5 Properly Sealed Annular Sjjace 60 APPENDIXES A Bibliography A-1 B Definition of Terms B-1 C Water Quality Criteria C-1 D Proposed Standards for Public Health Protection of Community Water Supply Wells of State of California, Department of Public Health, Bureau of Sanitary Engineering D-1 E Summary of Water Well Construction and Sealing Ordinances in California E-1 F Legal Powers and Limitations of the State and Local Agencies With Respect to Ground Water and Water Wells (Unpublished) F-1 G Suggested Methods for Sealing the Upper Portion of the Annular Space and for Sealing-off Strata G-l viii ACKNOWLEDGMENT Valuable assistance and cooperation were received from agencies of the federal government and of the State of California, from cities and counties, from public and private agencies, and from individuals. This cooperation is gratefully acknowledged. We are grateful to the many water well drillers who provided informa- tion and made recommendations pertaining to water well construction and sealing; and, we wish to thank the counties and cities that provided information regard- ing local regulations governing well drilling and sealing. Special acknowledgment is made of the assistance and cooperation of the California State Department of Public Health, Bureau of Sanitary Engineering. Cooperation of the following organizations is also gratefully acknowledged: Associated Drilling Contractors Water Well Drillers' Association of Southern California, Inc. Kaiser Steel Corporation United States Steel Corporation IX STATE OF CALIFORNIA THE RESOURCES AGENCY OF CALIFORNIA DEPARTMENT OF WATER RESOURCES EmUND G. BROWN, Governor WILLIAM E. WARNE, Administrator, The Resources Agency of California and Director, Department of Water Resources ALFRED R. GOLZE, Chief Engineer DIVISION OF RESOURCES PLANNING William L. Berry ^ Chief Wesley E. Steiner . • Chief, Planning Management Branch This report was prepared under the supervision of Arthur J. Inerfield Senior Engineer, Water Resources by Edwin A. Ritchie , Assistant Civil Engineer Geologic portions of this report were prepared by Robert E, Thronson Associate Engineering Geologist CALIFORNIA WATER COMI'IISSia] RALPH M. BRODY, Chairman, Fresno WILLIAM H. JENNINGS, Vice Chairman, La Mesa JOHN W. BRYANT, Riverside JOHN P. BUNKER, Gustine IRA J. CHRiSMAN, Visalia GEORGE FLEHARTY, Redding JOHN J. KIl^G, Petaluma NORRIS POULS(»I, Los Angeles MARION R. WALKER, Ventura WILLIAM M. CARAH Executive Secretary GEORGE B. GLEASON Principal Engineer CHAPTER I. INTRODUCTIOJ Each year thousands of new water wells are constructed throughout the State and numerous wells are "abandoned," If these wells are not properly con- structed initially, they may not produce a suitable quality water for domestic purposes. Further, if wells are not satisfactorily reconstructed yihen defective or inadequately destroyed, they may permit impaiment of the quality of ground waters detrimental to one or several intended uses, A properly constnicted or adequately sesded well should maintain or restore, as far as possible, those subsurface conditions vrfiich existed pidor to construction of the well and vriiich prevented the entrance of waters of unsanitary suid inferior mineral quality into usable ground water supplies. Authorization Impairment of the qucility of ground waters of the State through im- proper construction or abandonment of wells is only one aspect of the water pollution problem in California, Concern over water pollution caused the Legis- lature to conduct extensive public hearings on the problem during the late 1940' s. Subsequently, a number of water pollution control acts were eidopted. Among these was legislation directing the Department of Water Resources to for- mulate recommendations for standards of water well construction and sealing. This legislation was enacted as Chapter 1552, Statutes of 1949, now Section 231 of the Water Code, State of California, Section 231 reads as follows: "231, The department, either independently or in cooperation with any person or any coxmty, state, federal or other agency, shfiuLl investigate and survey conditions of damage to quality of underground waters, which conditions are or may be caused by improperly constructed, abandoned or defective wells through the interconnection of strata or the introduction of surface waters into xmderground waters. The depart- ment shall report to the appropriate regional water pollution control board its recommendations for minimum standards of well construction in any particular locality in which it deems regulation necessary to protec- tion of quality of underground water, and shall report to the Legislatxxre frcm time to time, its recommendations for proper sealing of abandoned wells," -1- In addition to the Department of Water Resources, the State Department of Public Health has a concurrent interest in problems caused by improperly con- structed, defective, or "abandoned" wells. This interest is evidenced in the "Pxire Water Act" (Division 5, Chapter 7 of the Health and Safety Code, State of ;-.^ in' California, Added by Chapter 992, Statutes of 1947), which deals with the health aspects of public water supplies. Under this authorization, the State Board of Public Health, in granting permits to utilities for supplying water for domestic purposes, must find that under all the circumstances it is pure, vrfiolescane, and potable and does not endanger the lives or health of human beings. Further, the State Board of Public Health may adopt and enforce rules and regulations for the State Department of Public Health to use in the execution of its duties. Al- though the Department of Public Health is concerned about the quality of the water produced by wells for domestic purposes, particularly vAiere its responsi- bility to public water supplies is involved, to date no regulations have been drawn by the State Board of Public Health pertaining to dcmestic water well construction, ■ - ff£ot! j- • - ' ■■> In broad terms, the responsibility of the Department of Water Resources is to advise the Legislature and the appropriate state agencies with regard to the maintenance of the quality of water as it occurs in underground formations, including pix>tection against adverse effects caused by improper well constmc- tion or abandonment, and which ^plies to all wells irrespective of purpose. The responsibility of the State Department of Public Health relates essentisLLLy to protecting the quality of water that is withdrawn from a water-bearing formation and used for domestic purposes, even if the purpose for which the well was originally constructed was other than for domestic purposes. This report was prepared in cooperation with the State Department of Public Health, as part of a continuing program of the Department of Water Resources for discharging its responsibilities under the provisions of Section 231 of the Water Code. -2- Related Investigations and Reports Numerous publications related to construction of water wells and to development, use, and protection of ground waters have been reviewed in prepa- ration of this report. They are listed in Appendix A in alphabetical order by author. Reference is made to these publications in the text by means of numbers in parentheses; e.g. v-*-'. Investigations have been made and are being conducted in certain areas of the State to formulate recommended standards for water well constiniction and sealing similar to those in this report, but designed sp)ecifically for these localities. These local reccmmended standards will, in the future, be based upon the general statewide standards presented herein, modified and augmented in accordance with local conditions. The depai^anent has completed one such report published as B\illetin No, 62 (lA^), and is preparing reports for Alameda and Del Norte Counties, and for the West Coast Basin area of Los Angeles County(l^), In order to insure that the technical terms used in this report are coapletely understandable, a list of definitions is presented in Appendix B, Statement of the Problem Whenever a well has been inadequately constructed, is defective, or is improperly destroyed, it can contribute to the deterioration of the quality of ground water. The deterioration in quality, depending on the source and type of deterioration and the surrounding geologic conditions, can affect either the water immediately adjacent to the well in question, or to a group of closely adjacent wells, or a much larger quantity of water, pei^iaps even a segment of an entire ground water basin. While the latter condition is mare encompassing, the deterioration of the quality of water produced by an individual well, or groups of closely adja- cent wells, is the most common and the most significant from the stauidpoint of public health. Underground sources of supply have been responsible for a -3- sizable portion of the outbresJcs of the water-borne diseases reported in the United States. Most of these outbreaks occurred where shallow wells were so poorly constmicted that the allowed contaminants to enter the well* The contaminants entering improperly constructed wells are not limited to disease organisms or, for that matter, are not related to health problems alone. Literature ^^-^' on the subject is replete with examples of undesirable chemicals, some toxic and S(^e nontoxic, originating in waste waters which were, in one way or another, allowed to enter wells with the results that the water in wells a short distance away was adversely affected. The mechanism of water quality impairment in larger portions of a ground water basin or in an entire basin, because of faulty wells, is not so well defined. In those instemces where the quality of water in a segment of ground water basin has been impaired, an additional number of factors has been involved, and wells have served primarily to facilitate the impairment. The most noteworthy examples in Csilifomia of deterioration of water quality in a sizable portion of a ground water basin are those coastal ground water basins which have been intmded by that massive source of degradation — the ocean* So far as is known, inadequately constructed or improperly abandoned wells have not yet been found to be the sole cause of water quality degradation, where a sizable portion of a California groiind water basin has been involved. In fact, there is some doubt that entire ground water basins can be affected in this way, unless there existed an extreme condition of closely spaced, faulty wells constantly supplied by large volumes of pollutants. However, the construc- tion of thousands of additional wells in California each year, coupled with the fact that many of them are becoming more-closely spaced and an increase in the number of wells vrtiich can be expected to fall into a state of disrepair, indicates that the potential for impairing the quality of segments of, or even entire, basins continues to grow. Irrespective of the probability of occurrence and which form of dete- rioration takes place, it is becoming importamt that the usability of our present water supplies be preserved and protected to meet the increasing demands which are being made on them. Furthermore, to construct wells carelessly and to make them so cheaply as to be short-lived purely to keep the price down is strong evidence of shortsightedness on the part of those who have most to gain fran the maintenance of high quality ground water, the well user and the well driller. Should such wells become defective, they could very well lead to deterioration in some degree of the quality of ground waters, with possible risk of hazard to public heeilth and safety and of econcxnic loss. To prevent such conditions from occ\irring, effec- tive measures are necessary to assure that wells constructed in the State conform to reasonable standards which provide for long usable productive life and effective abandonment. At present, there are no state laws directly protecting the quality of water produced by wells or of ground water through regulation of water well constimction and sealing. Accordingly, minimum stsmdards for well construction and abandonment, applicable under all conditions foimd in the State, shoiild be developed. In addition to providing for the protection of the quality of ground water, these standards must be capable of execution by the average competent well driller using ordinary equipment and commercially available materials, and they also must not impose an undue financial burden upon the owner of the well or upon the driller. Finally, these standards must be enforceable. Scope of Investigation and Organization of Report The purpose of this statewide investigation is to formulate recom- mendations for minimum standards to protect the quality of ground water frdiich temporarily prevents caving. The cable tool , or percussion, method employs a string of tools sus- pended from a cable. A heavy bit on the end of the cable is alternately raised and dropped, thus breaking and crushing material at the bottom of the hole into small fragments. The reciprocating motion of the drilling tools operating in water mixes the loosened material into a "sludge." This sludge is removed from the hole periodically by a scow, bailer, or sand pump. Normally, the casing is forced or driven down as the drilling progresses. In addition to the methods of drilling described above, certain inno- vations of these methods as well as new methods have been developed which may some day become widespread in use. Of particular interest are reverse circula- tion rotary drilling and the "down-the -hole -hammer" or "mole" drill method. Reverse circulation rotary drilling, which is a variation of the con- ventional rotary method, was developed a number of years ago. Only within the -32- last ten years, however, have commercial rigs, designed for this purpose, been available. In reverse circulation rotary drilling, mud additives are seldom used. In this procedure, drilling fluid is circulated down the well and up through the drill pipe reverse to the direction used in the conventional rotary method. This method is generally confined to the drilling of large diameter wells, and is restricted to locations where an ample supply of water is available . In the "down-the-hole-hammer" method of drilling, compressed air not only serves as the source of drilling power but also provides the means for re- moving the cuttings from the hole. A pneumatic hammer connected to a rotary "string of tools" pulverizes the material being cut. The fine cuttings produced are blown up the hole. The method is particularly adapted to small diameter wells drilled in hard rock. Dug, Bored, Driven, and Jetted VJells Dug wells are excavated with hand tools such as a pick and shovel, or with mechanical equipment such as a clam-shell bucket. To prevent caving, this tjrpe of well is usually "curbed," or cased, during construction, or immediately after the excavation is completed. Curbing usually consists of concrete, brick, metal, or wood. Dug wells are seldom constructed to any appreciable depth below the water table because of difficulties encountered in digging and curbing. They are generally larger in diameter than drilled wells, seldom less than two feet, and are commonly from three to five feet in diameter. The radial well, or horizontal water collector ~ commonly referred to I as a Ranney well — is a dug well consisting of a reinforced concrete shaft, or caisson, from which horizontal intake pipes and screens project radially. The concrete caisson is on the order of 15 feet in diameter, and the intake pipes, which are jacked hydraulically into the formation through prepositioned portholes -33- in the caisson, are usually 6 or 8 inches in diameter (29). The length of the individual radial pipes and screens varies from 100 to 1;50 feet, depending on water-bearing properties of the materials penetrated. Radial wells are gen- erally located near rivers, with the intake screens drawing primarily on water infiltrating from the river. Bored wells are constructed with hand-operated or power-driven augers. Boring is done by turning the auger in the hole until the cutting tool is filled with excavated material. The auger is then removed from the hole and emptied. This process is repeated until the desired depth is reached. This type of con- struction is oiten used where small quantities of water are desired, and where water can be obtained at relatively shallow depths. However, small diameter wells have been sunk several hundred feet by this method. A driven well is constructed by driving a series of pipe sections into water-bearing materials. A pointed screen or "drive point," is fitted to the end of the first pipe section to facilitate driving and to permit entrance of water into the pipe. The pipe is driven into the ground by sledge, maul, or power-driven hammer. After the initial section has been driven, succeeding sec- tions are jointed and driven until the desired depth is reached, or further progress is prevented by resistance of the formations. Pipe diameters are com- monly 1^ to 3 inches, and may range up to 8 inches. Depth of driven wells is limited by the properties of the water-bearing materials encountered and by the fact that the small diameter pipes preclude the use of large capacity pumps. Basically, a jetted well is constructed by the erosive action of a jet of water. Water is fed under pressure through a hollow drill pipe and drill bit against the bottom of the hole. As the jet loosens the material, the cuttings are carried out the top of the hole by the water rising in the hole. Casing is usually sunk as the drilling proceeds, following closely behind the drill bit. -3U- Generally, after the casing has reached the desired depth, the well pipe with a well screen attached is inserted in the driven casing and lowered into the well. The casing is then pulled, leaving the well screen and pipe in the ground ready for use. Construction Features Related to Protection of Ground Water Quality To prevent the impairment of ground water quality by the entrance of foreign material and of contaminated or other undesirable water into well casings, special attention should be given to certain features of water well construction. It should be pointed out that these features do not, in themselves, preclude im- pairment to water quality. Their purpose is to merely prevent, either partially or completely, impairing agents from entering and mingling with the water in the well or aquifer. Invariably, it is the lack of the necessary features, or inad- equacies in their construction, that result in problems of ground water quality impairment . Presentation is made for each pertinent featvire of well constniction, including a description of the specific feature and its relation to the protec- tion of ground water quality. Where necessary, summary statements of existing practices, ordinances, and recommendations are included. It is not intended to cover all details of well construction or enumerate the variety of methods used in each instance. A number of the features discussed pertain primarily to the health aspects 'of quality protection, and others pertain to prevention of chemical impairment. Well Location The location of the well, of course, is the first feature to be con- sidered when planning the actual facility. Authorities in the field of water -35- supply and sanitation generally agree that water wells should be located a "safe" distance from potential sources of contamination. They also recognize that many local factors must be considered in determining safe distance. Such determination involves evaluation of the character and location of the sources of potential contamination, permeability of the geologic materials betvreen the ground surface and the water-producing aquifer, depth to ground water and its direction of move- ment, physical character of the water-bearing materials, and the effect of well pumping on the direction of ground water movement. Greater distances from sources of contamination are required in areas where permeable materials directly overlie ground water than in areas where there is clay or other materials of low permeability. Wells should be located up the ground water gradient from sources of contamination so that any contaminating material that reaches the water will be carried away from the well. In this regard, consideration should also be given to a possible local reversal of the areal ground water gradient in the vicinity of a well due to pumping. When water is withdrawn from a well, a drawdown cone of depression is formed in the water surface surrounding the well; and ground water in the area of this cone flows toward the well. Figure 2 illustrates the drawdown conditions. The Federal Housing Administration (FHA.), the United States Public Health Service (USPHS), and the Joint (Federal) Committee on Rural Sanitation, 19^0 (Jt. Comm.) have formulated recommendations regarding minimum distances be- tween water wells and sources of contamination. These recommendations are sum- marized in Table 1. -36 Cone of Depression resulting from Withdrawal of Water when Pumping. I Figure 2 EFFECT OF REVERSAL OF GROUND GRADIENT NEAR A WELL DUE TO WATER PUMPING ■37- TABI£ 1 MINIMUM RECOMMENDED DISTANCE BETWEEN WELLS AND SOURCES OF CONTAMINATION (In feet) Sources of Contamination FHA Agency- Drilled or Driven Dug or Bored Joint Commission USPHS Pit Privy Septic Tank 100 50 150 50 50 (50 feet from source of contamination Sewer — — 50 Watertight Cast Iron 10 20 — Vitrified Clay, Concrete 50 50 «■«««• Sewage Disposal Field 50 50 100 Seepage Pit 100 150 100 Cesspool 150 200 150 Livestock — — These agencies consider that their recommended distances are generally- safe where the upper formations are dry and not more porous than sand, and that these distances should be increased in areas where geologic and other conditions appear to be unfavorable with respect to preventing ground water contamination. Conversely, lesser distances may be safe where favorable subsurface conditions exist, or -vriiere special means of protection, particularly in construction of the ■well, are pro"vided. Results of the well drillers' questionnaires indicate that in actual practice there is considerable variation in distances between possible sources of con-tamination and location of the well drilled. However, : ss;' water' BE arIng^ FORMATION -=-i-r-=-- r M PXfTv lous -Z-1-Z-ZKH3 FORMATIor N=-Z-Z-=-=-Z£f: _. — ^ — — — i;. ' ?...j.-.ij. ! j; i , ii .i', » .i^/'. i| ITW!f W " ^^PERFORATIONS :x:::x:x IMPERVIOUS FORMATION NOT TO SCALE FIGURE 4 THE WELL PROPER ( TYPICAL) -a- lining should not be driven. However, these materials are known to be corrosive resistant and deserve consideration, when it is possible to set the casing in place without driving. Steel casing and line pipe are generally manufactured specifically for that purpose. Manufactured well casing is fabricated in single or double thicknesses. The latter is constructed of two concentric single casings placed together by telescoping one cylindrical section half way along another and stag- gering the joints. Two major casing manufacturers indicate that 12 gage (7/6U inch in thickness) is the minimum size casing they normally fabricate. This minimum thickness applies to both single and double wall casing. Concrete casing is either poured in place or may consist of precast concrete rings. Field investigations by personnel of the Department of Water Resources indicate that casing made of wood is, in general, unsatisfactory. They have observed walls of wood which were leaking and in a state of decay. In reply to the questionnaire sent to all water well drillers in California, 81 percent of the drillers stated that they use steel pipe or rolled steel manufactured specifically for use as water well casing. Some of the drillers use only standard water pipe, and others use several different kinds of casing. The common minimxan thickness of metal casing used by the drillers in the State is about 5/l6 inch. Installation of Casing . Proper installation of casing is a requisite to proper well construction. Damage to casing during placement is to be avoided; it must be made structurally stable and watertight where needed. More care is probably required in placement of casing in a well drilled by the cable tool method than in one drilled by the rotary method, since the hole in the cable tool well is usually smaller than the casing, which necessitates driving the casing, -hS- sometimes with considerable force. Casing or pipe in driven wells is subject to bending or breaking, and the joints may be damaged by the force of repeated blows. Concrete casing, used in relatively shallow, large diameter wells, is subject to cracking and failure due to foundation settlement. Results of the drillers' questionnaires indicate that 94 percent of the drillers extend casing to an impeirvious stratum if feasible. Most common reasons given for seating casing in an impervious stratum are to prevent caving of the materials above and to support the casing. About 45 percent of the dirillers seat casing in cement in the absence of an impervious foundation or when caving formations are encountered. About 25 percent of the drillers reply- ing to a question regarding installation of casing for the entire depth of the well stated that they extend casing to the bottom of all wells. The remainder stated that they extend casing the entire depth only when necessary to prevent caving or to prevent entrance of undesirable water. Casing diameter may be reduced (telescoped) one or more times at successive depth intervals for the following reasons: (1) for purposes of economy; (2) to permit grouting casing in place; (3) to enable the sealing off of undesirable water; and (4) because of inability to drive or sink the larger casing farther. Reduction in diameter of casing is a common practice within the well drilling industry. The United States Public Health Service has recommended that, in telescoping casing of different diameters, the over- lap be at least 8 feet, and that the anniilar space between such casings be filled with not less than 1^ inches of impervious cement grout or with a lead packer to prevent admission of undesirable ground water. Watertight casing is desirable to prevent the entraince of undesir- able water and loose material into the well. Of course, watertightness the full length of the casing is not the object since portions of well casings -46^ are intentionally perforated. What is important, however, is watertightness along the uppermost portion of the casing, at joints, and at depths where it is necessary to exclude undesirable waters yielded by certain strata. Various state and federal agencies and the American Water Works Association are generally in agreement that water well casing should be water- tight to a safe distance below the ground surface. They are not in agreement, however, as to the minimum depth below ground at which water may be drawn into wells, and above which the casing should be completely watertight. To achieve complete exclusion of undesirable waters, these agencies state that metallic casing joints should be threaded or welded so as to be watertight; and vitrified tile pipe, cement-asbestos pipe, galvanized well casing, corrxigated metal pipe, and concrete pipe should be surrounded by not less than six inches of concrete. Results of the well drillers' questionnaires indicate that 60 percent of the drillers use butt welded joints for joining single casing sections, and about 30 percent use collar welded joints. For joining dovible casing sections 47 percent stated they used butt welded joints. Construction of joints noted in many of the dug wells during field surveys made during the course of water resource investigations throughout the State appeared to be unsatisfactory, A number of the dug wells had no casing or had casing constructed of wood, stone or loose brick. Sealing Annular Space . With casing in place the well builder is now faced with the problem of what to do about the space, if any, between the casing and the wall of the hole. If the space is significant in size, a structural problem exists which entails restraining the casing so that it will not be moved or tilted. Of more importance, however, is the elimination of the annular space as a channel for the conveyance of undesirable water. This can be accomplished -47- by sealing the space and by constructing a surface seal at the same time resolving the aforementioned structural problem. The sealing of the annular space in a gravel-packed well is treated in the succeeding section. Determination of an adequate depth or extent of seal is dependent upon several factors, including method of construction and character of fonna- tions encountered above the waterbearing zone, especially the near-surface formation. As previously discussed in this report, authorities in the field of scinitary engineering indicate that bacteria are removed from water by perco- lation through as little as 10 feet of soil or fine sand. However, because bacteria can travel greater distances in more porous formations, and in ortier to insure exclusion of bacteria from wells via the annular space, the space should be sealed a distance below the siorface of the ground of at least several times 10 feet. Various state and federal agencies, counties, and cities having regu- lations, and the American Water Works Association agree that the near surface portion of the annular space between the casing and the wall of a drilled hole should be filled with sealing material. But they do not agree as to the min- imum depth below ground to >Aiich this seal should extend nor to its thickness. According to results of the questionnaire, drillers use a variety of methods and combinations of methods to prevent entrance of surface or shallow subsurface waters into a well. The three most common methods listed were: installation of casing only; sealing annular space with cement grout, clay, or other material; and installation of a surface slab. The pump pedestal, or base, is the foundation structure upon which the pump is set. Depending on conditions, the floor of a pump rocsn, a concrete slab, or a cover over a well can serve as a pedestal. The base is also a means -48- of preventing the flow of surface water into the annular space. The pedestal should be constmcted so that it surrounds the casing and slopes away from it. Concrete is generally specified as suitable material for construction. Gravel -Packed Wells . Although the annular space (assuniing there is one) around the casing of a nongravel -packed well serves no purpose, it does function in the operation of a gravel-packed well and is purposely enlarged for this reason. As stated earlier in this report, the principad reasons for constructing gravel-packed wells are to increase the effective diameter of the well, to prevent fine-grained material from entering the well, to protect the well from caving formations, and to increase the yield of the well by allowing numerous thin aquifers to produce water. In furthering the objectives of gravel-packing, many wells in the State are, and have been, gravel -packed from top to bottom. Thus, the gravel envelope becomes a storage tank for all the water free to gravitate to, or to be drawn into, the well. However, from the standpoint of protection of quality of ground water in and around the well, gravel-packing "all the way" is unsafe. In view of previous discussions in this repoiii of the movement of bacteria and interchsunge of subsurface waters, it should be obvious that such a gravel enve- lope is an excellent conveyance channel for contaminants moving down from the vicinity of the top of the well and for intermingling of waters of various qualities. As stated in the previous section, various agencies are agreed that the near-surface portion of the annular space in wells, with or without gravel envelopes should be filled with a sealing material, but they do not agree upon the thickness or minimum depth of the seal. In answer to the questionnaire sent to drillers, 50 percent stated they sealed the annular space above the gravel envelope in gravel -packed wells. -/f9- During construction of a gravel-packed vrell an access opening (some- times more than one) is provided for addition of gravel to the gravel envelope. As with other openings to the well, they can be protected against the entrance of undesirable water or foreign materials by caps or other sioitable means. Sealing- Off Strata . Where a well penetrates several aquifers and water in a particular aquifer is of such unsatisfactory quality that circu- lation of water from the one strat\im to another is undesirable, the undesirable strata should be sealed off to prevent degradation of quality of waters in other aquifers. To be sidequate, the seal should prevent water from entering the well through the casing or from flowing through the annular space between the casing and the wall of the drilled hole. Remedial measures are best accom- plished during the course of constimctLon of the well. However, the necessity for taking such measures may not be apparent until after the well has been completed and is producing water. Methods and materials used for sealing off strata during construction are described in publications by the United States Public Health Service, ^^°^ the American Water Works Association, '2) the United States Department of the Anny, v32;and E. W, Bennison. (5) j^ general, the methods presented for seal- ing off upper strata often involve placement of impervious material in the annular space between the casing and the walls of the drilled hole from the bottcxn of the zone to be sealed to ground surface. An aquifer containing poor quality water may be overlain by aquifers producing water of good quality. To seal off this intermediate aquifer, enough sealing material must be placed in a selected section of the annular space to prevent movement of the poor quality water into the well or adjacent aquifers. Sealing off waters of vmsatisfactory quality below good quality waters, or "bottom" waters as they are called, entails plugging the bottcm of the well both inside the casing and in the annular space. -50- Of the well drillers that stated they seal off strata containing poor quality water, about one-half use cement grout in nongravel-packed wells and about two-thirds use cement grout in gravel -packed wells. Other drillers use casing and clay or blank casing only. Well Development Well develojanent is essentially the process of removing fine-grained ■aterisLLs from the water-bearing formation adjacent to the perforated interval of the casing. In many areas, proper development is required to obtain the optimum yield with minimum drawdown, to reduce sanding, and to lengthen the economic life of the well. Development consists of some method of loosening the fine material in water-bearing zones, drawing the fines into the well shaft, and removing the fines from the well, A variety of methods can be utilized, including surging of the water in the well. by Jilternately starting and stopping the pump, surging by use of a pliuiger or compressed air, or overpumping, OverdevelojMient or improper development of a well may result in the formation of a cavity in an aquifer due to the removal of too large a volume of fine-grained material. In areas where ground water is confined, an overlying incompetent confining clay layer may collapse as a result of this cavity and allow vertical movement of water from one aquifer to another which, under certain conditions, is to be avoided. Also, careless or hurried development practices may cause collapse of well casing thereby allowing interchange of water between aquifers. Results of the drillers' questionnaire indicate that 62 percent of the drillers develop wells, and that many of these drillers use a variety of methods, the choice of method depending upon conditions prevailing at any -51- particular well. The most ccanmon method is by pumping water fi*om the well at a rate exceeding the expected normal rate of pumping. Introduction of dry ice, swabbing the well, and the use of explosives are also methods used in development of wells in California, Details regarding methods used in developing wells can be found in various publications ^^^' v32;^ Well Disinfection In addition to actual disinfection of water in the well, this feature of well construction includes consideration of the sanitary quality of drilling mud and water added to the well during construction, and of gravel used in gravel-packed wells. Pumping will normally remove contamination introduced during the constmiction or repair of a well; however, the production of safe water can be more quickly obtained by disinfection of the well. In general, procedures used in well disinfection involve the following: pumping the well until clear of turbidity, adding chlorine solution to the well, surging the well to wash the inside of the casing and pipe with chlorinated water, letting the well stand for approximately 2k hours with disinfecting solution in it, and finally pimping the well until there is no color or odor of chlorine in the water. The process should be repeated if necessary. Results of the questionnaire sent to all water well drillers operat- ing in California indicate that 41 percent of the drillers disinfect wells after construction. About 75 percent of these drillers use a Clorox solution, about 17 percent of them use chlorinated lime, and the remainder use other kinds of disinfectants. Gravel used in gravel walled wells should ccane from sources free of sewage contamination, be washed with water of good quality, and handled -52- so that it is free of contamination when installed airound the well casing. Drilling fluid used during the well construction should also be free of sewage contamination. Well Abandonment Although the term "abandoned well" is almost universally used to describe a well that is no longer in use, and is used in this manner in the California Water Code, it is a vague term. It is generally agreed that v^ether or not a well is abandoned depends on the intent of the well's owner, a factor vrfiich plays an important part in the definition of the term. Thus some wells are "temporarily abandoned" or left idle with the pump removed. In this instance, the owner intends to use the well again at some future date. Conversely, in other instances, the owner never intends to use the well again, vinder which circumstances the well should be destroyed. However, a real problem exists in the case where the owner indicates his intent to use again a particular well, and never does, nor does the succeeding owner or heir. Under these circumstances the well is technically abandoned. An idle or "abandoned " well which is left open is recognized as a potential danger to public safety. Such a well also presents a potential danger to the quality of ground water even when properly covered. Open wells provide a channel for the flow of surface water into ground water, and eagy access for small animals and insects (which invariably fall into the well and decompose), as well as other foreign matter. In addition, the casing eventu- ally deteriorates and thereby permits the movement of waters, formerly sepa- rated, from one aquifer to another. Where such interchange of waters must be avoided, the fact that there is no operating pump to remove a poirtion of the -53- toideslratle water niakes the "abandoned" well an even more critical problem. Old wells, in \diich upper waters can actiially be heard falling into the well, have been encountered a number of times in investigations of the department. Consequently, it is of paramoimt importance if the intent of the owner is to use the well again in the future, that it should be kept in a state of good repair. Conversely, if the well is to be destroyed, as eventually every well must, at the end of its useful life, destruction should be accom- pllshea in such a manner that its presence will have no effect on the ground water arotuad it. By "destroyed," it is meant that the well has purposely been filled with material in such a way that the well will not produce water nor act as a conduit for the movement of water. Presumably, if a well is constructed properly to begin with, there would be little need for additional work on the well for an extended period of time, perhaps even to the time when it has been decided that the well is no longer usefvil. The American Water Works Association euid other authorities in the field of water well construction state that proper sealing of "abandoned" wells involves restoring, as far as is feasible, the controlling geologic conditions that existed before the well was constructed. If unconfined grovmd water con- ditions exist, the sealing operations must prevent the vertical movement of surface or shallow subsurface waters to the water table through the original well opening or in the annvilar space outside of the casing. Under confined groTind water conditions, the sealing operations should result in water being confined to the aqiiifer in which it occurs. Each sealing problem should be considered as an individual case. There have been a number of ways devised to accomplish the sealing of wells, some of which, such as the careless filling of the veil with trash -5^- and debris, are almost as detrimental as if the well had been left completely rn. However, there is only one sure way to seeJL a well which is no longer be xjsedj this is to completely fill the well, inclviding probable void spaces, with impervious material. Gravel envelope wells are especially diffictilt to seal adequately, and several authorities recommend that they be filled with cement or driller's mud introduced under pressiire and in sufficient quantity to fill the gravel envelope as well as the interior of the casing. Sixteen municipalities and twelve counties in California have regula- tions and recommendations or policies pertaining to "abandonment" of water wells, About one-half of the municipal, and one-third of the coimty ordinances state that "abandoned" wells shoiild be adequately capped, plugged, or filled so as to prevent personal injviry. The remainder state that pennanently "abandoned" wells should be completely filled with specified material. One-half of these latter municipalities and counties specified cement grout, puddled clay, or similar impejrvious material; whereas the othei^ either did not specify the type of material or specified soil, sand, or gravel. Results of the questionnaire sent to water well drillers in the State indicate that about kO percent of the drillers seal "abandoned" wells. Forty- eight percent of these drillers \ise cement grout as the sealing material, k6 percent use clay or native material, and the remainder \xse some other method such as installation of a metaJ. plate over the opening. Legal Powers and Limitations of the State and Local Agencies With Respect to Ground Water and Water Wells Althovigh there are state laws regarding the licensing of water well drillers, the capping of artesian wells, ana the protection of water quality, there is at present no law which requires tnat specified standards be obser-ved in construction or sealing of water wells generally. A number of cities and -55- coxmties have ordinances regulating water veils. These range in scope from simply requiring a permit to construct a well, to prescrihing detailed standards relating to location, construction, and sealing of water wells. A detailed discvission of existing state legislation is presented in Appendix F to tnis report which, though impuhlished, is available from the Department of Water Resotirces on request. A tabulation of local ordinances peii»ining to construc- tion and atiandonment of water wells is presented in Appendix E. Clearly, the state and local governments have power to enact addi- tional laws and ordinances If necessary to protect groxjnd water basins from pollution and contamination. • 56- CHAPTER V. RECOMMENDED MINIMUM STANDARDS FOR WATER VJELL CONSTRUCTION AND DESTRUCTION OF WELLS In sturmarizing what has been outlined in the preceding chapters, it is apparent that there is considerable variation in present practices, including regulation, in the field of water well construction. Moreover, while there is obvious intent on the part of the well construction industry, advisory groups, and regulatory agencies to prevent impairment to the quality of ground water caused by improperly constructed or "abandoned" wells, there appears to be no broad, uniform approach to the development of the means of prevention. It fol- lows then that the resolution of this dilemma requires the development of minimum standards for water well construction and destruction, which will, if followed, assure the protection of the quality of the State's ground waters as they exist in the ground or as they pass through the well for use. The recommended minimum standards presented in this chapter are intend- ed to be applicable to construction or destruction of wells throughout the State of California. For purposes of these standards, the term "construction" also applies to reconstruction. It is realized that the possibility exists wherein, under particular circumstances, adequate protection of ground water quality may require more stringent standards than are presented here, since not every possi- bility could be considered in the preparation of this report. The need to deviate from general recommendations is, of course, one of the principal reasons that the department is also investigating the development of standards for various sub- areas within the State. As mentioned earlier in this report, additional studies of the need for recommended water well construction standards in certain areas are being, or have been, conducted by the Department of Water Resources. In addition, should these recommendations become adopted as local law, deviations from them would be handled by the enforcing agency as is the case in a number of cities and counties which have ordinances. However, in any event, it is believed -57- that the recommended minimxim standards contained in this report are satisfactory under most conditions as minimums for water well construction and abandonment in all areas of the State. Recommended Minimvun Standards for Water Well Construction For convenience, recommended minirainn standards for water well construe-^ tion have been divided into five categories: (1) well location, (2) sanitary- requirements, (3) casing and annular space, (U) well development, and (5) water quality sampling. In most instances, the recommendations are self-explanatory. However, where some explanation of the statement appears necessary, or where its derivation is unclear, the subject is discussed in more detail. 1. Well Location Because of the many variables involved in determination of the safe distance of a well from potential sources of contamination, no one set of dis- tances will be adequate and reasonable for all conditions. However, because most of the factors involved are usually not known, a set of distances are given which, on the basis of past experience and general knowledge, are safe where dry upper formations, less porous than sand, are encountered. No well shall be located closer than the following distances from the specified sources of contamination. Sewer, watertight septic tank, or pit privy 50 feet Subsurface sewage leaching field 100 feet Cesspool or seepage pit 150 feet In areas where adverse conditions exist, the above distances shall be increased. In addition, if possible, the well shall be located so that it is up the ground water gradient (upstream) from the specified sources of contamination. -58- I I Where possible, wells shall be located on high ground so that the top of the casing is well above any known conditions of flooding, 2. Sanitary Requirements The following recornmendations are primarily concerned with protection of ground water in and around the well, or closely adjacent wells, against con- tamination by surface and shallow, subsurface waters or by entrance of foreign material into the well. A. The annular space between the well casing and the wall of the drilled hole or between the conductor casing and the wall of the drilled hole shall be filled with cement grout or puddled clay between ground surface into an impervious formation overlying the uppermost aquifer. Where such an impervious formation does not exist, thg annular space between the casing and the wall of the drilled hole should be filled with sealing material to sufficient depth to prevent contaminated water from entering the well. In any event, the annular space should be sealed to a depth of at least $0 feet. Depths of the seal should be greater than $0 feet where formations overlying the uppermost aquifer are more porous than soil or fine sand. For diallow wells — 65 feet or less in depth — the annular space shall be sealed three-fourths of the depth of the well from the top, and special precautions shall be taken in locating the well with respect to possible sources of contamination. The thickness of the seal shall be at least one and one-half inches. The sealing material shall be applied, if possible, in one continuous operation from the bottom of the interval to be sealed to the surface. Figure 5 depicts the sealed annular space. Suggested methods for seal- ing the annular space are presented in Appendix G. B. A concrete pedestal, or base, shall be constructed around the top of the well for all wells, irrespective of whether the pump is mounted over the well, •vrtiether it is offset from the casing, or whether the pump is of the -59- MEASURING PIPE GROUND SURFACE MEASURING PIPE WELL WITHOUT GRAVEL PACKING GRAVEL PACKED WELL NOT TO SCALE FIGURE 5 PROPERLY SEALED ANNULAR SPACE -60- submersible type. The top of the pedestal shall rise above ground surface at least six inches and slope away from the casing. C. The opening in the top of the well casing shall be provided with a watertight seal. Where the pump is installed directly over the casing, a water- tight seal can be obtained by sealing the pump base to the pxmp pedestal or well cover, sealing the opening between the casing and the colxann pipe, or setting the pump to secure a watertight seal between the pump base and the rim of the casing. All holes in the pump base which open into the well shall be sealed. Where the pump is offset from the well, where the dimensions of the pump base are smaller than the diameter of the casing, or where a submersible pump is used, the opening between the well casing and any pipes or cables which enter the well shall be closed by a watertight seal. If the pump is not installed immediately upon com- pletion of the well, or if there is a prolonged interruption in construction of the well, a watertight plug or cap shall be provided at the top of the casing. Pump discharge piping shall be located above the ground where possible; and, in the event of a below-ground discharge, there shall be a watertight seal between the discharge pipe and the well casing. D. Access openings into well casings shall be protected against en- trance of surface waters or foreign matter by installation of watertight caps, screens, or downturned "U" bends. E. The use of well pits shall be avoided whenever possible. Well pits shall not be constructed where the pit will extend to a depth below the water table. Where a pit is necessary, the lining shall be constructed of monolithic, reinforced concrete, waterti^t in all respects. The top of the pit shall be covered with a structurally sound, watertight concrete slab or with a house of satisfactory construction. The pit shall be constructed and protected so that rain, flood, or seepage waters cannot enter it. Provision shall be made for automatic drainage of water from the pit. -61- F. Mud and water used in drilling shall be free ftom sewage contamina- tion and come from acceptable sources. G. Gravel used in gravel-packed wells shall come from clean sources and shall be washed before being placed in the vxell. If the source of gravel is questionable, the gravel shall be thoroughly washed and chlorinated before being placed in the well. Gravel purchased from a supplier should be washed at the pit or plant prior to delivery to the well site. H. All wells, except strictly agricultioral wells, shall be disinfected following construction or repair, or when work is done on the pump, before the well is placed in service. The following procedure is satisfactory for dis- infecting a well J however, other methods may be utilized provided it can be dem- onstrated that they will yield comparable results. 1. The proper amount of disinfectant, such that the concentration of chlorine in the well water shall be at least 50 parts per million (ppm) available chlorine, is added to the well. Table 2 lists quantities of various chlorine compounds required to dose 100 feet of water-filled casing at 50 ppm for diameters ranging from 2 to 2k inches. 2. After the disinfectant has been placed in the well, the water pump shall be agitated to thorou^ly mix the disinfectant with the water in the well. 3. The well shall be allowed to stand without pumping for 2ii hours . U. The water shall then be pumped to waste until the odor or taste of chlorine is no longer detectable. -62- TABLE 2 CHLORINE COMPOUND REQUIRED TO DOSE 100 FEET OF WATER-FILLED CASING AT $0 PARTS PER MILLION Chlorine Compounds Diameter of Pipe : or Casing (in inches) (70%) HTH : Perchloron, etc. : (Dry Weight) : (25^) Chloride : of Line (Dry Weight) : (^.25%) Purex Glorox, etc. : (Liquid Measure) 2 lA ounce 1/2 ounce 2 ounces k 1 ounce 2 ounces 9 ounces 6 2 ounces U ounces 20 ounces 8 3 ounces 7 ounces 2 1/8 pints 10 1; ounces 11 ounces 3 1/2 pints 12 6 ounces 1 pound 5 pints 16 10 ounces 1 3A pounds 1 gallon 20 1 pound 3 pounds 1 2/3 gallons 21; 1 1/2 pounds k pounds 2 1/3 gallons NOTE: It is suggested that where wells to be treated are of unknown depth or volume, at least one poimd of 70^ available chlorine or two gallons of household bleach such as Clorox or Purex {^.2^% chlorine) may be added in lieu of the use of the above table. -63- 3« Casing and Annular Space With regard to casing material, its installation, and the disposition of the annular space, it is recommended: A. Casing Material . Well casing shall be of sufficient strength, toughness, and thickness- to resist all forces and stresses imposed during and after installation, and shall be watertight. Damaged or defective material shall not be used. Suggested thicknesses for metal well casings for various depths are presented in Table 3. Concrete casing poured in place shall be adequately rein- forced and watertight. Single layer brick walls shall be surrounded by concrete at least six inches tlxick. Wood shall not be used as casing. B. Installation of Casing . All casing shall be placed with sufficient care to avoid damage to casing sections or joints. The uppermost perforations shall be at least ^0 feet below the ground surface, and preferably below an imper vious stratum wherever possible. For shallow wells — 6^ feet or less in depth - the uppermost perforations shall be at least three-fourths of the depth from the top and special precautions shall be taken in locating the well with respect to possible sources of contamination. All joints in the casing shall be watertight. Where the diameter of the casing is reduced, the annular space between the two casings shall be watertight. C. Gravel-Packed Wells . A conductor pipe shall be placed between the casing and the wall of the drilled hole so as to contain the gravel and to pre- clude the entrance of undesirable water. The annular space between the conductor casing and the wall of the drilled hole shall be sealed to a depth of at least $0 feet with cement grout or puddled clay. A watertight cover shall be installed between the conductor pipe and the well casing at the ground surface. A gravel fill pipe may be installed through the seal but the fill pipe shall be made water tight at the ground surface. The gravel envelope shall not be permitted to -61;- I J 1 TABLE 3 1 SUGCESTED MINmUM THICKNESSES FOR STEEL WATER WELL CASING* 1 Single Casing Depth of Casing In Feet Diameter , in inches ! 6 • i 8 > • : 10 ': • 12 i lU • ': 16 • ': 18 • • : 20 • » : 22 • • « 2U ': 30 0-100 12 12 10 10 8 8 1/U 1/U 1/U 1/U 5/16 X) - 200 12 10 10 8 8 3/16 1/U 1/U 1/U 1/U 5/16 1)0 - 300 10 10 8 8 1/U lA 1/U 1/U 5/16 5/16 5/16 30 - liOO 10 8 8 3/16 1/U 1/U 1/U 5/16 5/16 5/16 3/8 1)0-600 10 8 3/16 1/ii 1/U 5/16 5/16 5/16 5/16 3/8 3/8 X) - 800 3/16 3/16 1/U 1/U 5/1^ . 5/16 3/8 3/8 7/16 7/16 7/16 ror Boo lA 1/U lA ^/16 5/16 3/8 3/8 7/16 7/16 1/2 1/2 • Values in 1 Values in whole numbers are United States standard gage, fractional numbers are thickness, in inches. Double Casing ■ Depth of Diameter, in inches Casing In Feet : 10 • • 12 • *: lU • ': 16 • • • 18 :' 20 • : 22 • • : ; ?u • • 30 0-100 12 12 12 12 10 10 10 10 8 00-200 12 12 12 10 10 10 10 8 8 00 - 300 12 12 10 10 10 10 8 8 8 00 - 1+00 12 12 10 10 10 8 8 8 8 00 - 600 10 10 10 10 8 8 8 8 8 00 - 800 10 10 10 8 8 8 8 8 8 ver 800 10 8 8 8 8 8 8 8 8 -65- connect the waters of two or more aquifers where the quality of water in one or more aquifer is undesirable. D. Seallng-off Strata . Where a well penetrates more than one aquifer, and one or more of the aquifers contain water of unsatisfactory quality, the strata which contain the unsatisfactory water shall be sealed off to prevent en- trance of such water into the well or other aquifer. Sealing material shall consist of cement grout or other suitable impervious material. Sufficient seal- ing material shall be applied to fill the annular space between the casing and the wall of the drilled hole in the interval to be sealed, and to fill the voids which might absorb the sealing material. The sealing material shall be placed from the bottom to the top of the interval to be sealed. Sealing shall be accom- plished by a method which has been approved by the enforcing agency. Suggested methods for sealing-off strata are presented in Appendix G. k' Well Development Developing, redeveloping, or conditioning of a well shall be done with care and by methods which will not cause damage to the well or cause adverse sub- surface conditions that may destroy barriers to the vertical movement of water between aquifers. The latter recommendation is particularly applicable when the quality of water from one of the aquifers is undesirable. Methods used in devel- oping, redeveloping, or conditioning of a well shall be subject to the approval of the enforcing agency. $, V/ater Quality Sampling In order to determine the quality of ground water which will be avail- able from the well and its suitability for intended uses, it is recommended that the water in all wells be sampled immediately following construction and develop- ment, and appropriate analyses based upon intended uses be made. It may also be advisable to take samples of the water during construction. -66- ■ The sample shall be collected after the well has been pumped for a long enough time to remove standing water, and to insure that formation water has entered the well. The water sample shall be collected in a chemically clean con- tainer preferably obtained from the laboratory which has been selected to perform the analysis. The container should be rinsed several times with the water to be sampled prior to collecting the sample. The laboratory performing the analysis should issue instructions regarding the quantity of sample required. However, in general, one -half gallon is sufficient when analysis for heavy metals is not re- quired and one gallon when it is required. Recommended Standards for Destruction of Wells The following recommendations should govern the destruction of wells. 1. For the purpose of definition, a well is considered "abandoned" idien it has not been used for a period of one year, unless the owner declares his intention to use the well again. As evidence of his declaration of intent the owner shall properly maintain the well in such a way that: A. The well has no defects which will facilitate the impairment of quality of water in the well or in the water-bearing formations developed; B. The well is covered with an appropriate locked cap; C. The well is marked so that it can be clearly seen; and D. The area surrounding the well is kept clear of bnish or debris. If the pump has been removed for repair or replacement, the well shall not be considered "abandoned," provided that evidence of repair can be shown. During the repair period, the well shall be adequately covered to prevent injury to people and to prevent the entrance of undesirable water or foreign matter. Wells used in the investigation or management of ground water basins by federal, state, or local agencies or other appropriate engineering research -67- organizations, are not considered "abandoned" so long as they are maintained for this purpose. However, such wells shall be covered with an appropriate locked cap when measurements are not being made. 2. All "abandoned" wells should be destroyed so that they will not produce water or act as a channel for the movement of water. 3. To adequately destroy an "abandoned" well, the hole shall be filled with cement grout or other suitable impervious material from the bottom of the well up. VJhere cement grout is used, it shall be poured in one continuous operation. Prior to filling the hole an investigation shall be made of the con- dition of the well. If there are any obstructions they shall be eliminated by redrilling or cleaning out the hole, ^dhere necessary, to insure that the sealing material fills not only the well casing but also any annular space as well, the casing should be ripped or perforated. For gravel-packed wells, the sealing material shall be applied within the casing, completely filling it, and then forced out under pressure, if necessary, into the gravel envelope. VJater Well Drillers' Report Submission of a report upon completion of a well or of •work on an existing well is required by law (Sections 7076-78 of the California Water Code). These reports can be a source of geologic and hydrologic data, and as such are extremely valuable in studies of the underground reservoirs of the State. Inspec- tion of reports submitted indicates that there is a lack of accuracy, uniformity, and completeness in them, and a need for clarification of the items listed on the report form. Results of the questionnaire sent to water well drillers also indi- cate that there is a demand for such assistance. Therefore, in order to assist the well driller or owner in the preparation of the report, the publication of a guide to its completion appears to be desirable. In addition to a detailed expla- nation of the various items of the Water Well Drillers' Report, such a publication -68- could contain supplementary information regarding the testing and logging of water wells and the sampling of waters in them. Though the "Water Well Drillers' Report form lists "abandonment" as one of the types of work performed, Section 7076 of the Water Code does not specif- ically mention "abandonment" or destruction as a reason for filing a report. In other words, the person who does work in destroying a well files a report only if he chooses to do so. Similarly, work done to repair or reconstruct a well, such as the sealing-off of strata in old wells to prevent interchange of waters of varying qualities, has been overlooked. Therefore, amendment of Section 7076 to include destruction and reconstruction is desirable. -69- CHAPTER VI. SUMMARY Impairment of the quality of grovmd water due to inadequately con- structed or improperly destroyed wells is a significant problem in California. As demands on the State's ground waters increase, the problem will continue to grow in importance, possibly leading to the eventual loss of valuable water supplies. To offset these consequences, the Legislature has directed the Department of Water Resources to formulate recommendations for standards for water well construction and sealing of abandoned wells. In addition to the Department of Water Resources, the State Depart- ment of Public Health has a concurrent interest in the problems caused by defective or improperly destroyed wells with respect to health aspects of public water supplies. Furthermore, water well contractors and local health authorities have expressed the need for statewide standards for well construe- - tion that Include both the protection of the quality of ground water as it occurs in underground formations and consideration of the public health aspects of this problem. This report was prepared in cooperation with the State Department of Public Health as part of a continuing program of the department for discharging its responsibilities vmder the provisions of its authorizing legislation. In order to accomplish the objectives of the investigation, informa- tion relating to various factors which might influence recommendations was compiled and evaluated. These factors are discussed in the succeeding sections. Occurrence and Nature of Ground Water in California In California, ground water occurs xjnder diverse conditions and in a variety of rock types. Most of the readily available ground water occurs in -71- ground water reservoirs composed of young tinconsolidated alluvial materials which underlie valley floor areas distributed throughout the State. Of lesser significance with respect to the production of ground water in the State, but often of local importance, are the sedimentary materials which were deposited in lakes, lagoons or as sand dvines, shallow water marine sediments from which sea water has been flushed, and some types of volcanic rocks. Only theoretically do aquifers and the ground water in them occur clearly as unconfined or confined conditions. Acttoally, in many locations in California, there is much variation from these theoretical conditions. Quality of Ground Water and Its Impairment The qtiality of California's ground water m\ist be maintained at a level suitable for a wide variety of uses, each of which has certain quality requirements peciiLiar to it. There are, however, numerous impairments to that quality, most of which are the outgrowth of continually increasing demands upon the water resources of California and resultant overdraft of groimd water reservoirs. Ground water qxxality problems may be local, confined to the water supplied by a single well, or more extensive as in the case of sea- water intru- sion. There are fo\ir principal ways in which inadequately constructed or improperly destroyed wells facilitate the impairment of grovind water qtiality. These are: by oveirtopping, by interchange of waters, by flow of water down the outside of the casing, and by improper disposal of waste waters. Major sovirces of impairment to the qiiality of ground water are sur- face waters, deep-seated waters, sewage and indtistrial wastes, and sea water. Water Well Construction Standards for water well construction will be ineffective vmless they are capable of execution by the average competent driller vising ordinary -72- i equipment and material. Accordingly, in preparing the recommended standards presented in this report, present water well construction practices, including existing recommendations and regtilations , were considered. Special emphasis was given to public health considerations for the protection of water wells constructed for community domestic water supply. Infonnation regarding ordi- hances pertaining to water wells was obtained from coimties and cities in California. Data and information relative to construction methods and mate- rials presently utilized were obtained from questionnaires sent to all water well drillers. In relation to method of construction, there are five princii)al classi- fications of water wells: drilled, dug, bored, driven, and jetted. Each method has certain advantages and limitations. To prevent the impairment of grotmd water quality by the entrance of foreign material or imdesirable water into well casings, special attention should be given to certain featxares of water well construction. These are: well location, surface features, casing emd einnxilar space, well development, and well disinfection. There is considerable variation in present practice with respect to these feattires. Althoiogh the term "abandoned well" is almost universally used to describe a well that is no longer in use, it is a vague term; and there is general agreement that, in any attempt to define it, the intent of the well's owner must be a recognized part of the definition. An open, vinused well is recognized as a potential danger to public safety. Such a well also presents a potential danger to the quality of grotmd water even when properly covered. Consequently, it is of paramount interest that, if it is the intent of the owner to use the well again in the future, it should be kept in a state of good repair. Conversely, if a well is to be destroyed, as eventually every -73- well must at the end of its useful life, destruction should be accomplished in such a way that its presence will have no effect on the surrounding ground waters. Recommended Minimum Standards for Water Well Construction and Destruction of Wells The standards presented herein are intended to be applicable through- out the State and are to be considered as minimum standards necessary for the protection of ground water quality and for the protection of the quality of water produced by domestic water wells. They are general in nature and are de- signed to permit the well builder to select the method of accomplishment and the material with ^ich it is to be done, within certain limits. Specific standards prescribed include: minimum distances for location of well from sources of contamination, sanitary requirements, casing and sealing (of the an- nular space) requirements, care in well development, and water quality sampling requirements. Except under certain conditions, "abandoned" wells are to be de- stroyed by filling them with cement grout or other suitably impervious material. -7U- APPENDIX A BIBLIOGRAPHY A-1 BIBLIOGRAPHY 1. Ahrens, T. P. "Well Design Criteria. Part 2," Water Well Journal. November 1957. 2. American Water Works Association. "Standard Specifications for Deep Wells." AWWA A-100-58. January 1958. 3. American Water Works Association Journal. "Findings and Recommendations of Underground Waste Disposal." Vol. 45, No. 12, December 1953. 4. Associated Drilling Contractors of the State of California. "Recommended Standards for Preparation of Water Well Construction Specifications," Septonber 17, I960. 5. Bennison, E. W, "Ground V/aters. Its Development, Uses and Conservation," Edward E. Johnson, Inc. First Editicai. 1947. 6. Brantly, J. E. "Rotary Drilling Handbook," Palmer Publications. Fifth Edition. 1952, 7. California State Department of Natural Resources, Division of Mines, "Geologic Map, State of California." 1938, 8. California State Department of Public Health, "Sanitation Guide for Small Water Systems." July 1953, 9. California State Department of Public Health, Bureau of Sanitary Engineering, "Rural Sanitation, Sewage Disposal and Water Supply." Special Bulletin No. 56. June 1931. 10. — — . "Proposed Standards for Public Health Protection of Community Water Supply Wells," January 22, 1959. (Office report.) 11. California State Department of Public Works, Division of Water Resources, "Sea-Water Intrusion into Ground Water Basins Bordering California Coast and Inland Bays," Water Quality Investigations, Report No. 1, December 1950, 12. , "Ground Water Basins in California." Water Quality Investigations, Report No, 3. November 1952, 13. , "Abstract of Laws and Recommendations Concerning Water Well Construction sind Sealing in the United States." Water Quality Investi- gations. Report No. 9, April 1955, 14. . "Recommended Water VJell Construction and Sealing Standards, Mendocino Coimty," Bulletin No. 62. November 1958. 15. California State Department of Water Resources, Division of Resources Planning. "Sea-Water Intrusion in California." Bulletin No. 63. November 1958, A-2 16, . "Water Quality and Water Quality Problems, Ventura County." Bulletin No. 75. February 1959. 17. . "Intrusion of Salt Water Into Ground Water Basins of Southern Alameda County." Bulletin No. 81. December I960. 18. . "Recommended Well Construction and Sealing Standai^is for Protection of Ground Water Quality in West Coast Basin Los Angeles County," Bulletin No. 107 - Draft Report. April 1962. 19. California State Office of Civil Defense, Division of Medical and Health Services. "Sanitation Manual for Disaster Use," March 1953, 20. California State Water Pollution Control Board. "Finsil Report on Field Investigation and Research on Waste-Water Reclamation and Utilization in Relation to Underground Water Pollution." Publi- cation No. 6. 1953. 21. . "Report on the Investigation of Travel of Pollution." Publication No, 11, 1954. 22. California State Water Resources Board. "Water Resources of California," Bulletin No. 1. 1951. 23. Federal Housing Administration. "Minimum Requirements for Individual V/ater-Supply and Sewage-Disposal Systems." December 1951. 2A. Gordon, Raymond W. "Water Well Drilling with Cable Tools." Bucyrus- Erie Company, 1958, 25, Hardenbergh, W. A. "Water Supply and Purification," International Textbook CcMnpany. July 1952, 26, Johnston, "The Vertical Pump," Johnston Pump Company. First Edition, 1954, 27, Stead, Frank M, "A Discussion of Factors Limiting the Bacterial Pollution of Underground Waters by Sewage," Report of the California State Assembly Interim Fact-Finding Committee on Water Pollution. 1949, 28, Stiles, C, W., Cronhurst, H, R,, euid Thomas, G, E. "Experimental Bacterial and Chemical Pollution of Wells via Ground Water and the Factors Involved." Hygienic Laboratory Bulletin No. 147. June 1927. 29, Todd, David K. "Ground Water Hydrology." John Wiley and Sons, Inc. 1959. 30, Tolman, C. F. "Ground Water." McGraw-Hill Book Company, Inc. 1937. 31, United States Department of Agriculture. "Safe Water for the Farm." Farmers '.Bulletin No. 1978. September 1948. A-3 32. United States Departments of the Array and the Air Force. "Wells," Tech- nical Manual TM5-297 and Air Force Manual 85-23. August 1, 1957. 33. United States Department of Health, Education, and V/elfare, Public Health Service. "Ground Water Contamination," proceedings of The 1961 Symposium. Technical Report W61-5. 34. . "Drinking Water Standards," Title 42, Chapter 1, part 72, subpart J of Rules and Regulations listed in the Federal Register. March 6, 1962. 35. United States Department of the Interior, Geologic6il Survey, "Estimated Use of Water in the United States, 1955." By K. A. MacKichan. 1957. 36. United States Public Headth Service. "Sanitation Manual for Ground Water Supplies." Public Health. Vol. 59, No. 5. February 4, 1944. 37. . "Public Health Drinking Water Standards, 1946." United States ^ Public Health Reports. Vol. 61, No, 11. March 15, 1946. 38. Walker, Theodore R. "Ground Water Contamination in the Rocky Mountain Arsenal Area, Denver, Colorado," The Geological Society of America. Bulletin 72, 3 (March I96I) 489-494. A-4 APPENDIX B DEFINITION OF TERMS B-1 APPMUIX B DEFINITION OF TERMS The following terms are defined as used in this report: Abandoned Well— A well whose original purpose and use has been permanently discontinued or which is in such a state of disrepair that its original purpose cannot be reasonably achieved. Active Well — An operating water well. Annular Space — The space between two well casings or a well casing and the drilled hole. Aquifer — A formation or part of a formation which transmits water in sufficient^ quantity to supply pumping wells or springs. Casing — A tubular retaining structure, generally metal or concrete, which is installed in the excavated hole to maintain the well opening. Cement Grout -^ fluid mixture of cement and water of a consistency that can be forced through a pipe and placed as required. Various additives, such as sand, bentonite, and hydrated lime, are included in the mixture to meet certain requirements. For example, sand is added when a considerable vol- vune of grout is needed. Cla£— A predominantly fine-grained material (having a large proportion of grains less than 0.005 mm in diameter) which has very low pemeability and is plastic. Conductor Pipe or Casing;— A tubular retaining structure installed between the drilled hole and the inner casing, generally in the upper portion of a well. Cone of Depression— The water surface in the water-bearing formation within the area of influence of a pumping well. It resembles the shape of a cone with its apex at the pumping level in the well. B-2 Confined Ground Water — A body of ground water overlain by material sufficiently impei^ious to sever free hydraulic connection with overlying ground v/ater except at the intake. Confined ground water moves in conduits under pressxire due to the difference in head between the intake and discharge areas of the confined water body. Connate Water — Water entrapped in the interstices of a sedimentary rock at the time it was deposited. These waters may be fresh, brackish, or saline in character. Because of the dynamic geologic and hydrologic conditions in California this definition has been altered in practice to apply to water in older formations, even though the water in these formations may have been altered in quality since the rock was originally deposited. Contamination — Defined in Section 13005 of the California Water Code: "An im- pairment of the quality of the waters of the State by sewage or industrial waste to a degree which creates an actual hazard to public health through poisoning or through the spread of disease..." Jurisdiction over matters regarding contamination rests with the State Department of Health and local health officers. Degradation — Impairment in the quality of water due to causes other than dis- posal of sewage and industrial waste. Destroyed Well — A well that has been filled or plugged so that it will not pro- duce water nor act as a conduit for the movement of water. Deterioration — An impairment of water quality. Drilled Well — A well for which the hole is generally excavated by mechanical means such as the rotary or cable tool methods. Driller's Mud — A fluid composed of water and clay (either native clay or com- bination with commercial clays) used in the drilling (primarily rotary) B-3 operation to remove cuttings from the hole, to clean and cool the bit, to reduce friction between the drill stem and the sides of the hole, and to plaster the sides of the hole. Such fluids range from relatively clear water to carefully prepared mixtures of special purpose compounds. Free Ground Water— A body of ground water not overlain by impenrious materials, and moving vuider control of the water table slope. Gravel Packed Well — A well in which a gravel envelope is placed in the annular space to increase the effective diameter of the well, and to prevent fine- ^ grained sediments from entering the well. Ground Water — ^That part of the subsurface water which is in the zone of saturation. Ground Water Basin — ^A ground water basin consists of an area underlain by permeable materials which are capable of furnishing a significant water supply; the basin includes both the surface area and the permeable mate- rials beneath it. Impairment — k change in quality of water which makes it less suitable for bene- ficial use. Impermeable — Having a texture that does not permit water to move through it perceptibly under the head differences ordinarily found in subsurface water. Impervious Stratum — ^A formation or part of a formation which, although porous and capable of absorbing water slowly, will not transmit it fast enovi^ to furnish an appreciable supply for wells or springs. Industrial Waste — Defined in Section 13005 of the California Water Code: "any and all liquid or solid water substance, not sewage, from any producing, manufacturing or processing operation of whatever nature," B-A fc Inactive or Standby Well — ^A well not operating but capable of being made an operating well with a minimum of effort. Packer — ^A device placed in a well which plugs or seals the well at a specific point. Perforations — A series of openings in a well casing, made either before or after installation of the casing, to permit the entrance of water into the casing. Permeability — The permeability (or perviousness) of rock is its capacity for transmitting a fluid. Degree of permeability depends upon the size and shape of the pores, the size and shape of their interconnections, sind the extent of the latter. Pollution — Defined in Section 13005 of the Califomia Water Code: "an impair- ment of the quality of the waters of the State by sewage or industrial waste to a degree which does not create an actual hazard to the public health but which does adversely and unreasonably affect such waters for domestic, industrial, agricultural, navigational, recreational, or other beneficial use, or which does adversely and unreasonably affect the ocean waters and bays of the State devoted to public recreation." Regional Water Pollution Control Boards are responsible for prevention and abate- ment of pollution. Pressure Grouting — ^A method of forcing impervious grout into specific portions of a well, such as the annular space, for sealing purposes. Puddled Clay — Clay or a mixture of clay and sand, kneaded or worked when wet to render it impeirvious to water* B-5 Sewage — ^Defined in Section 13005 of the California Water Code: "airy and all waste substance, liquid or solid, associated with human habitation, or vrtiich contains or may be contaminated with hiiman or animal excreta or excrement, offal, or any feculent matter," As used in this report, sew- age is included as part of the waste waters carried by community sewer systems. B-6 APPENDIX C WATER QUALITY CRITERIA C-1 APPENDIX C WATER QUALITY CRITERIA Criteria presented in the following sections can be utilized in evalu- ating mineral quality of vater relative to existing or anticipated beneficial uses. It shoxild be noted that these criteria are merely guides to the appriasal of water quaJJLty. Except for those constituents, which are considered toxic to human beings, these criteria should be considered as suggested limiting values. A water which exceeds one or more of these limiting values need not be eliminated from consideration as a source of supply, but other sources of better quality water should be investigated. Domestic and Municipal Water Supply The following tabulation gives the limiting concentrations of mineral constituents for drinking water, as prescribed by the United States Public Health Service. UNITED STATES PUBLIC HEALTH SERVICE DRINKING WATER STANDARDS 1962 Mandatory limit in ppm 0.05 1.0 0.01 iromium (Cr+6) 1 0.05 0.2 0.05 0.01 0.05 Constituent Arsenic (As) Barium (Ba) Cadmiimi (Cd) Hexavalent ch Cyanide Lead (Pb) Selenium (Se) Silver (Ag) Nonmandatory, but Constituent recommended limit Alkyl benzene svilphonate (detergent) Arsenic (As) Carbon chloroform extract (exotic orgEinic chemicals) Chloride (Cl) Copper (Cu) C-2 0, 0, .5 .01 0, 250 1, .2 .0 UNITED STATES PUBLIC HEALTH SERVICE DRINKING WATER STANDARDS 1962 (continued) Nonmandatory, but Constituent recommended limit Cyanide 0.01 Flvioride (F) I.7 Iron (Fe) 0.3 Mangajiese (Mn) O.O5 Nitrate (NO3) h^ Phenols 0.001 Sulfate (SOi^) 250 Total dissolved solids 5OO Zinc (Zn) 5 In addition, the United States Public Health Service recently announced limits on concentrations of radioactivity in drinking vaters. These limits are as follows: Recommended maximum limits Radionuclide micromicrocuries per liter D -q- 226 Radium 3 Strontium^ 10 Gross beta activity 1,000* *In the known absence of strontium -90 and alpha emitters Interim standards for certain mineral constituents have recently been adopted by the California State Board of Public Health. Based on these standaMs, temporary permits may be issued for drinking water supplies failing to meet the United States Public Health Service Drinking Water Standards, provided the mineral constituents in the following table are not exceeded. UPPER LIMITS OF TOTAL SOLIDS AUD SELECTED MINERALS IN DRINKING WATER AS DELIVERED TO THE CONSUMER Permit Temporary Permit Total solids 500 (lOOO)** I5OO ppm StOfates (SOl^) 250 (500)** 6OO ppm Chlorides (Cl) 25O (500)** 6OO ppm Magnesivm (Mg) 125 (125) I50 ppm **Numbers in parentheses are maximim permissible, to be used only where no other more stiitable waters are available in sufficient quantity for use in the system. C-3 The California State Board of Public Health has defined the maximim safe amounts of fluoride ion in drinking water in relation to mean annual temperature . Mean annual Mean monthly fluoride temperature ion concentration 50°F 1.5 ppm 60OF 1.0 ppm ' ,. 70°F - above 0.7 ppm Even though hardness of water is not included in the above standards, it is of importsmce in domestic and indiostrial uses. Excessive hardness in water] used for domestic purposes causes increased consumption of soap aind formation of scale in pipe and fixttires. The following tabulation for degrees of hardness has been suggested by the United States Geological Survey: Range of hardness , expressed as CaCO ^, Relative in ppm classification 0-60 Soft 61 - 120 Moderately hard 121 - 200 Hard Greater than 200 Usually requires softening Indttstrial Water Supply Water quality criteria for industrial waters are as varied and diversi^ fied as indvistry itself. Food pixjcessing, beverage production, pulp and paper manufacturing, and textile industries have exacting requirements. However, cooluring interruptions of construction before installation of the well pxmip, the well opening shall be closed with a cover welded to the casing to prevent entrance of contamination or debris. Precautions shall also be taken to effectively close the well hole opening temporarily during overnight shutdowns. E. Location of Casing Perforations It is desirable that the uppeimost perforations of the well casing be located below an impervioios strat\m. Where impesrvious strata are non- existent or 50 or more feet from the surface, perforations shall be deep enough to prevent entry of shallow surface waters. In no event shall perforations be closer than 50 feet to the ground stirface. In shallow wells or where perforations ajre not below an impervioiis stratum, special restrictions shall be placed upon location of the well with relation to potential sources of sewage contamination. In this event, the well shall be at least I50 feet from the nearest sewage disposal. C. Dug Wells Dug wells should be avoided, but where used shall have an impervious watertight lining with tight joints extending to a minimum depth of 25 feet below the groxmd surface, sind shall be so located that there D-6 is no vindergroxand sewage disposal vithin 250 feet. Where the method of well construction or the character of the formation is such that a space exists hetween the dug we3JL lining smd the hole after the well is constructed, then this space shall be grouted, or otherwise sealed, to a minimum depth of 25 feet "below the ground surface. An impei^o\as and structvirally sound cover shall he placed over the top of dug wells. Treatment of water farom dug wells may he required to assxire safe quality, D. Gravel Walled Wells 1. Conductor Casing. Where gravel walled wells are constructed, a conductor casing with watertight joints shall extend to a depth of 50 feet. Gravel walled wells shall have a drill hole having a diameter at least six inches larger than the conductor casing. The annular space "between the excavation line and the outside of the conductor casing shall he filled with cement or concrete grout, or other material such as drilling muds having equivalent sealing properties. If the well is located in an area where porous formations are continvious from the surface to a depth greater thein 50 feet, specisil restrictions shall he placed upon location of the well with relation to potential sources of sewage contamination. In this event, there shall he no iinderground sewage disposal within I50 feet of the well. This casing shall he sealed at the ground surface as is described in Section V-A "Sealing of Casing." 2. Gravel. All gravel used in gravel walled wells shall, he soxuid emd shall come from gravel sources free from sewage contamina- tions, shall he washed with a water free from sewage contamination. and shall be so handled that it will not "becxime contaminated before placing in the well, 3. Drillers Mud. Drillers mud and the water iised therewith shall be free from sewage contamination and shall be so handled that it will not become contaminated during constioiction of the weJJL. E. Sealing Outside of Well Casing Where the method of well construction or the character of the for- mation is such that a space exists between the outer casing of the well and the hole after the well is constructed, then this space sha3J. be grouted, or otherwise sealed on edl drilled walls (except gravel wall construction covered in Section IV-D "Gravel Walled Wells," paragraph l) to a depth of 50 feet. V. Otop Construction of Well A. Sealing of Casing The well casing shall extend above ground level and throxigh a pump hovise floor slab or a pump block. The slab or block shall extend at least six inches above the surrounding groimd level. The slab or block shall be impervious and free from cracks. The top of the casing shall be sealed to effectively exclude such materials as wind- blown dvist, small animals and insects, pump drippage, rain, water, etc., as follows: 1. If the well pump is set directly over the casing, the casting of the pump base shall fit tightly on the pimp block or slab. 2. If the pump is offset from the well casing, the annular ring be- tween the well casing and the pump suction pipe shall be closed by a tight seal which can be removed as necessaiy to provide maintenance of the pvmp elements. D-8 3. Where the casing is sealed "by the metal pxnnp base, all holes in the pximp base shall be tightly closed, Adeqtiate means shall be pzovided to lead dripi>age f xx>m packing glands away from the pvmtp base and well casing. B. Access Openings into Well Casing Access openings into the well casing for addition of gravel, for sounding the well, for air release, for lubrication, for disinfection, or for any other purpose necessary for maintenance and operation of the well, are peimited but must terminate above flood water levels. These openings shall be protected against entry of small animals, insects, extraneoxis water, pump drippage, and other contaminating matter, by caps, screens, or downtumed "U** bends, as suitable for the given situation. A Y atvb 1^ inches to 2 inches in diameter shall be welded, with a tight Joint, near the top of the casing, extending above the floor level in the pump hotuse to provide access to the well casing. C. Pump Discharge The pump discharge piping should be located above ground. In the event of a below-ground discharge, there shall be a positive, water- tight seal between the discharge pipe and the well casing, and sixch connedtion shall be easily accessible for inspection. This will require a pit \rtiich wilJL be subject to limitations as noted below. D. Well Pits 1. The use of well pits (and below-ground discharge pipes) should be avoided. In no case shall a well pit be used in areas sub- ject to flooding or where the pit extends to a depth below the D-9 water table. The pit shall be watertight, constructed of mono- lithic, reinforced concrete. The top of such pit shall "be covered, either with a concrete slab or with a hoiise of equiva- lent watertight construction. 2. The casing shall be carried at least six inches above the pit floor. 3. The well pit shall be so constructed and protected that rain or seepage waters cannot enter the pit. The pit shall be provided with a drainage sump and an automatic sump ptimp (or if topog- raphy pennits, a "gravity" discharge). The discharge pipe frcan this sump shall not be connected to any sewer or pipe drain. The outlet of the sump pump discharge pipe shall not be below ground level. It shall be above any possible flooding level and shall be protected against entry of small animals. k. Pits shall have easy access for proper operation, maintenance, and inspection of the eqiiipment, and shall have a locked door or hatch to prevent accidents. Doorways or hatches shall effec- tively keep water o\it of the pit. VI, Pump Blowof f Any blowoff or drain line from the p\anp discharge shall be located that there is no hazard to the safety of the water supply be reason of flood- ing, back siphonage, or back pressvire. There shall be no connection to any sewer. VII. Lubrication Oil and water used for lubrication of the pump and pump bearing shall be of satisfactory bacteriological quality so as not to impair the bacterio- logical quality of water drawn from the well. D-10 VIII, Housing of Well amd Appxirtenances The well and pump shall be housed in a locked structure to provide protection against the elements, to exclude small animals, "birds, and insects, and to protect children or other trespassers from accidents . IX. Sample Tap A sample tap shall be provided on the discharge line so that water, representative of the water in the well, may be drawn for laboi^tory analysis. X. Disinfection New wells shall be disinfected. Notification shall be made to the owner or his agent when the well has been disinfected. D-U APPENDIX E SIMMARY OF WATER WELL CONSTRUCTION AND SEAIING ORDINANCES IN CALIFORNIA £-1 APPENDIX E SUMMARY OF WATER WELL CONSTRUCTION AND SEALING ORDINANCES IN CALiraRNIA Table No . Page E-1 Counties E-3 E-2 Cities E-6 E-2 I O EM +» 4) ^1 4) '3 S .. .. ?! c o . ^ u to +5 O h o^^ CO > M c aJ O +> «J -H U (0 (h c! w 0) (U cd +> o u Q g cd iH *P a H 2 •H 0) o •cj o r-i -H H -P t) eS ts O o H ■P 51 tS 0) ft hO c •rl H >» >. H -P t) 03 c: >H 3 (U -P bO c! aj a •H 0) +> a i h c S Q 'i 1 (U u >> -p X X X X X X X X X I H 0) X X X X JO tH -P +> (U S3 M 0) a o 000000 a s s s s s woo MOOOOWOOOWOOO CO H O W •;;l 4) bO •H T! u ES G 0) <: 2 sa p4 H s ^^ 10 M 0) tt ^ ^^ss ^ 0} cS ea 0) s s s s E-3 8 CQ O O ^% t» a ■^■^ o Id ■p 03 U o o -P a 31 0) P4 ^ ■POM C o aj <0 o i i ■p 5 X X t>< X !x! X X X X X X X X X X X X X X X X 5:3 5 '^'i ■^ a> (u a> w a W too 0000000(0 CO o 0) ^ (0 (0 (0 O O to 5h oa to o o o o o © 0) a s a fe: IS >l ^ a> ^ 0) ^1 «> •H s Bt a^ § y 1 0) > M§ oa 0) M H H a a o PLi IX, 5 a a «^ tf 03 © 03 -H -P O P d *D h^ s 3 3 3 CO CO CO oJ 45 2 ;3 moo p " d (U 0) H fl -H -H O CO CO CO CO E-k H I CO u 0) H 12 f i •H O •p (0 o o 0) (Q H +» O 51 p. c •H 8 +> a s 5 c; I o o M X O +> oooootaooow ?t ^ >> M U crt P f- E 1 ■p •p 1 CQ CQ IH H ^ E-5 0) i a o •H -P' O g§ H +> 4) d o 31 -P hO o i ci o •H •P I 0) O t>< X d o O (U -d •H Ti ft (0 03 •p +> !§ s^ (i (OOtOtOOOOtOOOOOOOOOOO^OOOOOO m pq pQ o o o o o o (3 H » V 0) ^ -p CO S O.H O H tr^ ::ia a d -9 ^ X ><; X X X O O M :9 o (0 o OOOOOOOOOOOW 43 O oJ pq o O W o to w O 2S •H H to W fe P-H CO a (0 6 ? •p 2 B (0 H ■g [^ (I) H (3 j>. 1 H 5:^ w fg <=5 _ o -d to p S3 > •H (U +> H CO W M W J to Xi > ■p ■P •H o O S5 •H O a +» X u X u u V 0) C C! ■p +> o o o o •H o OOMW OOOOOOOW 5 £ O O IQ a &; s a (1) O o m (0 O O O M a a a 0) jO O O O S a js; S 3 V Illlllll H -H CO Pi r-j 3 P -H g 3 J* Jd (U p O H to iu d o fi _ a o o o (i4 &< fl^ ECO p 23 (0 th CM « K « E-8 1 t u o ts to a a CO u ■d (U ■p ■p CI H -P 5 §• H O ^ (U P tl£ o ■p •H O X X X X X >< X ^ J-l -P M p to '^ P»& +> V a» o W o a CO O O (Q X X X X to o o O (0 CO 0) a a a u «> OCOOOOOOOMMOOOOO a (Daaasaaojiuaaaaa O o o (U o s o •xS § -p IS o o •H H >» rH O U 9) -p •H O !x: O O O O O M a a a a s « ■P 0) « >> (0 Td -P •H (U a b ^ J3 EH -P oodl uba 'd' 12 JH 1 y •H -p o K P4 ,Q o E-10 APPENDIX F This appendix is available from the Department of Water Resources on request. F-1 APPENDIX G SUGGESTED METHODS FOR SEALING THE UPPER PORTION OF THE ANNULAR SPACE AND FOR SEALING-OFF STRATA G-1 APPENDIX G SUGGESTED METHODS FOR SEALING THE UPPER PORTION OF THE ANNULAR SPACE AND FOR SEALING-OFF STRATA Following are listed several methods for sealing the upper ix>rtion of the sinntilar space (the "surface" or "ssuoitary seal") and for sealing-off strata containing undesirable water. They are sx;iggested methods only and are not a part of the standards for well construction presented in this report. General 1. No drilling operations or other associated work in the well shoiald be conducted for at least 2k hours, and preferably 72 hours, after sealing operations have been completed. 2. Before installing or reinstalling the pump assembly, the well casing shoiiLd be inspected and cleaned out if necessary. 3. Cement grout used in sealing should consist of one or two parts of sand to one part of cement, and not more thaji six gallons of water per sack of cement. Admixtures should not exceed 10 percent of the volume of cement. Neat cement (cement and water only) is preferred over other grouts, as it eliminates the possibility of separation of sand and cement diiring placement. A good neat cement grout mix will consists of five gallons of water per sack of cement. Sealing the Upper Portion of the Annular Space The following methods can be used to provide a "sanitary" seal of the upper portion of the sjinTilar space. The first method is the method most often used and appears to be the most successful. Grouting Pipe Method . In. this method, a seal is placed in the annular space from the bottom ttp throiagh a grout pipe suspended in the annular space in conjunction with the use of a conductor pipe. G-2 1. Dri3J. the hole large enovigh so that a conductor pipe cam "be installed in the upper portion of the well. 2. Provide a grout retainer in the anniilar space below the interval to be sealed. 3. Ebctend the grouting pipe down the annular space between the casing and the conductor pipe to the bottom of the interval to be seeiled just above the retainer. k. Add grout in one continoxis operation, beginning at the bottom of the interval to be sealed at the same time pulling out the conductor pipe. The grouting pipe should remain sulanerged in the sealing material during the entire time it is being placed. If the annular space is restricted or no conductor pipe is tised, it may be necessary to Jet the grout pipe to the reqiiired depth. Pressure Cap Method . In the pressiire cap method, the grout is placed in the bottom of the hole throtJgh a grout pipe set inside the casing. 1. The casing or other inner pipe is suspended about two feet above the bottom of the drilled hole and filled with water. 2. A pressure cap is placed over the casing and a grout pipe extended thro\igh the cap and casing to the bottom of the hole. 3. The grout is forced through the pipe, up into the annvilar space around the outside of the casing, to the ground s\irface. k. The casing is lowered and sealed into its permanent position after the grout is in place. 5. When the grout has set, the plug formed dviring grouting is removed and drilling of the rest of the well is continued. Dimip Bailer Method . In the dump bailer method, the grouting is done with the hole drilled only slightly below the bottom of the casing and dril- ling is completed after the grout is in place and set. G-3 1. Enough impervious grout is placed in the casing to fill the lower 20 to J4O feet of the hole "by lowering a Taailer filled with grout into the casing and opening the bottom valve which dumps the load of grout at the desired level. 2. The easing is raised 20 to itO feet with the bottom of the casing remaining in the grout. 3. The casing is filled with water and capped, and the water- filled casing is then lowered to the bottom of the hole. This action shoiild force the grout up the annular space between the casing and the drilled hole. The casing must remain capped xmtil the grout is set. If it is anticipated that there will be difficulty in msmeuvering the capped, water- filled casing, water can be put in on top of the grout without lifting the casing. Continue to add water to the casing until a quemtity equal to the volume of grout has been put in. This should force most of the grout out of the lower end of the casing. k. When the grout is set, drill through the hardened cement in the lower end of the casing and continue drilling the well. Seallng-off Strata The following methods can be used in sealing-off strata or zones. The Pressure Grouting Method . This method can be employed where an annular space exists between the well casing and the wall of the drilled hole. 1. Perforate the casing opposite the interval to be sealed. 2. Place a packer, plug, or other sealing device in the casing at or below the bottom of the perforated interval. 3. Place grout In the casing opposite the interval to be sealed by means of a dump bailer or gix)ut pipe. *' k. Place a i)acker or other means of sealing the casing above the perforations . G-k 5« Apply pressure to the packer to force the grout through the perforations into the interval to he sealed. 6. Maintain pressure until the material has set. 7. Drill out the packer and other material remaining in the well. Liner Method . Where an annular space does not exist between the well casing and the wall of the drilled hole, the liner method can he employed. 1. Place a smaller diameter metal liner inside the original casing opposite the perforated interval to be sealed, and extend it at least 10 feet above smd below the perforated interval. 2. Provide a grout retaining seal at the bottom of the sinnular space between the liner and the well casing. 3« Extend the grouting pipe to the top opening between the liner and casing, and fill the anntilar space between the well casing and the liner with grout in one continuous operation. k. The grouting pipe should remain submerged in the sealing material during the entire time it is being placed. G-5 66048 9-62 750 SPO 061 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW RENEWED BOOKS ARE SUBJECT TO IMMEDIATE RECALL MAR 17 1967 957 LIBRARY, UNIVERSITY OF CALIFORNIA, DAVIS Book S]ip-50m-8,'63(D9954s4)458 anfim? California. Dept. of Water Resources. Bulletin. Call Number: TC82U C2 A2 rtn . TUst 306017 California. Dept. TC82Ii C2 of Water Resources. A2 Bulletin. no. 7UA C.2 PHYSICAL SCIENCES UBRARY LIBRARY UNIVERSITY OF CALIFORNIA DAVIS 306017 UNIVERSITY OF QALlFOfjNIA. DAVI! 3 1175 02037 7068 ni