Bulletin 74-81 Introduction

Statement of the Problem

Wells themselves do not cause groundwater quality to deteriorate. Rather, it is inadequate construction, or, in the case of wells that no longer serve a useful purpose, their improper destruction, that can result in the deterioration of groundwater quality. Depending on the circumstances, such quality deterioration may affect the water supplying a single well, or if the pollution is substantial, a sizable segment of a groundwater basin.

The impairment of water quality in an individual well, or group of wells, is the most common. Groundwater supplies have been responsible for a sizable portion of the water-borne disease outbreaks reported in the United States. Most of these outbreaks occurred where wells were so poorly constructed that they allowed contaminants to enter the well. Contaminants entering improperly constructed wells are not limited to disease organisms. There is also a growing number of case histories concerning undesirable chemicals, both toxic and nontoxic, that have gained access to groundwater and adversely affected wells a short distance away.

The mechanism of water quality impairment caused by faulty wells affecting large segments of a groundwater basin is not well defined. In most instances, a number of factors have been involved; the wells have served primarily to facilitate the impairment. The most noteworthy examples in California of widespread water quality deterioration are in coastal groundwater basins that have been subjected to seawater intrusion.

Inadequately constructed or improperly "abandoned" wells are not the sole cause of water quality degradation in a California groundwater basin. A small quantity of contaminants entering one well may not have far-reaching effect. However, (1) the construction of thousands of new wells in California each year, (2) the fact that many are becoming more closely spaced, and (3) the growing number of wells being neglected or indiscriminately abandoned indicate that the potential for impairing groundwater quality is growing. Then, when pollutants move along the lines of natural water movement, the effects will be long-lasting and difficult, if not impossible, to correct.

Inadequately constructed or improperly destroyed wells facilitate the impairment of groundwater quality (see Figure 1 and Figure 2) in five principal ways:

1. When the well is located too close to sources of pollution or contamination or downstream from them so that the well can be directly affected by flow from these sources (Figure 1A). Ironically, sometimes the source of pollution is a nearby abandoned well.
2. When the surface portion of the well is constructed without protective features so that contaminated or polluted waters can flow directly into the well through one or more of several possible openings in or under the pump. Usually under these circumstances only the water in or adjacent to the well is affected (Figure 1B and Figure 1C).
3. When the annular space (the space between the outside of the casing and the wall of the hole) lacks an adequate vertical seal and surface water or shallow subsurface water flows into the well along the outside of the casing. (Note that although the annular space may be filled with granular filter material, i.e., the familiar "gravel-pack", no seal exists and undesirable water can move downward or laterally.) This type of defective well is particularly susceptible (Figure 1D) to contamination.
4. When, during well construction (or the destruction of abandoned wells), aquifers that produce poor quality water are ineffectively sealed off, allowing the interchange of water with one or more aquifers and thus significantly impairing the quality of water in those aquifers. The well now provides a physical connection between these aquifers (Figure 2).
5. When the well is used intentionally, accidentally, or carelessly for the disposal of waste allowing direct contamination of the groundwater to occur. Such disposal is prohibited by law except under specially approved circumstances.

Irrespective of the probability of occurrence and which form of deterioration takes place, wells should be constructed or destroyed such that they do not contribute to the impairment of the quality of California's groundwater supplies. Moreover, while the well construction industry, advisory groups, and regulatory agencies want to protect the quality of the State's groundwater supplies as well as assure that wells are adequately constructed, there is no broad, uniform approach for so doing in California. The resolution of this problem requires the development of standards for water well construction and destruction that will ensure the protection of the State's groundwater as they exist in the ground or as they pass through the well for use. Such standards should be capable of execution by the average competent well driller using commercially available equipment and materials, without imposing undue financial burden on the well owner.

Well standards do more than protect the quality of the groundwater resource; they also provide a degree of consumer protection. When standards are established and implemented in an area, well owners have more assurance that their wells will be constructed properly. Proper construction could mean less maintenance with an extended well life. Most well owners do not realize that deficiencies in design and construction (including failure to close-off access to pollutants described above) are likely to result in higher operating and maintenance costs.

A subject touched upon earlier is the safety hazard posed by the unused or "abandoned" well. While safety is not a matter involving the maintenance of groundwater quality, it should be a concern to all those involved with water wells. Any abandoned excavation is a threat to the safety of people, especially children and animals. Further, State law (Section 24400 of the California Health and Safety Code) requires that abandoned excavations be fenced, covered, or filled. Yet, children (and sometimes adults) and livestock do fall into abandoned wells and other excavations.

By properly destroying abandoned wells, we can easily eliminate this safety hazard.

Figure 1. Avenues of Entrance for Pollutants to Wells

Figure 2. Interchange of Water Between Formations via Wells

Developing the Standards

The Department of Water Resources began formulating standards for the construction of water wells and the destruction of abandoned wells shortly after the enactment of Water Code Section 231 in 1949. The Department made a comprehensive survey of existing laws and regulations governing well construction and abandonment in the then 47 other states and in the counties and cities of California. This survey culminated in the publication of "Water Quality Investigations Report No. 9 - Abstracts of Laws and Recommendations Concerning Water Well Construction and Sealing in the United States", April 1955. Although the report is over 25 years old, it remains a useful source of background information. The Department has continued to keep informed of practices in other states, particularly those in which standards have been established, and changes in the status of California county well ordinances.

Concurrently the Department assembled and evaluated information on the development of well standards in California. The information was grouped into three broad categories: (1) groundwater geology and hydrology, (2) Impairment of groundwater quality, and (3) water well construction practices. The latter included suggestions and recommendations on methods and materials from representatives of State and federal agencies, steel companies, casing fabricators, pump manufacturers, water well drilling contractors, and other organizations and individuals concerned with the development and use of groundwater.

This activity culminated in the publication of the standards in their initial draft form, "Recommended Minimum Well Construction and Sealing Standards for Protection of Groundwater Quality State of California", Bulletin 74, Preliminary Edition, July 1962. In March and April 1965, the Department conducted a series of public hearings in conjunction with the Department of Health Services at six cities in the State. Discussion and comments received centered on two areas: (1) the standards recommended, and (2) means of implementation. Most of those concerned felt that the standards, as written, were too general. Accordingly, the Department decided to redraft them.

Following a review of all prior material and comments received during the period 1963 through 1966, the Department published an interim edition of the standards in February 1967. Two public hearings on the interim edition were held in May 1967, and written comments were received as part of the record. These were also joint hearings with the Department of Health Services.

The eight hearings produced correspondence and an extensive file of transcripts containing information, opinions, and suggestions, which would fill several volumes, if published.

In February 1968 the standards were issued in their current form.

For the most part, the standards can be applied anywhere in the State under practically any conditions. The procedures for closing-off the avenues of access, properly locating a well, destroying an abandoned well, etc., in Del Norte County, at the northwest corner of California, are similar to those in western Fresno County. Similarly, sealing-off the water in one or more zones or aquifers, to prevent its migration to other zones or aquifers, may be just as desirable for a well in western Merced County as it is at one on the Oxnard plain of Ventura County although, perhaps, for different reasons. However, in specific areas of the State it has been necessary to define the existing geologic and hydrologic conditions and the circumstances under which these standards should be applied. For example, it is helpful to describe the areal and vertical extent of geologic materials where sealing is needed to prevent the migration of poor quality water.

Thus, the Department maintained a concurrent and subsequent activity consisting of studies and reports describing the application of standards in designated areas of California. And, in addition to Bulletin 74, the Department issued a number of reports containing well standards for those areas (see Table 1).

One other report, Bulletin 74-1, "Cathodic Protection Well Standards: State of California", March 1973 deals with another kind of well. Cathodic protection wells house devices used to alleviate electrolytic corrosion of pipelines, tanks, and similar installations. Such wells may also function as instruments for the deterioration of groundwater quality. For that reason, standards for their construction and destruction have also been issued.

Table 1 Reports Issued Under Water Well Standards Program
(listed by DWR Bulletin number)

Notes for Table 1:

1. Publications issued prior to June 1971 are out-of-print. Copies may be inspected at Department's district offices, county offices administering well ordinances, and local libraries.

2. P.E. - Preliminary Edition; F.E. - Final Edition.

3. Following the enactment of Sections 13800 through 13806 of the Water Code in 1967 supplemental memoranda reports summarizing the material presented in these publications and recommending the establishment of standards in these areas were issued.

4. Unnumbered memorandum report.

The foreword to the 1968 edition stated that:

"Whereas the standards in this report are as final as they can be at the present time, the Department will revise them from time to time. We recognize that, as with other published standards, to be effective and useful they must be revised and updated in light of both changes in practice and degree of success achieved in their application."

Sufficient changes in the field of water well construction and experience with applying the 1968 standards warrant revising them. Foremost among the changes in construction practices are:

1. The development and use of plastic materials for casing in water wells. A subject only alluded to in the 1968 edition, the use of plastic well casing and screen has had phenomenal growth in the United States. So much has the usage increased that a national materials standard has been developed and a manual of installation practices has just been published.
2. The use of the air rotary drilling method for constructing wells in the hard rock areas of the State. Although this method of drilling was in use in 1968, its use has mushroomed since then. The equipment is very effective and very fast. Coupled with the use of plastic well casing, the method has made the construction of a well several hundred feet deep in one day a common event in hard rock areas.
3. Rapid growth in the use of well screens in place of perforated casing in the intake sections of the wells.
4. Increased use of the reverse-circulation method of well drilling for large diameter deep wells in unconsolidated formations. It too is an extremely fast method.

Other factors include:

1. Population growth in the hilly and mountainous rural areas of California, which has resulted in a heavy demand for individual and community water supplies in those areas.
2. The 1976-77 drought, the most severe in a half-century, which caused a heavy demand for new wells, replacement wells, and well deepenings. It also produced an increased awareness of the significance of the State's groundwater resources.
3. The increasing cost of energy for pumping. In terms of well construction and operation, this has meant greater interest in the design of efficient wells and in well maintenance (previously, a much neglected activity).

These as well as other considerations led to the decision to revise the 1968 edition.

This edition is composed of this Introduction, "Standards", and five appendixes.

While there have been a number of modifications and additions to them, the 23 sections of "Standards" are as listed in the 1968 edition. All references to existing laws, standards, and publications have been updated and, where appropriate, additional explanation is provided. Every effort has been made to clarify wording to ensure its understanding. A number of figures illustrating the standards have been included.

Many technical terms concerning groundwater and water well construction are frequently misunderstood or misinterpreted. The term "seal" or "sealing", for example, has several meanings in the jargon of the well driller, geologist, and engineer, depending on what part of the well installation is under discussion. In this report, we have tried to ensure that the technical terms used are understandable.

A list of definitions appears in Appendix A. Certain definitions are made a part of the standards. Appendix B, Appendix C, and Appendix D describe sealing methods, disinfection, and water quality sampling respectively.

Numerous publications relating to the construction of water wells and to the development, use, and protection of groundwaters have been reviewed in preparation of this report. Included is a considerable body of literature on well construction that has been written since 1968. They are listed in Appendix E in alphabetical order by author.

Establishing and Enforcing Standards

Authority for establishing and enforcing standards for construction and destruction of water wells has always rested with the 58 counties and 429 cities in California.

Where public water supplies are concerned, additional requirements may be prescribed by the Department of Health Services. Prior to the release of the 1968 edition of this report, only three counties and a few cities had adopted ordinances regulating the construction of water wells. In 1967, legislation was enacted authorizing the State (through the California Regional Water Quality Control Boards) to require cities and counties to adopt satisfactory ordinances governing well standards in critical areas. If they did not, the State would adopt such ordinances for the cities and counties. (This procedure is outlined in Sections 13800 through 13806 of the Water Code.)

Today, 33 counties have well ordinances establishing standards for the construction of all wells within their boundaries. They are listed in Table 2. Six other counties have adopted ordinances that deal with specific kinds of wells or conditions (as, for example, individual domestic wells only). While this latter group of ordinances provides protection for the users of water from the specified wells in these areas, they do little to protect the quality of the groundwater resource (in contrast with the 33 counties listed in Table 2). Table 3 lists the six counties with ordinances for specific kinds of wells. Thirty-four of the total of 39 county ordinances specify the standards presented in the 1968 edition, with modifications where appropriate (all of which are more stringent than those in the 1968 edition).

Table 2 County Ordinances in California Concerning the Construction and Destruction of Wells (as of December 1981)

Notes for Table 2:

1. Predecessor ordinance numbers 1100 (12/15/55) and 2324 (7/8/75).

2. Separate ordinance for subdivision wells - NS1203.22 (4/21/64).

Table 3 County Ordinances in California with Limited Application to Wells (as of December 1981)

Notes for Table 3:

1. Amended December 1, 1952, and December 23, 1957.

One-third of the 429 cities in California have also adopted well ordinances. Many cities have working arrangements or agreements with county governments, so it is difficult to state the exact number of cities employing well construction standards.

Cities with ordinances are situated in the following counties (number of cities with ordinances in parenthesis):

Design and Performance Guidelines

While the standards presented here are designed to protect the continued utility of the State's groundwater resources, they are only incidentally related to the effective use of these resources. Events of the past decade have emphasized the need for conservation of water and energy. Furthermore, consumers (in this case, well owners) have become more aware of problems resulting from inefficient operation (as reflected in increased energy consumption) and inadequate maintenance.

Accordingly, this section was prepared to provide well owners and drillers with guidelines for measuring performance that will lead to the design and construction of more efficient wells as well as those requiring less maintenance.

Water Well Drillers' Reports

Detailed and comprehensive knowledge of the occurrence and quality of California's groundwater resources is vital to protecting, conserving, and properly developing them. The data obtained during the construction of water wells are primary sources of geologic and hydrologic information. In 1949 the Legislature concluded that such information would be invaluable in the event of underground pollution, and would provide a fund of geologic information regarding the State's groundwater resources. As a result, legislation was passed requiring the filing of a report with the Department. The report is called the Water Well Drillers' Report and its submittal is also a requirement of these standards (see Section 7 "Reports"). Additional information about the report is presented in “Guide to the Preparation of the Water Well Drillers’ Report,” Department of Water Resources, October 1977.

Comments and Public Hearings on Draft Edition

Where a publication is of general interest or its subject is one on which there can be a diversity of opinion, it is the policy of the Department of Water Resources to issue it in preliminary form and solicit comments from interested organizations and individuals and the general public. Since the standards for the construction of wells and the destruction of abandoned wells recommended herein are for application throughout the State, and because they are specified by many counties and cities (in ordinances or regulations), a draft edition was prepared and distributed for comment (April 14, 1981). In addition, four public hearings or meetings (of an informal nature) were held to obtain the views of persons interested in, or concerned with, the construction and use of water wells. These hearings were conducted in cooperation with the Department of Health Services represented by its Sanitary Engineering Section since this report contains provisions which pertain to the public health aspects of water well construction. The hearings were held during June 1981 at Berkeley, Fresno, Redding, and Los Angeles. In response to a number of requests, the comment period was extended to September 1981.

Fifty-five persons representing 33 individuals and organizations attended the four hearings. Five formal (written) statements were presented and 16 persons commented verbally. In addition, written comments were received from 33 other organizations and individuals. Those submitting written comments are listed in Table 5. Copies of the written comments are available for inspection in the Department's file in Sacramento.

Table 5 Organization Submitting Written Comments on Draft of Bulletin 74-81

All comments were carefully reviewed and considered. As might be expected, opinions differed on the applicability of certain standards, guidelines, and procedures. There is, of course, some validity in each point-of-view, which forms the basis for reconsideration. Many comments were incorporated in this final draft. Others were not used for various reasons. Most of the comments dealt mainly with (1) the standards, specifically Sections 1, 8, 9, 10, 11, 12, 13, 21 and 23; (2) the Design and Performance Guidelines section of this Introduction; and (3) Appendixes B, C and D, which deal with methods and procedures.

Bulletin 74-81 Introduction Notes:

1. The uniformity coefficient is a ratio that describes the variation in grain size of granular aquifer material. It is defined as the ratio of the particle size of a material at which 60 percent of the particles are finer and 40 percent are coarser (called D40) to the "effective" grain size (i.e., the particle size of the material at which ten percent of the particles are finer and 90 percent are coarser (D90). The value of the uniformity coefficient for a material of one grain size is unity; for a heterogenous sand it might be 30.

2. Such a device is described in the Journal of the American Water Works Association, Volume 46, No. 2, February 1954.