The aqueduct of Grumentum

by Francesco Tarlano

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The remains of the aqueduct that served the city of Grumentum have been the subject of surveys and descriptions since the eighteenth century.

The local historical sources agree about displaying various information useful to the topographical arrangement of the monument: first of all about the positioning of the founts in locality Castagneto, at the foot of the hill on which stands the city of Moliterno. Proceeding northward, after crossing the stream Sciaura with a small bridge, the aqueduct continued through the quarters Pantano, Mercato and Valle del Monaco, to arrive until the southern side of the built-up area and then inside the city.

Nowadays however are visible just four stretches of the aqueduct in locality Mercato (Sarconi), Fontana del Principe, Spineta and San Giuseppe (Grumento Nova). The remains were rediscovered and subsequently investigated by Liliana Giardino, through campaigns of archaeological survey directed by herself. On the basis of her studies has been also possible to reconstruct the layout, the building techniques used and to propose chronological hypotheses on the artifact.

The length of the infrastructure is about 5 km, split on a not straight path but strongly influenced by orography and clivometria of the territory on which was set.

Starting from the area where according to the  sources was located the fount from which were collected the waters, at an altitude of about 660 meters above sea level, the infrastructure had to overcome a series of natural obstacles that characterize the physical geography of the area before reaching the city at an altitude of about 590 meters above sea level, so after passing a drop of about 70 meters.

The work was carried out with two different types of structures: while in the valley of Spineta were made some arches that served to raise the degree of slope and could accommodate two tiers of channels, in the final stretch on the other hand the aqueduct was inserted on a full masonry structure.

This probably arose from the need for greater stability of the structure, which was going to set in the final stretch on a embankment artificially raised to overcome a very sloping zone, keeping the slope as constant as possible; to overcome finally the road director that from the southern gate of the city was oriented to west, Roman engineers built a new bridge connecting with the slopes of the plain on which stood the city.

Inside the walls then should be the structure designated as probable Castellum Aquae (the catchment of water from the aqueduct) of the city.

Regarding the distribution of water in the city we have news about the discovery of four specimens of fistulae in lead two of which supplied the Domus with mosaics, the third another building near the  Capitolium, the fourth a building to south-west of the amphitheater, probably the imperial baths.

In locality Castagneto, at the foot of the hill of Moliterno, likely catchment area of ​​the aqueduct because rich of fresh water sources, until today archaeological traces relative to Roman aqueduct have not been found; however, the cartography shows the presence of a Renaissance age aqueduct that served the city of Sarconi that captured its water from one of these sources. In locality Mercato near Sarconi is preserved a continuous wall in Roman concrete (opus caementicium) with external vestment in almost opus reticolatum by a height of about 50 cm and a length of about 1 km; at the upper part of the wall stands out the logline in which were placed the pipes carrying water to the city.

Lombardi in 1832 signaled a stretch of aquecuct in the district Pantano at the south of Sarconi, today no longer distinguishable.

In locality Spineta, along the valley extending to south of the Roman city, about 500 meters to east from the public road, are still visible at least 51 wall buildings, which come one after the other for about 330 meters along the valley.

The pillars have external facing in opus reticulatum and an inner core in opus caementicium, with stones of various size hold together with mortar. Among the pillars preserved one after the other it is measured the distance of 1.85 meters (corresponding to the extension of the arches which had to soar above them). The maximum height reached by the remains is 4.50 meters, while the minimum reaches a few centimeters compared to the current walking surface.

About 150 meters to north, still perfectly aligned with the arches of Pilieri just described, we can notice signs of structures on the surface of grass, related to the infrastructure.

In locality Fontana del Principe is preserved a continuous wall oriented SSW-NNE, about 60 meters long, whose maximum height reaches 2 meters, the minimum about 50 centimeters.

The structure is set on an artificial embankment probably raised at the same time with the implementation of the section of the aqueduct, to maintain a constant slope next to the elevated plateau of Grumentum.

In the upper part is still visible the logline holding the lead pipes; the logline was covered in opus signinum and was approximately 35 cm wide and equally high, taking a content of about 12 liters per linear meter of water. The coverage of the logline was probably at the Capuchin style, plan or vault, but we don’t have any trace of it.

The external facing surrounding the inner core in Roman concrete looks like the summary of different construction techniques, which show alterations in later ages.

About 50 meters north-west from the chapel of San Giuseppe, situated near the southern gate of Grumentum, are visible, inside the archaeological park, the remains of the final stretch of the aqueduct, set on the slope to the southwestern part of the city.

This section of the aqueduct was placed on a continuous structure in opus reticulatum, on the contrary of the stretch located along the valley in locality Spineta, which had a system of arches on which they were made to run the channels that carried water.

This section was built with an external facing in reticulated work (opus reticulatum), while the inner core was made in Roman concrete with stones of variable sizes and mortar; however, in some parts are visible actions of a later period, made by opus vittatum, with pebbles alternating with bricks.

In the points in which it is better preserved, the wall of the building reaches a height of 2.50 meters, but some remains do not exceed 40-50 centimeters in height.

To southwest of the final stretch of the aqueduct, on the highest point of the plateau, it’s possible to see the square perimeter of a structure uplifted no longer existing perfectly alignment with the maximum decumanus of Grumentum.

Within this perimeter is visible a small rural house now destroyed, evidently built with materials belonging to the structure.

Moreover, to the west of the perimeter, it was found a large pile of debris characterized by the presence of blocks and stones of different sizes.

According to recent hypotheses these remains would be referred to the Castellum Aquae which served as a basin for collecting water coming from pipes and as a starting point for the branch of the channels in the urban section.

The construction of the aqueduct is dated around the middle of the first century B.C., and it is used as only element dating the building technique, because of the absence of excavation data.

Copyright text and images (where there aren’t other references) by Francesco Tarlano.