U.S. Department of the Interior, National Park Service, Briefing Statement
|DATE:||January 12, 2006|
INDEPENDENCE NATIONAL HISTORICAL PARK
|PROJECT/ISSUE:||Archeology at the President's House Site|
|AUTHOR:||Jed Levin, Archeologist, Northeast Region Archeology Program, National Park Service|
|BACKGROUND:||This paper discusses the type of archeology to be performed at the President's House site in connection with the development of the commemoration there. The National Park Service recognizes two types of archeological investigations: archeological studies required to comply with Federal regulations, and studies not expressly required by legislative mandate, but designed to address significant research questions. This document addresses both types of archeological studies in the context of the proposed commemoration of the President's House.|
[For further information, please contact Jim Lowe, Capital Program Office, City of Philadelphia, 1515 Arch St., 11th Floor, Philadelphia, PA 19102-1677, 215-683-4422.]
Based on a review of previous archeology conducted on portions of the President's House Site and adjacent areas, and on review of the historical documentation available for the site, the NPS concludes that research excavations on the site hold a low to moderate potential of recovering artifacts and information relating to the period of presidential occupancy. Further, it is likely that if such information is recovered from the site it will bear on day-to-day life in the household as a whole rather than providing detailed information on specific individuals or groups.
The option to conduct research excavations at the site is discretionary. Even if the city elects not to conduct research excavations a review of the potential impact the project might have on historic and archeological properties will be required in order to comply with the requirements of the National Historic Preservation Act (NHPA) and with the National Environmental Policy Act (NEPA). This review will have to be complete before construction can begin and will determine the extent of any required archeology.
The actual cost and duration of a research excavation on the site will depend on the extent of the area selected for excavation, as well as the engineering requirements necessary to render the area safe for excavation and the number of artifacts recovered. An engineering study will be needed in order to develop an excavation plan and to help refine cost estimates. If the limited study area recommended by the NPS is adopted, research excavations would likely cost between $400,000 and $800,000. These excavations would require between six and eight weeks to complete. An expanded study area would require additional time and would increase project costs.
If research excavations are not done, NHPA and NEPA compliance related archeological costs could be as low as $30,000-$50,000. Archeological costs could be kept to this level if a design is developed, following archeological guidance, which entirely avoids impacts that might adversely effect archeological resources. In addition, this approach would mean that there would be no need to build time into the project schedule to accommodate pre-construction archeological excavations.
If a strategy of avoidance of archeological resources is not feasible, then archeological costs are likely to range from $250,000 to $350,000, or possibly higher. Completion of this level of archeological work would require approximately four to six weeks of access to the site prior to construction.
The proposed commemorative installation on the site of the President's House involves significant Federal participation. This Federal component triggers a requirement for compliance with Section 106 of the National Historic Preservation Act and with the National Environmental Policy Act. An important aspect of Section 106 compliance is the review of any Federal undertaking that has the potential to affect below-ground historic resources. Both the cited legislation and the Secretary of the Interior's Standards and Guidelines for Archeology and Historic Preservation detail the procedures for meeting obligations imposed by this Federal regulation. If a site containing significant historical resources is subject to disturbance as a result of a construction project, then the integrity of that site must be considered as compromised. Such action is considered to be adverse and appropriate mitigation is required. Mitigation of disturbance to an archeological site typically involves excavation of the site and the cataloging, analysis, and curation of all recovered artifacts. Mitigation of a site is not complete until all laboratory work is done and a detailed report on the project has been prepared.
Prior to the construction of the Liberty Bell Center (LBC) and associated site improvements the NPS completed historical background studies of the area potentially affected by this construction. These studies covered an area including the President's House site. In addition, archeological excavations were completed for the area where the LBC now stands. These excavations covered a portion of the President's House site.
This previous research provides information on what archeological resources are likely to be present within the area planned for the commemoration and at what depth they are likely to be encountered.
In order to discharge our joint responsibilities under Section 106, NPS would work with a qualified resource management firm retained by the City to follow our standard practice of attempting to design new construction so as to avoid, where possible, impacts on known or suspected archeological features or deposits. That is, the firm would work with the commemoration designer to avoid deep ground penetrations in areas where resources are believed to exist. In areas where this practice is not feasible archeological excavations would be required to mitigate unavoidable site disturbances. Archeological review, and any required mitigation, would follow the Secretary's Standards (cited above) and would be guided by the terms of the Programmatic Agreement that the interested parties (NPS, FHWA, PENNDOT, the City, and the State Historic Preservation Officer) are developing.
Based on past research, we know that there is at least 4-5 feet of fill covering the President's House site. If adequate guidance is provided to the design team we are confident that a plan for the commemoration can be developed that does not require excavation below this depth. This could greatly reduce potential archeological costs and eliminate altogether the need for archeological mitigation.
If this approach proves feasible and a design is developed which entirely avoids impacts that might adversely effect archeological resources, archeological costs will be limited to those necessary to provide archeological guidance to the design team, and, possibly, to provide precautionary archeological monitoring during construction. These costs would likely total no more than approximately $30,000-$50,000. In addition, this approach would mean that there would be no need to build time into the project schedule to accommodate pre-construction archeological excavations.
If a strategy of avoidance proves impossible or undesirable archeological compliance costs would be considerably higher. In this eventuality the cost of archeological testing and mitigation to address construction related archeological impacts would likely range between $250,000-$350,000. Completion of this level of archeological work would require approximately four to six weeks of access to the site prior to construction.
Lacking a specific design from which we can gauge potential archeological impacts this estimate remains imprecise. Depending on the actual design, and the extent to which it threatens potentially significant archeological resources, costs could be significantly higher and the time needed to complete pre-construction archeological excavations could also increase.
Independent of any compliance related archeology which might be required, careful consideration should be given to the possibility of conducting research oriented archeological study of the President's House site. Archeology can broaden and deepen our understanding of the past. Under favorable circumstances it can fill in gaps that result from an incomplete historic record. Archeology is sometimes the only means of filling gaps that result from longstanding neglect in the gathering and curation of historic records, or from historic biases that operated to select some things as suitable for inclusion in the historic record while excluding others.
The NPS conducts research excavations considerably less frequently than compliance based excavations. Compliance archeology is always required if archeological resource are threatened by imminent construction, otherwise important information might be lost to bulldozers and earthmoving equipment. Research projects, on the other hand, must be carefully considered because they involve the excavation of sites that would otherwise be preserved. When an archeological site is excavated it is essentially destroyed as the soil layers are striped and historical features dismantled and when artifacts are removed from their contexts. Recognizing this, there must be a compelling reason to conduct an archeological excavation a site that would otherwise be preserved.
Research excavations are justified if the excavations are conducted within the framework of a research design that is of compelling interest to scholars and the public and is likely to provide information which can advance our understanding of the past. The President's House site is unquestionably of historical importance. Equally certain is the demonstrated interest that the site's history holds for the public and scholarly researchers. If archeology offers significant potential to deepen our knowledge of the site, then research excavations of the site would be justified. Below, we turn to a consideration of the archeological resources that are likely to be preserved under the President's House site, and the potential they may have for addressing important research questions.
The discussion that follows is informed by the extensive historical research on the site that has been conducted by the NPS and the detailed research amassed by independent scholar Edward Lawler. Important additional information is drawn from the archeological background research and excavations conducted prior to construction of the Liberty Bell Center for the NPS by John Milner Associates (JMA).
Three major classes of archeological resources may be preserved within the area of the President's House site. We will discuss each resource class in turn, proceeding from those resources that are least likely to be preserved, to those that are most likely to have survived the ravages of time. In each case we will also assess the potential that the resource has for advancing research on the President's House period. A summary table of these findings follows the text.
The term "historic ground surfaces" refers to the actual preserved surfaces on which people in the past carried out their daily activities. These areas primarily include exterior areas such as yards, walkways, and gardens, but can also include interior floor areas.
Preserved historic ground surfaces provide archeologists with the opportunity to study how space was used in the past. These resources can inform us about the environment in which people lived and worked and how they altered that environment to suite their needs and desires. The persistence of original surfaces can, for instance, show how the landscape was altered to conform to contemporary tastes and utilitarian needs. Historic ground surfaces can reveal the location of former garden areas and paved paths and walks. We can potentially also learn about areas where people worked and identify portions of a site that were reserved for special functions.
Unfortunately, Historical research and archeological evidence suggests that there is virtually no likelihood that any ground surfaces dating to the President's House period have survived later developments on the site.
The documentary background research conducted for the NPS by JMA during planning for the construction of the Liberty Bell Center suggests that several small areas, totaling about 240 square feet, may have survived nineteenth and twentieth century construction activities. While excavation for the basements of later buildings appears not to have occurred in these limited areas, demolition in 1951 in preparation for the construction of Independence Mall included the excavation of the entire block to a depth of at least four feet below street grade. These excavations would have almost certainly destroyed the last surviving President's House era ground surfaces. Archeological work conducted in preparation for the LBC confirmed that that the demolition for the new Mall stripped all the eighteenth century ground surfaces within that project area.
While historic ground surfaces can be a very valuable resource for the study of the past, there appears to be virtually no likelihood that resources of this class exist for the President's House period. Therefore, the research value of this class of resource is judged very low to nil.
This class of resource includes primarily the below-ground portions of building foundations and basement areas. These might include masonry building supports and basement floors.
Structural remains can provide information on the location, size, and shape of buildings. This information can be critically important when it is otherwise absent in the historical record. Structural remains can also reveal information on the material and techniques used in the construction of buildings and provide clues as to how structures were altered over time.
Research recently published by Edward Lawler indicates that it is highly likely that portions of the foundations of the President's House remain preserved beneath the Market Street sidewalk and in the grassy area running thirty-five feet to the south of the south edge of the sidewalk. The main house was a substantial masonry building with a basement and, as such, would have required a robust and deep foundation. These are precisely the kind of structural remains that would be likely to survive the demolishing of the President's House and the later construction on the site. And, indeed, David Howell Morgan, while working for the Works Progress Administration (WPA), recorded structural remains believed to be associated with the building. Later, in 1952, he returned to the site and mapped the foundation remains that appeared to be those of the President's House.
Today, it is not possible to determine with certainty how much of these foundations still exist. While it is very likely that at least portions of what Morgan observed remain preserved below ground, other portions of the foundations may have been destroyed during the construction of a public toilet in 1954. Additional damage may also have occurred during landscaping and utility work associated with the development of the Mall and during the expansion of the toilet in 1984.
In any case, the truncated and fragmentary foundation remains of the President's House are unlikely be of significant research value. In the light of available historical documentation concerning the house, and Morgan's notes concerning the remains he observed, excavation and additional study of the foundations would not materially advance our knowledge of the site.
Notwithstanding the low research value of these remains, they do represent a tangible link with the past. Following NPS policy they will be protected and preserved in the ground. Design plans for the current commemorative installation, as well as any future construction activities on the site, will be reviewed to ensure that no unnecessary damage is done to possible remains of the President's House.
Unlike the main house, aside from possible exception of the bath house (discussed below), there is no evidence that any foundations or structural remains of the back buildings and additions survived the nineteenth and twentieth century development of the site. These structures would not have had basements or been of such a size as to require the kind of deep foundations that the main house had. Their shallow foundations would have been destroyed during later alterations to the site.
Excavations conducted by JMA in 2000 and 2001 for the NPS within the site of the Liberty Bell Center extended into the south end of the President's House site. These excavations took in the area where the brick stable and ice house stood and documented the existence of the basement floors of buildings constructed in the nineteenth century. The floors of these later basements were at a depth that would have been approximately nine feet below the historic ground surface. Construction of these basements would have destroyed the floors and foundations of the earlier out buildings dating to the President's House period.
Historic documentation suggests that the later buildings that replaced substantially all of the back buildings on the President's House lot would have had basements similar to those found during the JMA excavations. Construction of these basements, and the later demolition associated with the construction of the Mall, are likely to have destroyed all traces of the structural remains of the site's back buildings.
The extension that contained the bath house remains a possible exception to this pattern. Edward Lawler has uncovered historical documents which he reads as possible evidence that this extension might have had a basement. The evidence on this point is inconclusive, but the possibility that the bath house had a basement can not be ruled out.
If the bath house did have a basement (and if remains of the basement and associated foundations have survived) their excavation and study could provide precise evidence on the size, location, and orientation of this building. Such a result would be a valuable supplement to the meager historical record and would help confirm aspects of the site's layout.
In summary, for this class of resources, structural remains of the main house are highly likely to have survived, but the research potential for these remains are low. On the other hand, the research value of the foundations and structural remains of the back buildings and extensions is very high, but, with the possible exception of the bath house, the likelihood of their survival is very low.
Shaft features are historic pits generally lined with brick or stone. They were used for a variety of purposes, but the most commonly encountered shaft features are privy pits (outhouses) and wells. Other less commonly found shaft features include ice pits, cisterns, dry wells and other specialized structures.
Shaft features often served a secondary function as receptacles for disposal of trash from adjacent homes and businesses. They may contain household items that were deposited while the feature was in use or after it was abandoned. The upper portions of deep shafts often contain material, primarily soil and furnace ash, intentionally deposited to fill the shaft for safety reasons after it was abandoned.
Archeologists study the placement and physical construction of shaft features to learn about sanitary practices and about how people in the past arranged and used space. When deposits of household trash are found within these features, the study of this material can reveal in great detail aspects of daily life (including behavior, beliefs and cultural patterns) that are otherwise underrepresented or absent in historical documents. Such deposits can illuminate the lives of all strata of society; they are particularly useful in the case of individuals or groups who have been systematically excluded from historical records.
The archeological excavations for the LBC included excavation of the south end of the President's House site. Two shaft features were uncovered in that area. One, the lower nine feet of an ice pit, was built when Robert Morris owned the property and is believed to have been in use later, during the President's House period. The other shaft feature uncovered during these excavations was probably a well. Analysis of artifacts recovered from the upper four feet of this truncated shaft suggests that it was filled during the early twentieth century, and that it is probably not associated with the President's House period.
Research conducted by the WPA and other documentary evidence suggests that three other wells existed on the site. The lower portions of these features may remain preserved on the site. However, based on available documentary evidence, only one of these wells is likely to been constructed and used during the President's House period. One or more additional undocumented wells dating to various periods, including possibly the President's House period, may also exist on the site.
If one or more wells dating to the President's House period are, as appears likely, preserved on the site, they would have moderate research potential. These features are unlikely to contain significant deposits of household refuse dating to the President's House period. Typically, in eighteenth century Philadelphia wells would have been capped and water drawn from them through use of a pump. This would have made it difficult to use an active well shaft as a receptacle for trash deposit, a use that would have been discouraged, in any case, because it would potentially lead to the contamination of the supply of drinking water. Similarly, given the very public nature of the site it seems unlikely that an abandoned well would have been left open to receive trash during the President's House period. Neither George Washington nor John Adams was likely to have permitted such a use on the site of the executive mansion.
Even though well shafts are unlikely to contain domestic trash deposits that would shed light on the President's House period, preserved shafts, if they could be dated to that period, would serve to locate these features on the President's House landscape plan. This, in turn, would help us better understand how the lot was arranged and used.
The WPA identified one feature in the basement of a building constructed on the site in the nineteenth century which they identified as an old privy. If their identification of this feature is correct, this would represent the only privy pit currently known to exist on the President's House site. Base on archeological experience gained at comparably sized sites in the vicinity, it is likely that a total of between four and ten privy shafts are located within the confines of the site. These shafts would date to various periods in the site's history, including the periods before and after the Washington's and Adam's residency. In most cases privy shafts encountered on archeological sites must be fully excavated and their contents studied before it is possible to precisely determine the dates when they might have been constructed and used.
Based on likely patterns of use, between one and four of the privy shafts that might be encountered on the site are likely to date to the President's House period. As was the case with well shafts, discussed above, the identification of privies dating to the President's House period would, even if they contained no significant refuse deposits, reveal information absent from the documentary record on the physical arrangement of the property.
Privy shafts are considerably more likely to contain refuse deposits than are wells. Privy shafts were, by definition, open during their period of use and are therefore more likely to have been used for trash disposal. In contrast to wells, the issue of contamination would obviously not apply in the case of features designed to receive waste. On the other hand, privies were often cleaned out at multiple intervals during their active period of use. Considering the one to four privies likely to date to the President's House period, the probability appears low that any of these would have escaped episodes of cleaning and would, therefore, contain significant deposits of household material dating to the target period.
However, if privy deposits dating to the President's House period are present on the site they would represent a significant research potential. Analysis of such material is likely to reveal much about day-to-day life at the site. Generally archeological studies of privy deposits from eighteenth century urban contexts provide a broad overview of the inhabitants of a household. Rarely do these studies allow us to look at a particular individual in any detail. Items carrying the name or other unique identifier of an individual are exceedingly rare.
It is more often possible to recognize items used by discrete social groups such as women or children. Similarly, it sometimes possible to identify people who share a unique cultural identity through the recovery of items associated with a particular set of beliefs or traditions. People of African decent, for example, may, following long held traditions, have chosen particularly meaningful objects that they used as items of personal adornment. Items of this nature are sometimes found on archeological sites.
The above examples notwithstanding, typically material recovered from common trash deposits can not be confidently linked to individuals or particular groups who lived and worked together on a site. Instead, they tell us about the inhabitants of the site considered as a group.
In summary, shaft features dating to the President's House period have a high probability of being preserved on the site. Viewed more specifically, wells dating to the target period are very likely to exist on the site, but they are unlikely to contain significant artifact deposits dating to the President's House period. Therefore wells can be considered to have a high probability of occurrence but only a low to moderate research potential. Privies also have a high probability of occurrence and are more likely to contain significant artifact deposits dating to the President's House period. Given the common pattern of cleaning out privy pits, the likelihood of finding such deposits is still not particularly high. Privies can be considered to have a high probability of occurrence and a moderate research potential.
The President's House site is situated within a congested and heavily used urban environment. Excavation of the site would involve significant logistics challenges and would require the implementation of a research design that maximizes the research potential of the site while minimizing cost and disruption. The salient research and logistical considerations are addressed below.
Archeological study of previously unexcavated portions of the President's House site would require very deep excavations. On average these excavations would have to extend to at least about ten feet below current grade. Excavation of any shaft features encountered would require additional excavation in and around these features to a depth of twenty-five feet or more below current grade.
An extensive system of shoring would be required in order to provide safe working conditions and to protect surrounding infrastructure. Given the limited space available and the public nature of the site, all the excavated overburden and fill would have to be trucked off-site. Continuous access for heavy equipment during excavation and site restoration would have to be maintained, probably from Sixth Street. Existing utility lines (including the park's data highway and the chilled water line) which cross the work area would require temporary relocation or protection and support throughout the duration of the project. A safe access route for visitors to the LBC would have to be maintained.
Restoration of the site would require filling of the excavated areas and cosmetic landscaping to leave the site presentable until construction begins. The specific requirement for fill material to be use in the restoration, and any necessary compaction, would depend on the engineering requirements for the pending construction.
An engineering survey would be necessary to determining an appropriate shoring system. The engineering study will also provide critical guidance on how close excavations can approach the LBC building and its exterior piers without damage to the building or undue danger to staff and park visitors.
The President's House site has attracted significant public attention. An ongoing program of public education should accompany the excavation of the site in order to address this high level of interest. At a minimum this program should include viewing platforms around the site, frequent bulletins about the work in progress, and possibly interaction with archeologists at work. Such a program will serve to educate about the President's House and about the process of archeological discovery. It will also help to ensure that the archeological excavations are conducted with maximum transparency and will instill confidence that the work is being completed with appropriate vigor and care.
The figure accompanying this briefing paper shows the preliminary NPS recommendation of a target area suitable for an archeological research study. The area delineated was drawn to maximize the research potential of the study while minimizing disruption and possible damage to critical existing infrastructure. The area that encompasses the main house, as well as the north end of the yard to the east, has been excluded from the recommended study area. In the discussion, above, the research potential of possible foundations of the main house was found to be minimal. In addition, excavation of the northern portion of this area would require excavation under the existing Market Street sidewalk. This would necessitate closing most or all of the width of the sidewalk to pedestrian traffic during the period of excavation and site restoration.
The southern end of the President's House site is excluded from the study area because it is situated under or directly adjacent to the LBC buildings or its exterior piers. Excavation of these areas would impede access to the LBC and might compromise the structural integrity of the building. An engineering study will be needed in order to determine with certainty how close excavation can safely come to the building; the southern boundary of the possible study area might have to be adjusted accordingly.
The area within the recommended study area includes approximately 45% of the previously unexcavated yard areas which are believed to have existed on the President's House site. The former yard areas are the locations within which there is the highest potential to uncover shaft features dating to the President's House period. In addition, this area includes the location of the bath house. As noted above, this is the only building extension which seems at all likely to have had a basement and corresponding foundation which might have survived twentieth century construction activities.
Only very preliminary cost estimates for an archeological research program can be offered at this time. The NPS estimates the costs for the program outlined here would range between $400,000 and $800,000. A well-written research design and a carefully considered engineering plan will help to contain costs.
It is anticipated that the cost of shoring and other excavation support will account for fully one third to one half of the anticipated project costs. In order to develop more accurate cost estimates it will be necessary to define the project area and to commission an engineering study on the costs of shoring and excavating that selected area.
Archeological costs will, by necessity, be contingent on the number of features investigated and the volume of artifacts recovered. These are cost factors that can only be estimated prior to excavation and will not be known with precision until excavation is completed.
NPS standards and professional ethics require that the cost of all aspects of an archeological project be included in the projects budget. This includes the cost incurred for processing, cataloging, analysis and curation of all recovered material and associated documentation. Production of a complete final report is also required. It is important to keep in mind that this structure applies even if material is recovered that is not directly germane to the particular research focus of a project.
Research excavation of the President's House site is estimated to require between six and eight weeks. This estimate does not include the time required for restoration of the area. Restoration of the soil to a safe, stable condition for construction of the commemoration could require a considerable amount of time and will be contingent on engineering requirements and specifications. Additional time will be required prior to the start of field work to allow for necessary contracting actions and design of a suitable excavation strategy. Completion of the analysis of recovered material and the preparation of a final report could take as long as eight to twelve months following the completion of field work.
Because of its location within the boundaries of Independence National Historical Park, excavation of the President's House site would have to conform to the Secretary of the Interior's Standards and Guidelines for Archeology and Historic Preservation and to NPS policy. The NPS would have to maintain review and approval authority over the project's research design, and would maintain oversight during the execution of that research design.
NPS fully recognizes that the President's House site is one of very great historical significance and that it carries tremendous cultural and emotional significance for community groups. The site has much to teach us about the birth of our nation and the intertwined themes of slavery and freedom.
In the face of what is known concerning the later development of the site, we cannot confidently predict that research excavations will yield information that will substantially increase our knowledge of the site and the people who lived and worked there during the President's House period. There is, however, at least the possibility that new knowledge could be gained from excavations at the site. If a consensus emerges among our partners and stakeholders that such an effort is desirable, the NPS would endorse a well designed archeological research program.
|RESOURCE RESEARCH POTENTIAL SURVIVAL PROBABILITY|
|Historic Ground Surfaces||High||Very Low|
|Foundation and Structural Remains — Main House||Very Low||High|
|Foundation and Structural Remains — Extensions and Out Buildings||High||Low|
|Shaft Features — Wells||Moderate||High|
|Shaft Features — Privies||Moderate||High|