18. Does the federal agency have to identify or locate every archaeological site for Section 106 review?

No. The ACHP’s regulations do not require the identification of all of the archaeological sites within the area of potential effects (APE). Rather, federal agencies are expected to make a “reasonable and good faith effort” to identify historic properties, including archaeological sites listed or eligible for listing on the National Register in the APE. An agency’s identification effort can be considered reasonable and in good faith when it has appropriately taken into account the factors specified in 36 CFR § 800.4(b)(1) - past planning, research and studies, the magnitude and nature of the undertaking and the degree of federal involvement, the nature and extent of potential effects on historic properties, and the likely nature and location of historic properties within the area of potential effects.

One of the reasons the ACHP’s regulation contains a post-review discovery provision [36 CFR § 800.13] is that the level of effort is reasonable and in good faith, not 100 percent or exhaustive. The costs attendant with work stoppage because of a discovery should be reason enough for a federal agency to put forth a competent professional effort at the identification stage.

19. What is the “reasonable and good faith effort” regulatory standard?

In order to take effects into account as required under Section 106 of the National Historic Preservation Act, a federal agency must first “take the steps necessary to identify historic properties in the area of potential effects” [36 CFR § 800.4(b)]. To do this the federal agency:

…shall make a reasonable and good faith effort to carry out appropriate identification efforts, which may include background research, consultation, oral history interviews, sample field investigation, and field survey. The agency official shall take into account past planning, research and studies, the magnitude and nature of the undertaking and the degree of federal involvement, the nature and extent of potential effects on historic properties, and the likely nature and location of historic properties within the area of potential effects.  The Secretary's Standards and Guidelines for Identification provides guidance on this subject. [36 CFR § 800.4(b)(1), emphasis added].

This section of the ACHP’s regulations establishes the regulatory standard as well as those factors that must be considered in meeting it.  


20. How do federal agencies meet the “reasonable and good faith effort” standard?

While guidance on the scope of archaeological identification issued by SHPOs or other non-federal agencies often is helpful in determining the appropriate level of effort, it does not define the federal standard and must be considered guidance only. The ACHP has developed guidance on meeting the Reasonable and Good Faith Identification Standard.

Ultimately, it is up to the federal agency to thoughtfully consider and weigh the following factors in developing an effective and reasonable approach to the identification of archaeological properties in Section 106 review.  The federal agency official makes a “reasonable and good faith effort” to identify historic properties by designing and implementing an identification plan that addresses the following factors [set out in the regulations at 36 CFR § 800.4(b)(1)]:

  • “past planning, research and studies;”
  • “magnitude and nature of the undertaking;”
  • “the degree of federal involvement;”
  • the “nature and extent of potential effects on historic properties,” and
  • the “likely nature and location of historic properties within the area of potential effects.”


21. How should federal agencies consider the magnitude and nature of the undertaking, and the degree of federal involvement, in determining the appropriate level of effort for identification? 

Undertakings with the potential for extensive ground disturbance generally will require a more involved effort to identify archaeological properties than those with less ground disturbance. For example, the proposed construction of a new multi-story federal complex with underground parking on a vacant city block may require an intensive survey and deep testing in order to identify eligible archaeological sites. On the other hand, construction of a surface parking lot may require investigations into only the top foot of the soil. Likewise, installation of a six-inch water pipe below the frost line with a Ditch Witch should warrant a significantly less intense effort and may not even involve any subsurface testing prior to laying the line, when compared to a large sewer main.

In determining the level of effort for identification, the regulations [36 CFR § 800.4(b)(1)] call for the federal agencies to consider the “degree of federal involvement” in the undertaking. Federal “involvement” as used here means the federal agency’s degree of control or influence over the undertaking. Federal control and influence is highest when a federal agency proposes some ground-disturbing activity on federal land, such as an Army training area expansion.

Federal agencies that grant assistance or issue permits, licenses, or approvals may have a lesser degree of control or involvement over an undertaking. There are several reasons for this:

  • Federal assistance and permitting agencies do not have the same degree of control as a land managing agency since they typically do not own the land.
  • In most cases the applicant for the assistance or permit conducts the work needed for the federal agency to meet its Section 106 responsibilities, not the federal agency.
  • Because these activities take place on non-federal lands (state, tribal, and private), federal agency influence on what the applicant does to help satisfy the Section 106 process is generally limited to conditioning the assistance, permit, or license with stipulations setting what the recipient will do, not necessarily how it will do it.

For example, for a gas pipeline project needing a certificate from the Federal Energy Regulatory Commission, it is reasonable to expect the applicant to apply professional tools, such as current and accepted predictive models, in order to identify eligible archaeological sites. It may not be reasonable, however, to expect the applicant to refine the predictive model by surveying all low and high probability areas.  


22. How should federal agencies consider the nature and extent of potential effects on historic properties in determining the appropriate level of effort for identification? 

A federal agency is not expected to conduct a 100 percent survey of the area of potential effects.  Rather, the identification effort should be conditioned by where effects are likely to occur and the likely impact of these effects on listed or eligible archaeological sites. For example, archaeological identification efforts for a license renewal from the Federal Energy Regulatory Commission likely would not involve the entire area of potential effects (APE). Rather it would be directed to those locations within the APE that are experiencing project related effects associated with operation, usually along the shoreline. Likewise, identification of listed and eligible archaeological sites for a new highway project would be conducted within the APE where direct effects, such as ground disturbance from road construction, are likely. Archaeological testing, however, also should occur within the APE wherever destructive impacts can be reasonably expected to occur later in time, be farther removed in distance or be cumulative. In this example, testing should not be limited to the confines of the new road alignment because experience has demonstrated that highway interchanges tend to attract future development associated with the transportation corridor.  


23. How should federal agencies consider the likely nature and location of historic properties within the area of potential effects in determining appropriate level of effort for identification?

The identification effort is based on what might be found and where it is likely to be located. In other words, the APE is the geographic area where identification occurs, but it doesn’t necessarily follow that the entire APE must be subject to archaeological scrutiny. Generally, the level of effort would be expected to be more intensive if there is potential for the APE to contain an archaeological site of national significance or value to a living community.  


24. How should federal agencies consider past planning, research, and studies in determining the appropriate level of effort for identification?

A review of previous archaeological work done within or in the vicinity of the area of potential effects (APE) is essential in determining the scope of the identification effort. For example, where portions of the APE have been subjected to archaeological survey using methods that conform to current professional standards, it may not be necessary to conduct additional fieldwork on those areas. Conversely, a more intensive effort reasonably would be expected for an APE that has been the subject of little or no previous archaeological study.

Federal agencies should evaluate the reliability and accuracy of any past work because that factor, as well as changing perceptions of significance, may affect what is considered “reasonable.” In conducting such an evaluation agencies should recognize that archaeological work done prior to the 1992 amendments to National Historic Preservation Act may not have benefited from consultation with Indian tribes or Native Hawaiian organizations (NHOs). Accordingly, even though the APE appears to be well studied, any archaeological sites that had been identified previously, both those determined eligible and those found not eligible, may need to be reevaluated in consultation with SHPOs/THPOs, Indian tribes, or NHOs in order to fully appreciate the site’s significance and value.

Review of existing information also assists in determining the types of eligible archaeological sites that might be present and their possible location. The lack of published regional archaeological information does not necessarily mean no eligible archaeological sites are present in the APE. When planning to conduct identification studies it is essential to consult with the SHPO/THPO, Indian tribes, or NHOs that might ascribe traditional religious and cultural significance to listed or eligible archaeological sites in the APE and others knowledgeable about the region and its past before any survey and field testing begins.  


25. With whom should a federal agency consult in determining how to meet the “reasonable and good faith effort” regulatory standard?

In conducting its identification effort, federal agencies are required to consult with the SHPO/THPO to determine the scope of identification efforts, including the initial determination of the undertaking’s area of potential effects, and to seek information from consulting parties and others about historic properties and effects to them. Federal agencies should also gather information from Indian tribes or NHOs to assist in identifying properties of traditional religious and cultural significance to them within the APE that may be eligible for the National Register.

However, federal agencies should be aware that “an Indian tribe or NHO may be reluctant to divulge specific information regarding the location, nature, and activities associated with such sites” [36 CFR § 800.4(a)(4)].  Accordingly, consultation with the SHPO/THPO, Indian tribes, NHOs, and other consulting parties should begin well before the archaeological survey is performed and continue until identification has been completed. This also means, in some cases, consultation with only the SHPO may not be sufficient to develop an appropriate scope of work for the identification and evaluation of archaeological sites. 

Because Indian tribes and NHOs determine what properties are of traditional religious and cultural significance to them, it is particularly important to reach out to Indian tribes and NHOs to determine their level of interest in the undertaking and its potential to affect any such properties before initiating any archaeological field work. Failure to do so could result in the agency taking what may be inappropriate actions, such as the removal of materials from, or insensitive treatment of, historic properties or could result in the agency having to conduct additional or supplementary identification studies later in Section 106 review.  


26. How are disputes about the “reasonable and good faith effort” standard resolved?

Federal agencies should seek the advice, guidance, and assistance of the ACHP in resolving disputes with other consulting parties on its level of effort to identify and evaluate historic properties [36 CFR § 800.2(b)(2)]. Since the ACHP established this standard, its views on what constitutes an appropriate level of effort to identify eligible archaeological sites deserves careful consideration in the Section 106 process. In the end, however, the ACHP’s views are advisory and the federal agency makes the final decision about how much work is enough.  


27. Why is the “area of potential effects” (APE) important in identifying eligible archaeological sites?

The APE is the geographic area(s) within which an undertaking may directly or indirectly cause alterations in the character or use of historic properties, if any such properties exist. The area of potential effects is influenced by the scale and nature of the undertaking and may be different for different kinds of effects caused by the undertaking [36 CFR § 800.16(d)]. Because the APE defines the geographic limits of federal agency responsibility for purposes of Section 106 review, archaeological survey necessary to identify and evaluate historic properties is carried out within its boundaries. Within the APE, however, the level of effort may vary considerably depending on such factors as anticipated effects and prior ground disturbance.  


28. How is the area of potential effects (APE) determined?

The APE is defined by the federal agency, in consultation with the SHPO/THPO, prior to initiating identification efforts. It is therefore a good idea to start out with an APE that is reasonably broad enough to capture the full geographic extent of the undertaking’s effects, and reassess it as more information is gathered.

An effect to a historic property occurs when an undertaking will alter those characteristics of the property that qualify it for the National Register [36 CFR § 800.16(i)]. In developing the APE for an undertaking, consideration must be given to those effects that will occur immediately and directly as well as those that are reasonably foreseeable and may occur later in time, be farther removed in distance or be cumulative, but still result from the undertaking. 

The APE is not static, but should be adjusted as a federal agency further develops the details of the undertaking and learns more about potential historic properties and how they may be affected.  The input of consulting parties is crucial to this informed revision and refinement of the APE throughout Section 106 review.

Most archaeological sites are considered eligible for the National Register principally under Criterion D, because of their potential to yield information “important in prehistory or history.” This important information lies in the site’s artifacts and features and their association (or context). Accordingly, any action that would alter a site’s context would have an effect on its ability to yield information and thus its eligibility for the National Register. The most easily envisioned effect occurs when potential information (the site context) is threatened with destruction; the site or parts of it are bulldozed or plowed away.

Federal agencies, however, should not confuse delineation of the APE with the project’s construction “footprint” since effects to archaeological properties are not restricted solely to direct physical impacts. By consulting with Indian tribes, NHOs, and others, the federal agency can ensure due consideration is given to all aspects of an archaeological site’s National Register significance. This is especially important when the APE may contain archaeological properties of traditional religious and cultural significance to Indian tribes or NHOs, and/or that may be eligible for National Register listing under criteria other than Criterion D. Such properties, for example, could be affected not only through direct physical impact but also from the introduction of visual or atmospheric elements that would alter the property’s setting and feeling.  


29. Should the area of potential effects (APE) also be defined vertically?

Yes. Since an undertaking’s effects are not restricted to the surface, in delineating the APE, a federal agency also should consider the potential for the undertaking’s effects to occur above and below ground. Because the APE is three dimensional, agencies should consider how the undertaking might impact historic properties on the surface, above it, and below it.

In setting the APE’s lower limits, the federal agency should rely on scientific and engineering analyses to define a depth beyond which alteration to any eligible or listed archaeological site, if present, is not reasonably expected to occur. This analysis should demonstrate that any such site, if present, would not be affected by the undertaking through changes in soil compaction or soil chemistry, for example. The challenge is to determine a vertical limit below which a knowledgeable person can reasonably say there will be no effect to the integrity of a site, should one be present. 

The APE for construction of a surface parking lot, for example, might be quite shallow because its limited subsurface disturbance is unlikely to affect deeply buried archaeological properties.  However, construction of an airport runway that is designed to support enormous weight, while still essentially a surface disturbance, could lead to compaction of buried archaeological properties, and thus would warrant testing to a greater depth.

In determining the geographic extent of the APE, the nature of the historic properties that might be present also should be considered to better understand the nature and magnitude of the effects that might apply. For example, a project that would construct over an eligible archaeological site deemed of religious and cultural significance to an Indian tribe may not cause physical damage to the property. However, depending on the property’s significance, the proposed construction might be expected to diminish the property’s integrity through loss of feeling or association. For this reason agencies are encouraged to consult early and be willing to refine the dimensions of the APE as more information is gathered during the course of Section 106 review.  


30. What constitutes a “reasonable and good faith effort” to identify historic properties in accordance with the ACHP’s Policy Statement on Affordable Housing and Historic Preservation?

Principle VIII of the ACHP’s 2006 Policy Statement on Affordable Housing and Historic Preservation [Affordable Housing Policy, 72 FR 7387-7389] states that: “Archaeological investigations should be avoided for affordable housing projects limited to rehabilitation and requiring minimal ground disturbance.”

Neither existing guidance from the Department of Housing and Urban Development [HUD; e.g., Historic Preservation Fact Sheet #6, “When Should I do Archaeological Surveys?”  nor the ACHP’s Affordable Housing Policy Statement provides a definition of what constitutes “minimal ground disturbance;” indeed, it is likely that a simple definition useful for purposes of affordable housing rehabilitation and applicable across the country is not possible. Rather than define the term the focus should properly be shifted to the question of whether or not an archaeological investigation is needed in order to meet the “reasonable and good faith” regulatory standard for the identification of historic properties established by the ACHP’s regulations.

In determining whether an archaeological survey is necessary, the ACHP’s regulations set forth several factors that should be considered in meeting the “reasonable and good faith” test [36 CFR § 800.4(b)(1)]. Most importantly for purposes of affordable housing rehabilitation, these include consideration of the “magnitude and nature of the undertaking” and “the nature and extent of potential effects on historic properties.”

Consider the magnitude and nature of the undertaking: The ACHP’s policy pertains solely to rehabilitation of existing building stock, not new construction, demolition, or redevelopment. Therefore, most work is limited to bringing existing housing stock up to local code standards. In doing this work, rehabilitation might take place on the interior and exterior of the building, as well as on utility connections between the building and the street.

Examples of common rehabilitation activities that can cause ground disturbance include, but is in no way limited to, foundation repair, installation of exterior foundation drainage, upgrading of existing utility lines, and the delivery and staging of materials to the housing site. Given the nature of the undertaking, ground disturbance associated with affordable housing rehabilitation activities typically is limited in scope and predictable. Accordingly, the broader the scope and more intense the previous construction activities, the less likely are new construction activities to affect historic properties.

Consider the nature and extent of potential effects to historic properties: Typically, utility trenches for affordable housing projects, especially in urban contexts, traverse small front yards from the building directly to the street. Most front yards already have been disturbed from previous construction and the installation of infrastructure. Accordingly, the placement of new utility lines in existing trenches should result in minimal or no new ground disturbance, and absent special circumstances, it would be appropriate to conclude that a reasonable and good faith identification effort does not require any archaeological testing. Similarly, repair of building foundations usually takes place in areas disturbed during the original construction of the building. When such rehabilitation activities are confined to such previously disturbed areas, identification efforts should not require any archaeological testing.

When new utility lines are to be installed in new trenches it still may be appropriate some times to conclude that no archaeological testing is necessary to meet the reasonable and good faith identification standard. Again, the agency official, working with the housing sponsor, needs to take into account several factors. One is the scope and degree of disturbance experienced when the target building was constructed and its infrastructure installed, as most front yards would have already been disturbed by these activities. This factor should not be considered alone, but must be weighed against the size and depth of the new trench. As the width and depth of a new trench increases so does the scope of the ground disturbance.

Because there is always the potential for National Register-eligible archaeological sites to be adversely affected in housing rehabilitation involving ground disturbance, the housing agency official and housing sponsor should work with the SHPO when negotiating Memoranda of Agreements (MOAs) to develop a plan for post-review discoveries in accordance with the ACHP’s regulations [36 CFR § 800.13].

Delivery methods and staging areas also have the potential to affect historic properties, but the scope of these activities also can be minimized. Delivery may vary from dumping construction material to the use of a forklift for unloading. Materials may be staged in yards or adjacent lots, but also can be placed on existing driveways or roadways. Proper equipment used under the right surface conditions sized appropriately for the job helps to reduce ground disturbance, making it reasonable to conclude that archaeological testing is not warranted.

Affordable housing officials and project sponsors should consider ways to minimize ground disturbance with those who will be carrying out the rehabilitation projects. Exercising caution and common sense, in conjunction with adopting measures that limit ground disturbing activities, can minimize ground disturbance and support the position that a reasonable and good faith identification effort does not need to include archaeological testing.