Preventive conservation plan

M. JOSÉ GRACIA TARRAGONA

Preventive conservation plan of the Roman Villa of Els Munts

BEFORE DISCUSSING THE PREVENTIVE CONSERVATION PLAN, I BELIEVE IT IS ESSENTIAL TO RECALL THE DEFINITION OF THE BASIC TERMS ON WHICH OUR JOB IS BASED. THESE ARE TERMS WE USE EVERY DAY, AND IT IS IMPORTANT TO BEAR THEM IN MIND.

The UNE-EN 15898 standard, dated March 2012, defines conservation as “measures and actions that seek to safeguard the cultural heritage while respecting its heritage significance, including its accessibility to present and future generations.

Conservation encompasses preventive conservation, remedial conservation and restoration.”

 Preventive conservation is defined in this standard as “measures and actions that seek to prevent or minimise any harm or damage, deterioration and loss in the future, and in consequence any invasive intervention”.

 Remedial conservation is described as “actions applied directly to an asset to stop deterioration and/or harm or damages”.

 Restoration: “actions conducted on a stable or stabilised asset that seek to improve its recognisability, understanding and/or use, while respecting its heritage significance and the materials and techniques used”.

In 2011, with the approval of the National Preventive Conservation Plan, the meaning of the concept of preventive conservation was set and became a fundamental criterion based on which methodologies and actions are established. The

Before and after the tasks aimed at eliminating the plants above. Photo: M. José Gracia During the work to track and document the site’s state of conservation. Photo: M. José Gracia

definition is expanded and preventive conservation is considered:

“A strategy for conserving the cultural heritage that proposes a systematic working method to identify, evaluate, detect and control the risks of deterioration of objects, collections and, by extension, any cultural asset. Its fundamental objective is to eliminate or minimise these risks by acting at the root of the problems, which generally lie in factors external to the cultural assets, and to thus prevent their deterioration or loss and the need to undertake drastic and costly treatments applied to the assets themselves”.

From the start, the principles of preventive conservation have been grounded on the exchange of knowledge, scientific information and training. The preventive conservation strategy adopted in 2011 encompasses aspects like sustainability, resource optimisation and the accessibility of the heritage. The ultimate goal is to control risks and act at the root of the problem, not its effects on the assets. It is an essential shift in strategy. It was gradually implemented as a

Close-up of the location of the device to track humidity and temperature data. Photo: M. José Gracia strategy in the general policies and plans, and this steady upswing in implementation has also reached our sites. Aware of the importance of and need for this change, the Centre for the Restoration of Artefacts of Catalonia has been working for several years to develop preventive conservation strategies which are advancing parallel to the remedial conservation and restoration work which was already being undertaken. We are still in the early stages, and we are making slow but steady progress. Since 2019, we have been working to develop the Preventive Conservation Plan of the site of the Roman villa of Els Munts. The plan aims to be a tool to coordinate all the tasks associated with the conservation of this space, which will also help set a calendar, assign priority and budget the site’s different needs with coordinated efforts and resources. Currently, the pandemic has slowed down the pace of work but not stopped it.

It was created with the desire for standardisation, to use internationally recognised methodologies and terminology on conservation matters, and with the goal of fostering knowledge transfer and dissemination, so professionals and managers at other sites are able to apply the lessons learned, and vice-versa.

To accomplish this, it requires the involvement of all the stakeholders associated with the site. Interdisciplinary teams, rational methodologies and constant budgetary allocations are needed. The objective is to develop a consensual strategy and to establish priorities based on corroborated and quantified studies and data (not only observation and experience). We are working with the goal of achieving comprehensive management of the site’s conservation. What is the working method of the Preventive Conservation Plan (PCP)? The working methodology to develop a PCP is based on 4 phases:

1. Documentation analysis of the cultural asset and its context.

2. Risk analysis: identification, valuation, definition of priorities and proposal of urgent interventions.

3. Design and implementation of procedures

and protocols: proposals for operation; systematic working procedures; maintenance protocols; detection and response mechanisms to emergencies; and proposals for corrective measures (remedial and preventive).

4. Verification

As mentioned above, we are in a very early stage of the Plan. We are working simultaneously on phases 1 and 2. On the one hand, we are arranging the existing information: graphic documentation, reports, studies and analyses, everything associated with the site’s conservation and restoration. On the other, a diagnosis of the state of conservation and a risk assessment are being conducted, and a tool is being conceived in order to integrate and interrelate all this information.

The risk assessment and identification of the agents causing deterioration are fundamental Being able to recognise the likelihood that a certain deterioration may appear given a spe-

cific alteration agent (risk) and controlling these agents will enable us to prevent and anticipate damage and thus lower the interventions on the elements.

In this sense, monitoring has startedto track the agents detected and the damage they may cause.

Additionally, in recent years resources have been allocated to conduct a series of complementary studies, including:

1. Photogrammetry of the crypto-porch and the 6 rooms in the domus next to it, and mapping pathologies and risk zones

2. Study of salts: • Determination of the mineralogical composition of the efflorescence via X-ray diffraction with an X’pert Pro MRD diffractometer and specific measuring software

3. Study and identification of mortar: • Granulometric study • Determination of the mineralogical composition of the adhesive and the fine sand (size fraction under 0.063 mm) • Determination of the degree of hydraulicity of an adhesive • Determination of the open porosity and apparent and relative density of each mortar according to the UNE-EN 83980:2014 standard • Advice and proposals for new mortars for restoration

4. Study to identify the most appropriate material to remove the protective layers applied to the murals (mostly Paraloid® B72)

5. Study of the conductivity of the walls • Measurement of the conductivity of the walls via agarose disks • Mapping the data taken on the orthophotographs of the walls studied

In turn, the National Archaeology Museum of Tarragona (MNAT) has undertaken a study on rainwater, which is extremely important given that the agent of deterioration with the most harmful effects on the site right now is water. Its effects are the main direct or indirect cause of the majority of pathologies detected.

There are also plans for a new roof, long called for, which apparently is finally going to be made, albeit partially.

All this knowledge will be used to develop a rigorous maintenance plan. The programme will entail drawing up a series of documents which will be used to organise the periodic actions that must be made and that ensure control over the actions implemented. This programme will also include protocols on public uses and management, safety, control of vegetation, etc.

Obviously the preventive conservation proposals do not halt the other projects planned, and remedial conservation and restoration tasks continue to be undertaken. Preventive conservation is necessarily associated with remedial conservation, given that to prevent certain risks and improve resistance to the agent of deterioration, sometimes interventions are needed on elements and/or structures.

A variety of urgent interventions have been made to stabilise elements in the site, which are joined by restoration of the wall claddings and mosaics conserved in the crypto-porch.

The need for action is general throughout the entire site, but for the time being the efforts have focused particularly on acting in the zone of the crypto-porch and the rooms adjacent to the domus, with occasional interventions in the reservoir known as “la Tartana” and in the Mithraeum as well.

We will continue to develop the Plan, and we also hope to augment the monetary, material and human resources.

DETAILS

GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: site | DATE/ERA: Roman, from the 1st century BC to the 7th century AD | LOCATION: National Archaeology Museum of Tarragona. Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: 14145 | CATALOGUING: Archaeological ensemble of Tàrraco declared UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA