Guidelines for Rehabilitating Cultural Landscapes
In Rehabilitation, a cultural landscape’s character-defining features and materials are protected and maintained as they are in the treatment Preservation; however, a determination is made prior to work that a greater amount of existing historic fabric has become damaged or deteriorated over time and, as a result, more repair and replacement will be required. The Standards for Rehabilitation and Guidelines for Rehabilitation allow the replacement of extensively deteriorated, damaged, or missing features using either traditional or substitute materials. For example, Rehabilitation may include replacing a crushed bluestone carriage drive with a rolled aggregate finish or replacing shaded-out understory shrubs with more shade-tolerant species. Of the four treatments, only Rehabilitation includes an opportunity to make possible an efficient contemporary use through alterations and additions; for example, replacing tillage with permanent grasslands to support a new system of livestock grazing or introducing new turf management to a park’s open meadows to support sports field use.
Like Preservation, guidance for the treatment Rehabilitation begins with recommendations to identify those landscape features and materials important to the landscape’s historic character and which must be retained. Therefore, guidance on identifying, retaining, and preserving character-defining features is always given first. An overall evaluation of existing conditions should always begin at this level. The character of a cultural landscape is defined by its spatial organization and land patterns; features such as topography, vegetation, and circulation; and materials, such as an embedded aggregate pavement.
After identifying those materials and features that are important and must be retained in the process of Rehabilitation work, then protecting and maintaining them are addressed. Protection generally involves the least degree of intervention and is preparatory to other work; it may be accomplished through permanent or temporary measures. For example, protection includes restricting access to fragile earthworks or cabling a tree to protect against breakage. Maintenance includes daily, seasonal, and cyclical tasks, and the techniques, methods and materials used to implement them. For example, repointing a stone footbridge, pruning a hedge, or rotating crops.
When existing conditions of character-defining materials and portions of features warrant more extensive work, repairing is recommended. Rehabilitation guidance for the repair of historic features and materials, such as brick pavements, masonry walls, and wire fencing, begins with the least degree of intervention possible. Such work could include regrading a section of a silted swale, aerating soil, or reclaiming a segment of meadow edge. Repairing also includes the limited replacement in kind of extensively deteriorated materials or parts of features, or replacement in kind of materials or parts of features lost due to seasonal change. Using material which matches the historic in design, color, and texture is always the preferred option; however, substitute material is acceptable if the material conveys the same visual appearance as the historic period. For example, spring replacement of annual beds; in an orchard, planting a tree of new stock that matches the historic form, and composition; or, using a spun aluminum baluster where a cast zinc member was beyond repair.
Following repair in the hierarchy, Rehabilitation guidance is provided for replacing an entire character-defining feature with new material because the level of deterioration or damage precludes repair. Examples include replacing a farm’s drought-damaged pasture or replacing a corroded cast iron fence surrounding a reservoir. Like the guidance for repair, the preferred option is always replacement of the entire feature in kind. Because this approach may not always be technically, economically, or environmentally feasible, the use of compatible substitute materials can be considered. Whatever level of replacement takes place, the historic features and materials should serve as a guide to the work.
While the Guidelines recommend the replacement of an entire feature that is extensively deteriorated or damaged, they never recommend removal and replacement with new material if repair is possible.
When an entire feature is missing, the landscape’s historic character is diminished. Although accepting the loss is one possibility, where an important feature is missing, its replacement is always recommended in the Rehabilitation guidelines as the first or preferred, course of action. Thus, if adequate historical, pictorial, and physical documentation exists so that the feature may be accurately reproduced, and if it is desirable to re-establish the feature as part of the landscape’s historical appearance, then planning, designing and installing a new feature based on such information is appropriate.
A second course of action for the replacement feature is a new design that is compatible with the remaining character-defining features of the historic landscape. The new design should always take into account the spatial organization and land patterns, features, and materials of the cultural landscape itself and, most importantly, should be clearly differentiated so that a false historical appearance is not created. For example, replacing a set of lost granite steps with concrete steps which match the historic in location, size, scale, color and texture or replacing a mass of Eastern hemlocks with Japanese spruce.
When alterations to a cultural landscape are needed to assure its continued use, it is most important that such alterations do not radically change, obscure, or destroy character-defining spatial organization and land patterns or features and materials. Alterations may include enclosing a septic system, increasing lighting footcandles, extending acceleration and deceleration lanes on parkways, or, adding new planting to screen a contemporary use or facility. Such work may also include the selective removal of features that detract from the overall historic character.
The installation of additions to a cultural landscape may seem to be essential for the new use, but it is emphasized in the Rehabilitation guidelines that such new additions should be avoided, if possible, and considered only after it is determined that those needs cannot be met by altering secondary, i.e., non character-defining, spatial organization and land patterns or features. If, after a thorough evaluation of alternative solutions, a new addition is still judged to be the only viable alterative, it should be planned, designed, and installed to be clearly differentiated from the character-defining features, so that these features are not radically changed, obscured, damaged, or destroyed. For example, constructing a parking lot in a secondary meadow that is enclosed by existing vegetation or installing contemporary trail signage that is compatible with the historic character of a landscape.
Additions and alterations to cultural landscapes are referenced within specific sections of the Rehabilitation guidelines such as Topography, Vegetation and Water Features.
These sections of the Rehabilitation guidance address work done to meet accessibility requirements; health and safety code; environmental requirements; or limited retrofitting measures to improve energy efficiency. Although this work is quite often an important aspect of preservation projects, it is usually not part of the overall process of protecting, stabilizing, conserving, or repairing character-defining features; rather, such work is assessed for its potential negative impact on the landscape’s character. For this reason, particular care must be taken not to obscure, damage, or destroy character-defining materials or features in the process of undertaking work to meet code and energy requirements.