Centennial provides an array of archaeological and historical consulting services, all of which are tailored to assist its clients in meeting the mandates of historic preservation statutes.
The National Environmental Policy Act, or NEPA, declares a “national environmental policy” that requires a multidisciplinary approach to be taken in considering the effects of major projects. Archaeological and historical resources are regarded as elements of the national environment, and as such the effects of undertakings on such resources must be considered as part of the NEPA analysis process. NEPA established the Environmental Impact Statement (EIS) and the Environmental Assessment (EA), commonly referred to as NEPA documents. Cultural resource technical reports are typically produced in support of a NEPA document, with information about threatened sites summarized in Affected Environment and Environmental Consequences sections of the NEPA document.
An intensive inventory represents the first major step of the Section 106 compliance process although it is always preceded by a file search, or “Class I inventory.” The file search examines existing agency databases in an effort to determine if previous field inventories have been conducted in a project area and if sites have been recorded. The intensive inventory, commonly referred to as “Class III,” entails a systematic pedestrian survey of the project area, which is known as the Area of Potential Effect. All prehistoric and historic cultural resources within this area are fully documented, mapped, and photographed, and are then evaluated according to the eligibility criteria of the National Register of Historic Places. A cultural resource technical report detailing the inventory results and presenting evaluations and management recommendations is generated for submittal to the lead federal agency and the appropriate State Historic Preservation office.
Evaluative Test Excavation
Test excavation is an extension of certain intensive Class III inventories. Its sole purpose is to facilitate National Register evaluations, and it is carried out in cases where surface evidence alone is insufficient to permit the site evaluation process to go forward. Testing is not a comprehensive data retrieval exercise, and it is conducted in such a manner that damage to the site is limited. Testing typically consists of excavation of 3-inch diameter auger probes, 1-inch diameter soil probes, formal units measuring 1 meter x 1 meter, or some combination of these approaches. The total area of surface disturbance on a given site will rarely exceed 8 square meters. Information about the subsurface characteristics of the site, including both archaeological content and soil properties, is integrated into the evaluation process. Test excavation results are usually included with the intensive inventory technical report but may also be reported separately.
The preferred alternative in dealing with significant (National Register-eligible) cultural resources is always avoidance, and Centennial works with its clients and agency representatives to find ways to avoid and protect sites wherever possible. In cases where avoidance is not feasible, project impacts to a site are mitigated through development and execution of a data recovery plan. Data recovery most often takes the form of intensive excavation although other actions may also be carried out including instrument mapping, comprehensive surface collection of artifacts, photodocumentation, or some combination thereof. Mitigative excavation typically targets those portions of a site shown through test excavation to have the greatest data potential. Comprehensive data analysis, artifact cataloguing, and technical report writing follow. In most cases an undertaking may proceed following the conclusion of fieldwork, prior to preparation of the technical report.
Archival Research and Historical Documentation
Documentation by historical specialists is required of certain types of sites, particularly standing structures and linear sites such as trails, railroads, and irrigation canals. Depending upon the circumstances, this work may involve large-format photography, obtaining oral histories, recording to the comprehensive standards of the Historic American Buildings Survey/Historic American Engineering Record (HABS/HAER), or Level II documentation (full descriptive and historical narrative, measured drawing, photography). Archival research conducted in conjunction with field documentation may include examination and interpretation of General Land Office (GLO) homestead records, ditch company and state water engineer records, railroad histories, historical museum archives, and trail maps.
National Register Eligibility Assessment
Intensive inventory, test excavation, and some forms of historical archival research all serve to satisfy the basic Section 106 requirement of assessing cultural resources for National Register of Historic Places eligibility. A site will be regarded as significant if it exhibits physical integrity and meets one or more National Register eligibility criteria which include association with historically important persons or events, embodiment of distinctive characteristics of a type, period, or method of construction, or potential to yield information important to prehistory or history. The final criterion – information potential – is loosely defined. In order to bring the evaluation process into focus, information potential is assessed in the context of regional prehistoric and historic databases which often are available only in unpublished form including technical reports of prior investigations and federal and state agency cultural resource files.
Native American Consultation
Consultation with Native American groups is required for many projects under the National Historic Preservation Act. It is technically a government-to-government process conducted between representatives of tribal governments and the designated lead federal agency for a given project. Its purpose is to obtain information about sites, localities, and areas (including designated Traditional Cultural Properties, or TCPs) that are of religious and/or cultural importance to contemporary Native American groups, and that may be threatened by the project. Very often this work is delegated to the cultural resource consultant by the lead federal agency. Centennial’s role may include initiating contacts with tribal groups, providing documentation about sites recorded in the course of intensive field inventories, and facilitating on-site visits with tribal elders.
International archaeological investigations are normally undertaken on behalf of clients seeking funding through international finance institutions such as the World Bank or the U.S. Overseas Private Investment Corporation (OPIC). Archaeological research is conducted in accordance with the Equator Principles, which through the derivative Cultural Heritage Performance Standards require that archaeological properties be documented and evaluated per international standards and in compliance with national heritage laws. Cultural properties are identified and assessed through systematic survey conducted by Centennial in cooperation with technical experts from the host country. The ultimate product is a Social and Environmental Impact Assessment which details field methodology, describes cultural properties in detail with supporting photographic documentation, and presents management recommendations to minimize impacts to significant properties.