Preserving Archaeological Remains In Situ : Three Case Studies in Trentino, Italy

© W. S. Maney & Son Ltd 2012 DOI 10.1179/1350503312Z.00000000020

conservation and mgmt of arch. sites, Vol. 14 Nos 1–2, 2012, 238–47

Preserving Archaeological Remains In Situ: Three Case Studies in Trentino, ItalyCristina Dal Rì, Susanna Fruet, Paolo Bellintani, Nicoletta Pisu Soprintendenza per i beni librari archivistici e archeologici, Provincia Autonoma di Trento

Nicola Macchioni, Benedetto Pizzo, Chiara CaprettiCNR IVALSA Istituto per la Valorizzazione del Legno e delle specie Arboree

The paper presents the results of the restoration and conservation work which has been carried out in three archaeological areas in the Autonomous Province of Trento. The areas, which have been opened to the public for more than ten years, are the open-air archaeological site of Monte S. Martino, Roman Tridentum (an underground site under the historical city centre of Trento), and Fiavé (a pile dwelling site in a peat bog). These areas present very different environmental characteristics and have therefore required different interventions according to their specifi c situation.

In order to reduce maintenance and extraordinary costs, appropriate conservation of the archaeological remains is required. This consists of methodologies of conservation according to the characteristics of the environment; continuous monitoring systems and indirect preventive intervention; and annual maintenance planning.

keywords archaeological sites, public access, conservation, maintenance, waterlogged wood

Introduction

The Soprintendenza per i Beni librari archivistici e archeologici (Archaeological

Heritage Offi ce) of the Autonomous Province of Trento, according to the Italian law,

is in charge of the protection, conservation, and enhancement of the archaeological

heritage. Among the fi fteen archaeological sites open to the public we have chosen

three examples. Each of them needs different conservation approaches.

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239PRESERVING ARCHAEOLOGICAL REMAINS IN SITU

1. The paper presents the history of the restoration work carried out since the

1980s until today in the open-air site of Monte S. Martino. We have analysed

and observed the mechanical resistance of the materials used in the last thirty

years, considering their relation with the climate conditions and the fact that

the remains have no roof covering.

2. In the case of the Roman Tridentum, we have taken into consideration a

restored area which is located in a protected underground space, where we have

carried out preventive intervention measures in order to prevent biological

decline. These measures consisted of integrated temperature, light, and

humidity monitoring system.

3. The pile dwelling site of Fiavé, which has been recently included in the

UNESCO Heritage List, is particularly interesting as far as the conservation of

the piles in wet land is concerned.

We have analysed the state of conservation of the poles and the wooden remains in

the water in situ since the 1970s thanks to a research programme carried out with the

CNR-IVALSA (National Research Centre) of Sesto Fiorentino (Firenze, Italia). The

aim of this project is to identify the best conservation methodologies in order to be

able to show them in the upcoming archaeological pile dwelling park of Fiavé.

Open-air archaeological site: Monte S. Martino

Cristina Dal Rì and Nicoletta Pisu

The Monte S. Martino area is situated above the village of Campi di Riva del Garda

at an altitude of 850 m a.s.l. to the north of Lake Garda, in a very important position

from a strategic and logistical point of view.

Archaeological investigations took place starting from the 1970s, leading to identi-

fi cation of an important Roman Age sanctuary dating back to between the fi rst

century bc and the fourth century ad (55×30 m) (Figure 1).

In 1996 new excavations were begun, at annual intervals, establishing the existence

of a previous settlement and a cult site dating back to the Iron Age, a sanctuary

dating back to the fi rst–fourth century ad and a settlement, probably military, dating

back to the fi fth–sixth century ad. This was followed by construction of the small

church of S. Martino and subsequent use of the terraces and plateaus of Monte San

Martino for agricultural purposes.

In the early 1980s the area was made into an open-air site, without the construction

of any roof covering. The climate is characterized by hot summers and cold winters

marked by snow and temperatures regularly going below freezing point (average

annual temperatures range from −5° C to + 25° C but no measurements of the

parameters have been made). According to the methods of the time, restoration work

was carried out by a construction company which reinforced the walls with cement

mortar, also reconstructing the last row of stones.

Excessive restoration intervention is not accepted any more from an archaeological

point of view. Cement mortars are not reversible and cause effl orescence and

deposits of crystals of salt on the archaeological remains.


240 CRISTINA DAL RÌ et al.

Following the renewed excavations at the end of the 1990s, the problem of con-

solidating the new archaeological remains presented itself. According to the modern

concept of restoration, we decided not to use any more cement-based mortars. Instead

we used a reversible material similar to the ancient lime-based mortar. Premixed

mortars based on hydraulic lime and sand (Fen-X Tassullo, Trento, Italia) were ini-

tially used. However, these were not considered satisfactory in terms of colour and

particle size, but even in the long term they proved to be resistant to low temperatures

and frost.

In order to improve the aesthetical aspect mortars made with local lime and sand,

sifted and mixed on site were used. The results were aesthetically satisfying, however

in these climatic conditions and without any roof covering the mortar disintegrated

very rapidly (in a wintertime) (Figure 2).

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fi gure 1 Site of Monte S. Martino. Area of the Roman sanctuary. Photograph Archivio Soprintendenza per i beni librari, archivistici e archeologici Provincia

Autonoma di Trento and by permission of the CNR-IVALSA (National Research Council of

Italy)



In the last years a general programme concerning restoration and excavation work

started again. Interventions were carried out in 2010 and 2011 by Diego Malvestio.

Scavi e restauri archeologici, Concordia Sagittaria (Venezia, Italia).

In the light of this experience, a compromise has been found, making it possible to

satisfy deontological and aesthetic canons and resist freezing-thawing: the solution

adopted by us was to insert a very small percentage (about 0.02 or 0.03) of white lime

cement (Aquila Bianca Portland B LL 32.2R) into the mixture. The mortar which has

been used to fi x the upper part of the walls was further strengthened with cement in

order to reinforce the most critical point where water stagnation and freezing can

occur.

We also noticed that a better and most durable result can be obtained by cleaning

out properly earth, pebbles, and ancient mortar from the gap between bricks. In the

last years, in order to enhance the strength and resistance of walls, lime-based mortar

(Albaria TM injection BASF) was also injected at depth until return.

These procedures avoid the mortar crumbling and the rapid growth of vegetation

and weeds.

It is indispensable to check the state of conservation of the works annually and to

carry out regular maintenance procedures, such as the fi lling of cracks and removal

of plants, with relative biocide treatments.

fi gure 2 Site of Monte S. Martino. Detail of the decay of the sand and lime based mortar on the walls after winter. Photograph Archivio

Soprintendenza per i beni

librari, archivistici e archeo-

logici Provincia Autonoma di

Trento and by permission of

the CNR-IVALSA (National

Research Council of Italy)

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Archaeological site: the Roman city of Tridentum

Cristina Dal Rì and Susanna FruetFollowing restoration work on the Teatro Sociale in Trento (1990–2000) archaeo-

logical excavations were carried out bringing to light part of the ancient Roman city

of Tridentum (fi rst century bc–sixth century ad) under the current level of the theatre.

This extensive area is made up of public spaces and private areas: dwellings

with fl oors decorated with mosaics, a long stretch of the eastern city walls, and an

extensive section of street paved with large slabs of local red stone. Below the street,

various ducts belonging to an extensive system of sewers were brought to light.

Restoration work was carried out in the 1990s and included all archaeological

remains: walls, sewers realized in bricks and other parts in terracotta, mosaics, and

slabs of red limestone. Methodologies and materials used have been chosen according

to the principles of reversibility and compatibility with ancient materials. As far

as walls are concerned, Lafarge lime-based mortars, slaked lime, sand, and diluted

acrylic resin (Primal AC33, Bresciani, Milano, Italia) were used. Stone strengthening

was carried out by using ethyl silicate (RC70 e RC80 — Rhodorsil — Rhodia

Siliconi Italia).

The archaeological area was opened to the public in 2001 and offers a wide range

of activities: educational initiatives, meetings, conferences, exhibitions, and perform-

ances (Figure 3). Ten years after the site was opened up to the public, the state of

fi gure 3 The Roman city of Tridentum. Photograph Archivio Soprintendenza per i beni librari, archivistici e archeologici Provincia


Italy)

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‘health’ of the area can be considered to be good, thanks to heating system for the

winter and air-conditioning in summer.

There are no particular problems in terms of conservation apart from those linked

to the dust deposits from all the structures within the area and at the same time

structural stability checks of such structures, growth of micro-organisms, or phenom-

ena of biological colonization, located above all in the sewers, which are sealed by

glass and house a number of lights.

Ordinary maintenance of the site, which takes place every two years, contributes

signifi cantly to conserving the archaeological structures properly and also allows

monitoring.

The procedures are carried out with the assistance of vacuum cleaners and brushe s

for cleaning surfaces and removing superfi cial deposits, whereas for the mosaic and

street paving slabs cleaning takes place using water spray and gentle sponging; a

protective and strengthening ethyl silicate (RC80 — Rhodorsil — Rhodia Siliconi

Italia) coating has been applied to the red limestone paving slabs of the street. At the

same time structural stability checks of such structures, with renovation of mortar

joints and securing of loose stones is carried out.

To deal with this problem, a number of direct and indirect measures have been

taken, such as:

- Substitution of incandescent light bulbs with low energy consumption light

bulbs,

- Substitution of some glass covering panels with metal grids, in order to assist

ventilation of the duct,

- localized treatment with broad spectrum biocides (Biotin R — CTS, Vicenza,

Italia).

To date this intervention would seem to have resolved the problem. Maintenance was

last carried out in 2009 by Ambra Conservazione e Restauro (Milano, Italia).

Archaeological site in a wetland area: the lake dwelling at Fiavè

Cristina Dal Rì, Paolo Bellintani, Nicola Macchioni, Benedetto Pizzo, and Chiara CaprettiThe Fiavè peat bog (formerly Lake Carera) is situated in the south-west of Trentino

at an altitude of 646 m a.s.l., 10 km north of Lake Garda.

Excavation works carried out between 1969 and 1975 by Renato Perini allowed to

identify seven anthropization zones and various lake dwellings dating back between

the fourth and second millennium bc. In zone 2 a pile-dwelling settlement has been

identifi ed (about 1800–1500 bc in the last phase of the Early Bronze Age–beginning

of the Middle Bronze Age). The settlement is characterized by piles up to 9–10 m long

(829 piles in 475 m2 excavation area).

In the nearby zone 1 (about 1500–1350 bc — the last phase of the Middle Bronze

Age) an elaborate system of ‘grid’ foundations and a stockade along the eastern side

of the village has been conserved (Figure 4). Following the excavations in the 1970s,

the piles, in spruce, larch, silver fi r, and Scots pine, have remained in situ in very

different conditions as compared to those originally experienced: partially or totally



immersed in the groundwater, representing the main tourist attraction in the area.

After the latest interventions of excavation and research, dated back to 1994, many

organisms have settled permanently on both the submerged parts of the poles and on

those emerging: algae, molluscs were anchored to the posts, and other organisms, like

plants (herbs and willows), were rooted on the heads of the poles emerging from

water. In 2009 a cleaning intervention was made in the lake basin and the emerged

parts of the poles have been cleaned by the vegetation from the tops and root

systems.

In order to determine the degree of deterioration a cooperation with the National

Research Council of Italy CNR-IVALSA (Firenze Italia) was started, also considering

the plan of the creation of an archaeological park.

In summer 2010 the water table in the zone 1 was lowered. Following this interven-

tion we have been able to survey the wooden remains of the settlements dated to the

Late Neolithic (Fiavè 1 c. 3800–3600 bc), to the Middle Bronze Age and to the Late

Bronze Age (Fiavè 6 and 7 c. 1500–1200 bc), which are situated on a small morainic

hill in the centre of the lake and the wooden remains of the cross-linked structure

(Fiavè 6).

fi gure 4 Fiavè. Pile dwellings: zones 1 and 2 excavation works by R. Perini 1969–75. Photograph Archivio Soprintendenza per i beni librari, archivistici e archeologici Provincia


Italy)



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On these remains a new georeferenced topographic survey was carried out. We also

took 101 samples on 81 wooden artefacts. The samples, crossing the piles completely

at several points, were taken using a ‘Pressler borer’1 (Figure 5). There were consider-

able problems in extracting the core sample from parts underwater (poor state of

conservation, sucker effect, etc.).

The following tests were undertaken on these samples:

- anatomical (micromorphological) characterization, by optical and Scanning

Electron Microscope (SEM Philps XL 20) to evaluate the state of preservation

of the cell walls and to trace the type of organisms that caused the decay;

- chemical characterization, to measure the residual percentage of extractives,

holocellulose, lignin, and ashes. Spectroscopic techniques will also allow evalu-

ating more in detail the distribution of the chemical components from the

surface to the depth of the artefacts. More specifi cally, this kind of test will be

carried out also on a quantitative basis, after a preliminary calibration proce-

dure, thus to handle very limited amounts of material. Tests will be performed

on a Alpha Bruker Optics instruments equipped with an ATR (Attenuated

Total Refl ectance) device, which allow taking measurements directly on

samples, without any preliminary modifi cation;

- physical characterization to measure the decay through the measurement and

calculation of the densities and the Maximum Water Content (MWC, %).

It should be underlined that there are no analytical references to the state of preserva-

tion at the time of fi nding.

On the basis of visual evaluation and state of the core samples extracted, fi rst

impressions regarding the state of preservation are not good: there is a seriously

deteriorated outer layer which has provided support and food for various categories

of plant and animal organisms. Inside the piles, it has been possible to note the

activity of organisms living in wetland environments, feeding on decomposing plant

debris. Indeed, the parts of the wood immersed in the sediment only apparently

look like fresh wood, whereas the material has actually lost a substantial part of its

organic consistency.

The data are still being processed. The results will be used to verify whether the

in situ conservation of structural timber is feasible or not, in order to make the

archaeological structures enjoyable by the public through the realization of the ‘Park

of the pile dwellings’, or whether other solutions should be considered, and probably

2

fi gure 5 Sample of pile-dwelling pole taken using a ‘Pressler borer’.Photograph by CNR-IVALSA



start a new study for the reburial of at least part of the poles. At present, no

evidences of other similar experiences or processes of reburial carried out on wood

preserved in peat bogs have been found in literature. Moreover, it is also interesting

that wood material has been preserved in water during last approx. thirty years,

instead of in peat bog like in previous thousands of years. Therefore, the data that

will be collected on the wooden elements of Fiavè will represent an important mile-

stone in detecting the effect of an eventual reburial, or alternatively of an eventual

exhibition, on the future state of preservations of artefacts.

Note1 Sampling was carried out by CNR, CORA — Ricerche archeologiche, BRAIDOSUB.

Bibliography

Bellintani, P., Dal Rì, C., Macchioni, N., Pizzo, B., Capretti, C., De Gasperi, N., and Moranti, N. 2011. Dopo 40

anni. Diagnostica sui pali delle aree di scavo Perini e ipotesi di lavoro per la conservazione delle palafi tte

di Fiavè. Unpublished paper for: International Conference ‘Pile-dwellings: Investigations, Conservation,

Enhancement’, Desenzano del Garda, 6–8 October.

Capretti, C., Macchioni, N., Pizzo, B., Galotta, G., Giachi, G., and Giampaola, D. 2008. The Characterisation

of Waterlogged Archaeological Wood: The Three Roman Ships Found in Naples. Archaeometry, 50(5).

University of Oxford, 855–76.

Ciurletti, G. 2000. Trento romana. Archeologia e urbanistica. In: Storia del Trentino, L’età romana, Volume I.

Istituto Trentino di Cultura, Trento, pp. 287–346.

Ciurletti, G. ed. 2007. Fra il Garda e le Alpi di Ledro Monte S. Martino il luogo di culto (ricerche e scavi 1969–

1979). Giunta della Provincia Autonoma di Trento, Soprintendenza per i beni Archeologici, Trento.

Dal Rì, C., Bellintani, P., Macchioni, N., Pizzo, B., and Capretti, C. 2011. Preliminary Studies for the Conserva-

tion of Wooden Poles of the Pile Dwelling in Fiavè (North East, Italy). International Conference IKUWA 4

‘Managing the Underwater Cultural Heritage’. Zadar (Croatia), 29 September–2 October.[Online] Available

at: <http://www.ikuwa4.com.>.

Marzatico, F. 2003. Aspetti della storia delle ricerche nella torbiera di Fiavè. In: P. Bellintani and L. Moser, eds.

Archeologie sperimenatali. Metodologie ed esperienze fra verifi ca, riproduzione, comunicazione e simulazione.

Provincia Autonoma di Trento, Servizio Beni Culturali, Uffi cio Beni Archeologici, Trento, pp. 171–80.

Perini, R. 1984. Scavi archeologici nella zona palafi tticola di Fiavè–Carera, Parte I, campagne 1969–1976. Situazi-

one dei depositi e dei resti strutturali. Patrimonio storico artistico del Trentino, 8, Provincia Autonoma di

Trento, Servizio Beni Culturali, Trento.

Pulga, S. 1999. Climatologia nella conservazione di scavi archeologici coperti. In: C. Dal Rì and S. Fruet, eds.

Climatologia applicata alla conservazione dei beni archeologici e storico artistici, Incontri di restauro 2.

Provincia Autonoma di Trento, Servizio Beni Culturali, Trento, pp. 88–125.

Pedelì, C.and Pulga S. 2002. Pratiche conservative sullo scavo archeologico, principi e metodi. MIC (Museo

Internazionale delle Ceramiche in Faenza), Firenze.

Notes on contributors

Cristina Dal Rì, conservator-restorer, at the Archaeological Heritage Offi ce of the

Autonomous Province of Trento. She is in charge of the conservation restoration of

all kind of archaeological remains and of the archaeological areas. Her specialization

area is the conservation of wet organic materials.

Contact: Cristina Dal Rì, Soprintendenza per i beni librari archivistici e archeo-

logici, Provincia Autonoma di Trento, Laboratorio di restauro, Via Aosta 1, 38122

Trento, Italia. Email: [email protected]

3

4



Susanna Fruet, conservator-restorer, at the Archaeological Heritage Offi ce of the

Autonomous Province of Trento. She is in charge of the conservation restoration of

all kind of archaeological remains and of the archaeological areas. Her specialization

area is the conservation of metal materials.

Contact: Susanna Fruet, Soprintendenza per i beni librari archivistici e archeo-

logici, Provincia Autonoma di Trento, Laboratorio di restauro, Via Aosta 1, 38122

Trento, Italia. Email: [email protected]

Paolo Bellintani, PhD, graduated in Paletnology, and is archaeologist at the Archaeo-

logical Heritage Offi ce of the Autonomous Province of Trento, he is in charge of the

archaeological pile-dwelling site, museum, and park of Fiavé.

Contact: Paolo Bellintani, Soprintendenza per i beni librari archivistici e archeo-

logici, Provincia Autonoma di Trento, Via Aosta 1, 38122 Trento, Italia. Email:

[email protected]

Nicoletta Pisu, PhD, graduated in Medieval Archaeology, and is archaeologist at the

Archaeological Heritage Offi ce of the Autonomous Province of Trento. She is in

charge of the excavation and restoration works on the archaeological site of Monte

S. Martino.

Contact: Nicoletta Pisu, Soprintendenza per i beni librari archivistici e archeo-

logici, Provincia Autonoma di Trento, Via Aosta 1, 38122 Trento, Italia. Email:

[email protected]

Nicola Macchioni, PhD, graduated in Forest Science and is currently Researcher at

CNR-IVALSA, where he is coordinator of the Wood Conservation Department. He

is also in charge of the ‘Laboratory of Wood Anatomy’. He developed a large experi-

ence in diagnosis applied to the wooden Cultural Heritage, from timber structures to

wood statues, including archaeological wood.

Contact: Nicola Macchioni, CNR-IVALSA Istituto per la Valorizzazione del Legno

e delle specie Arboree, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze,

Italia. Email: [email protected]

Benedetto Pizzo, PhD, graduated in Chemical Engineering and is currently Researche r

at CNR-IVALSA, where he is in charge of the ‘Laboratory of Chemistry of Wood

and Wood Products’. He developed a large experience in the characterization of wood

artifacts belonging to the Cultural Heritage and of the materials used for restoration.

He matured a specifi c experience in the characterization and in the conservation of

waterlogged archaeological wood.

Contact: Benedetto Pizzo, CNR-IVALSA Istituto per la Valorizzazione del Legno

e delle specie Arboree, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze,


Chiara Capretti, PhD, graduated in Forest Science and is currently Researcher at

CNR-IVALSA. She developed a broad experience on microscopy applied to archaeo-

logical wooden artifacts and more generally on the diagnosis of waterlogged wood.

Contact: Chiara Capretti, CNR-IVALSA Istituto per la Valorizzazione del Legno e

delle specie Arboree, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze,



Author Query

Journal title: CMA

Volume and issue: 14-1-2

Article title: Preserving Archaeological Remains In Situ: Three Case Studies in

Trentino, Italy

Author name: Cristina Dal Rì et al.

QUERY NO. QUERY DETAILS

1 In the last few years?

2 ‘from 81 artefacts’ rather than ‘on 81 artefacts’?

3 “for around the last thirty years’?

4 Is ‘University of Oxford needed in this ref? Not usually included

with journals


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