contact: Jeff Matthews

    chapter 3 - directly below      chapter 4, here               chapter 5, here           chapter 6, here
                                                (Distribution of Cavities)      (Underground Waters)     (geotechnical problems)

   

1) Methods of mining

A brief review of how extracting minerals from the subsoil for construction material may explain some of the problems of cave-insand shifting in the terrain.

Pozzolana and sand. Pozzolana, whether from primary sedimentation or disturbed in some fashion (and thus mixed with sand strata), has always been extracted in the simplest way: open-pit cutting and subsequent removal of inclined wall fronts either by cutting steps into the surface or by using the natural slope of the terrain. Since the beginning of the 1900s, there have a few rare examples of funnel extraction (the Canadian system) when situations require that the panoramic view from a hill not be disturbed. With the longer reach of modern mechanical equipment, however, extraction is done only from the foot of the hill, knocking down the slope as work proceeds.

Lapilli pumice. Leaving aside the narrower pumice strata that have been spoiled by surrounding terrain, extractable lapilli are found in level strata as thick as two meters at different elevations in the countryside. The use of white pumice is ancient, indeed. It has always been worked as the stone for barrel vaults, domes. etc. and is the pride of the building trade in the Gulf of Naples. The mixture of pumice with primary pozzolana and slaked lime, thrown and worked onto curved surfaces (to avoid cracks caused by fluctuating ambient temperature) has been use for two-thousand years.

In building multi-story and lighter-weight structures, however, they have tried to use the same material in the form of slabs or plates mounted into a framework (as in the protective coverings of terraced roofs).The cracks between plates, however, make the material much less efficient in coping with outside changes of temperature. Lapillo has a great many uses today in what is called “prefabricated” construction. After a period of time when it was little used, white lapillo has made a comeback as partition blocks and load-bearing supports in basements.

Today, only open-pit extracting is permitted, but until the first decades of this century [the 1900s], the material was extracted from underground chambers and shafts with the rare exception of smaller openings,where possible, cut into the front of pozzolana quarries. Access was by way of circular, vertical well shafts, never covered, to the bank of lapillo pumice generally at about 6 to 10 meters below the surface, occasionally deeper. From the bottom of the well, at the base of the lapillo bank, a series of shafts were then dug out like spokes off of a hub, each a few meters wide and from 10 to 15 meters long. When the extraction was finished, only the central shaft was filled back up. Waste rock was used until a bit before the surface and the rest was filled with earth.

The depth of the shafts and the presence of tree roots usually meant that the level surface above did not sink in to any noticeable degree. Below ground, however, around the central well, where it wasimpossible to shore up the sections where the spokes joined the hub, the space was precarious and could cave in. Such cave-ins became more likely if overlying soil was disturbed by the removal of large trees with their root systems and where construction on the surface interfered with an already shaky equilibrium.* This kind of digging always took place in those parts of town where the primary minerals were the most abundant; that meant the hills of Vomero, Capodimonte and Capodichino.

    *Recent episodes of sudden cave-ins include one in 1957 on via Piscicelli in Vomero (and again up in the Vomero hills in Sept,         1967, on via E. Cortese) and on via de Pinedo (at the crossing of via Baronie) in 1964 at Capodichino. Indeed, during an                     inspection of the run-off collector, 22 meters below the above-mentioned via de Pinedo, some manufactured arches were found     at some collapsed points and, also, extraction shafts were found in the overlying incoherent materials.}

Tufo. Extraction was either open-pit or underground. We refer you to the cited classic monograph by Dell’Erba. [trans. note: bibl. ref. 4 in title]

Tunnel [gallery] extraction is the method that is of immediate interest when discussing the subsoil. We note that in ancient times, the tunnels were dug such as to have a flat ceiling and two parabolic walls. The width of the ceiling was kept between 4 to 5 meters; the walls were 10 to 15 meters high, and there was a covered trench. Some examples that still exist are the Cristallini grottos, those along via Vecchia di Capodimonte, those between that road and via Nuova Capodimonte, the Gavoni [grotto] at Piazza Cavour, Piazza Dante, the Ventaglieri, and the Mangone quarry at Virgil’s Tomb. Others along the Porta-DueFontanelle axis were demolished when there was nothing left to extract. Between 1860 and 1870, that method fell into disuse in favor of a faster and more economic one, that of the curved arch. The shaft went in beneath a semi-elliptical or, rarely, semi-circular arch, and the walls were sharply accented parabolas.

These galleries were bigger than the earlier ones and could be as high as 22 meters plus the trench for waste rock. Cutting was done with a tool called a smarra, that is, a pick with two vertical blades at the points. Good results were obtained and the resulting blocks were about 25 centimeters on a side (until 1900 they were about 70 to one meter; the dimensions were then reduced such as to obtain about 100 to a meter).

The new method put hills at risk. Galleries crossed and intersected beneath them, leaving only slender supporting columns at the naves. The need for tuff increased, and gallery extraction continued. Some older galleries were demolished and others were indiscriminately expanded, such as at S. Rocco, Miano, Chiaiano, via Nuova Capodimonte, Connochia, S. Gennaro dei Poveri, Materdei, Fontanelle, Corso Vittorio Emanuele (Parker, Grotte Comola), Mergellina, Fuorigrotta, Posillipo and Pianura.

From 1935 to 1941, there was a crisis in the extraction trade. In the war years of 1941-43, cavities in the city center were used as air-raid shelters; at the same time, extraction continued in those cavities to expand the shelters, themselves. Besides newly dug galleries in the urban center at (Chiatamone, Mergellina), older and unused cisterns were put back into service.

The post-war chaos of 1944 saw this indiscriminate process of extracting tuff pick up again, denuding ancient underground cavities, thinning walls and support columns, and, worse, weakening the vaults. Underground cavities with flat ceilings that are of modest size and that have a 50% ratio of mined out void to remaining supporting pillars of tuff showed no signs of subsoil shifting or slides even 150 years after they were opened. That cannot be said of cavities with curved vaults and that are mined to a greater extent; they show a continuous degradation from separating ceilings and become more dangerous the longer they are open, now approaching 100 years for some of them. Another method of extraction was “bottle” or “bell” extraction, not used in Naples since 1920 but used in the area of Nolano as late as 1957.

The procedure was to sink a shaft, generally circular and uncovered, down to where the tuff started; then, down into the tuff for 4 or 5 meters (which layer would later have a load-bearing function). Then, the shaft was expanded out in a circular fashion to extract the commercial rock and reach the bed. Other similar shafts were sunk nearby, taking care to leave stable layers of support between them. At the bottom, the “bells” or “bottles” were then joined by horizontal shafts. When extraction was finished, the entrance wells would then be sealed by waste rock, in the neck of the bottle, leaving the mined void beneath it.

We have called attention to this method of extraction because there are a number of examples of it in the urban center: via Frullone, via Marianella, and via Chiaia (on the left past the bridge as you move down the street) where there are three wells with their respective “bells” that go from the gardens of the Military Tribunal on top of Monte di Dio almost down to street level. These excavations, thus, go back to a period before via Chiaia was laid as an offshoot of Pizzofalcone

This looting of the subsoil created such dangerous conditions, especially in areas of urban expansion and building on the surface, that state authorities put legal controls on what had been essentially unfettered speculation in the tuff industry. By decree, the High Commission of the Mining Bureau, on 23 April 1926, started to regulate tuff extraction in Naples. The regulation was based on an earlier law from 30 March 1893—i.e. law no. 184, that set up the Mining Police—and a subsequent executive order, no. 152 from 10 Jan 1907 (extended by G. di Stefano). After that, it was necessary to have a license for both open-air and underground extraction of tuff.

In the recent post-war [WWII] period, there was a frenzied hunt for building material. This led to tuff extraction that compromised much of the still green areas in the city (S. Rocco, Marianella, Chiaiano, Posillipo, Pianura). As a result, some single underground quarries were closed in the province and all such quarries were closed in the city ofNaples (drafted by D. Bardi). The regulations allowed only open-pit extraction and only the use of stone-cutting equipment that produced uniform blocks, thus reducing the amount of tuff that would have to be thrown out as waste rock. That was the beginning of the attempts to conserve the integrity of the subsoil beneath the city and, indeed, beneath the green areas that embellish the city.

As for the general situation concerning tuffaceous cavities in the urban center, we have concluded that those cavities with flat ceilings and vertical walls have not degraded over time. On the other hand, those with curved crowns, parabolic walls, and tenuous thinness at the tops, have, indeed, shown clear signs of movement and shifting. Slabs and chunks have chipped off and fallen from the surfaces; support pillars of insufficient thickness have been partially crushed and their bases have sunk into the beds of the cavities (the Chiatamone grotto, largo D. Morelli, the Parker Hotel, the Mergellina grotto, Comola, the grotto of Sermoneta, Posillipo).

Many of the cavities threatened by tuff slides or collapse have been reinforced by retaining walls, tuff columns, bricks, reinforced cement, etc. This has, in some measure, restored the strength of terrain disturbed by ill-advised mining. This has been done in a number of places, including parco del Pino on the Corso Vittorio Emanuele, the grotto at the Parker Hotel, the grotto beneath via Grazio, piazza Sermoneta, piazza S. Luigi a Posillipo, beneath some buildings at Chiatamone, Cappella Vecchia, etc.

images 39-40 (l&r) Cavity at #59 via        Montesanto, particulars  of the mouth        of a well shaft, used as is present-day        practice, disposing of trash and refuse.

Other cavities, however, have continued to degrade. Their support columns cannot take the weight; they are affected by irregular pressures and even external things such as water infiltration and temperature changes.

2) OLD WELLS, CONDUITS AND SEWERS

We mentioned the “bottle”-type excavation method in order to draw attention to the fact that parts of the city —along the Carmignano [aqueduct] and especially on the slopes of San Martino— are riddled with wells that are similar in construction.Within the city, wells were a source of water and were divided into two categories: passage/isolated; and well springs. We limit ourselves to the first category. These were located along the course of old aqueduct tunnelled waterways. When they were not actually a section of one of the retaining banks of a canal, itself, they were separated from the canal by a separating wall of tuff, one or two meters thick, through which ran a conduit that connected the well to the aqueduct. The second kind, the isolated ones, were on the right side of a canal and were the termination points of that canal. The water from one cistern could overflow into the next one with obvious risk of contamination.

A well has three main parts: the tub or cistern, the bell, and the shaft (see MELISURGO G. Napoli sotterranea, Naples, 1889). The tub is hollowed out of the tuff in the form a prism with a rectangular or square shape with the bottom of the excavation slightly concave or sloped to a particular point for ease of draining and cleaning. The bell is the empty space above the tub; the part of the empty space that corresponds and connects to the covering is more properly called the ciclo, the same name used for the shafts in underground tuff quarries. The ciclo space is shaped like a barrel, sail or tent with four bowed-out cylindrical surfaces. The shaft is the vertical part of the well that connects the tub and bell to the surface or to a building above where water could be drawn from various floors.

image 41

image 42

image43 41, 42, 43  shape and forms of the Carmignano aqueduct in the zone beneath via Pesisina.

The shaft of the well could be located centrally as in “bottle” or ”bell” extraction; it could also be off-center or on the side. Wells have also been found on the Poggioreale hill and in the Materdei section the city.^*2
*2. The wells in the Montecalvario section of the city were fed by the Carità canal, which drew its water from the Carmingnano aqueduct beneath the Palazzo Cavalcanti.

The above-mentioned canal, once it reached the spot beneath the corner between via Toledo and via Nunzio (today near Pasquale Scura) sent a branch off to the right to provide water to the wells of buildings to the east of Largo Carità and via S. Liborio as far as the Vacche Parish. The San Liborio steps are the beginning of Vico [small street] della Carità. After that, the main canal turns to the left and reaches a spot beneath Palazzo Cavalcanti, where it gets water from the upper Carmignano canal. After a short stretch, the canal forks; on the right, it forms the Peruso Nuovo branch and, on the left, the Tuvole branch. The former branches again at various points and provides water to the rest of the buildings on vico Carità, as well as to part of the following streets: Formale, v. Splendore, Magnocavallo (via F. Girardi), v. Trucco, v. Campanile, v. Grotta Mastrodatti, v. Consiglio, v. del Gelso, v. Speranzella, v. del Teatro Nuovo, v. Carità as far as [the church of] the Madonna della Grazie, v. Noce, v. Primo and Secondo Concezione Montecalvario, v. Primaportapiccola Montecalvario, part of via S. Maria Ognibene, v. Polito, and the steps of S. Maria del Monte, with the last well in the S. Pasquale convent.}

We repeat some of Melisurgo’s survey notes in order to show the kinds of shifting and movement in the subsoil that occur time and again beneath the buildings along via Formale in the direction of the church of Trinità degli Spagnoli. We note the remarkable sequence of calamities affecting the buildings on vico Noce del Calvario: 1861—Shifting and collapse of the wall on the east side, 5.90 meters from the building at vico Noce 20; 1890—a cave-in affecting buildings at vico Noce 14, 17 and 22 and via Prima Concezione 7; 1963—earth slides at vico Noce 17, 29 and 22; salita Magnocavallo (Girardi) 17 and via Prima Concezione Montecalvario 7.

Core samples done in 1963: vico Noce —a shaft of 28.60 meters reached 12 meters above mean sea-level [MSL]; a second one, 30 meters deep, reached 9 meters above MSL. The first sample passed through 5 meters of refuse, 2 meters of humus, and then a series of layered pozzolana, sand and alluvial pumice; the second sample found vegetable matter down to 7 meters and then the same alternating mixtures of incoherent terrain.

In the first two periods, various water wells were found that came from the old Carmignano della Carità partition. There were three beneath the building at via Nove 17, one beneath via Noce 20 and one beneath via Nove 20. The last one had a cistern hollowed out of the tuff and a square shaft partially carved into the rock and partially into incoherent materials supported by retaining walls. There was also a rain catchment cistern beneath the staircase at via Noce 22 and another in the building at via Prima Concezione 7.

The banks of earth and cappellaccio [loose, poor quality soil] beneath the foundations of the building at no. 17 rested on the vault that formed the ceiling of an underground cistern that was dug out only 40cm. into the tuff. The foundations, then, of these buildings —some with five stories— rested on incoherent terrain and were no deeper than 4 meters from street level. We note that the sub-foundation work done in 1861 and 1890 did not save the buildings from the cave-ins of 1963.

As we see from reports and our on-site investigations, the strip of land called the “Quartieri,” just a few meters above via Roma is affected by canals, cisterns and basins. The buildings in that area are generally taller than they should be, measured geo-technically, in terms of the resistance afforded by the land the rest on as well as by the strength of the buildings, themselves. If they have not been recently restored or shored up in some fashion, they are at the limits of their stability. We add to the information already given to us by De Stefano (see Chapter IV, part 2) on the presence of underground canals cut into the tuff: i.e. the position of ovoid sections along the minor (horizontal) axis Vi of the major (vertical) axis means that they can have no influence on the phenomenon of cave-ins, nor have we found in the cited literature any mention of that as a cause.

We can’t say the same for the cast-iron street conduits laid for the old Serino aqueduct; they were laid directly into shallow surface trenches. No reinforcement, shoring up or compaction of the loosely compacted soil was done when they were originally laid, nor have such measures been undertaken since, except in particularly dangerous spots.

Such measures could not be put in place at the time of the original installation for economic reasons and, more importantly, because of the urgent need at the time to have a supply of running water in the wake of the cholera epidemic (1884). The conduits of potable water in the older parts of the city are still suffering under the effects of this largely unchanged situation except in those cases where earth slides, the building of new roads, or general urban renewal have, in fact, led to the replacement of the older conduits with newer ones. Even modest pressure on the conduits can cause them to shift and start to leak, leading to erosion in the terrain that supports them as well as in the terrain around the tufo block foundations of nearby buildings. Many of these buildings are very tall, and the terrain that they rest on is compressible. The equilibrium of buildings in this situation is overtaxed and movements in the subsoil can assume alarming proportions.

The sewer system in the urban center is the subject of another part of this report, but we can say that the planning and construction of the system has been carried out efficiently. The base is a bed of hydraulic mortar (Vesuvian pozzolana and slaked lime) of a width never less than 45 cm. The sewage conduit is embedded in that mortar work such that leakage cannot occur except in cases of influence of external factors over a period of years and even decades. Even small factors, however, can cause voids around the conduit and eventually lead to breaks. That can lead to the subsidence of adjacent building and, in turn, can affect the road bed beneath the surface of the streets where thosebuildings are located.

All of these causes are interrelated and, themselves, made potentially worse by the possibility of cave-ins and slides in the terrain due to the number of cavities —some at considerable depth— in the subsoil.  p.117

image 44	image 45
image 46	image 47
Particulars of a huge water storage cistern; the walk-over bridges are carved from the surrounding tuff (45), cistern water flow control system at the union of the bridge-canal (44), water stains indicating various  water levels (46), small overflow channel for diverting water to an adjacent cistern (47)

END OF PART 2, CHAPTER 3

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START PART 2, CHAPTER 4

The great number of cavities (and their entrances) in the urban area makes it difficult to present an overall view of the subsoil of Naples. It is, thus, helpful to take a look at the various sections of the city and review the chronology of how these cavities have been excavated over time. We do that by examining the urban history of the city. We might then come up with a zone-by-zone picture of the urban subsoil that shows us where the excavations are most intense and where they present the most problems, which is, after all, the object of this entire report.

We can start by looking at figure 50, which presents the urban situation in Naples at the end of the 11th century. It is based on the well-known map published by B. Capasso in 1892,^*(1) which, however, limits itself to the area bounded by the old city walls. The map shows the areas of early Greek and Roman settlements located within the walls as well as some roads outside the walls that may be assumed to have existed at the time. We can thus see the connections to the west.

One such road runs through a valley corresponding to today’s via Chiaia, then along the beach to the cripta napolitana [trans note: the ancient Roman tunnel at Mergellina that goes through the Posillipo hill] and then left to the Posillipo coast. The other road, puteolana per colles, starts where one of the decumani [trans. note: east-west streets of the old city] ends, then by Spirito Santo and up via Salvator Rosa to run along the Vomero Hill to Antignano and then down the hill towards Agnano and the Campi Flegrei. ^*(2) As far as the connections to the north are concerned, we see the Capua road leave the city at Porta Capuana and the road to Nola leave at Porta Nolana.

*{1. Capasso, B. Topografia della Città di Napolinell’XI secolo. Naples 1895.}

*{2. Napoli, M. Napoli greco-romana, Naples 1959, p. 112 and p. 115.}

Another road must have connected Naples with the Vesuvius area (Herculaneum and Pompeii). These roads are amply attested to by archaeological and philological evidence, although there is some uncertainty as to their precise routes. Our goal is simply to present an approximate but fair indication of their presence. In tracing their routes, it was opportune to locate the various Greek and Roman tombs along those paths, knowing that they were situated immediately beyond the city walls and, thus, along the main lines of communication. We thus see the area of Neapolis, founded around 470 BC after the eclipse of the earlier Palepoli, which, under the name of Parthenope, grew up on the Pizzofalcone hill, approximately between 680 and 530 BC.

Clearly, the choice of where to build the settlement of Naples was closely linked to the morphology of the area. The site was surrounded on the east by a marsh, on the north and west by natural trenches that served as canals that gathered water from the surrounding hills, and, finally, on the south by the sea. Again, the city had canals as well as the sea and small hills such as Caponapoli, S. Giovanni Maggiore, Monterone, S. Marcellino, and Sant’Agostino alla Zecca. These natural conditions were such that the area could be easily defended by the simple addition of a city wall. From the period of its founding (470 BC) until 1140, the year that marked the end of the Duchy of Naples, the city wall underwent four expansions. ^*(3)

*{3. i.e. after the original wall from the 5th century BC, there followed another in the first half of the 4th century BC; and then in the 5th, 6th and 11th centuries AD.} In the 11th century, Naples had around 30-40,000 inhabitants, not having grown notably since Roman times. It had a relatively modest building density.

We attribute a first group of cavities to this period.^*(4) We note that there is evidence of digging in the subsoil of Naples from as long ago as 5,400 years. This is shown from the discovery in 1950 of two so-called “oven” tombs [trans. note: alias Chalcolithic and Copper Age] in the Materdei area. They were at a depth of about 6 meters “dug into the tuff wall of a slight slope and consisting of a small chamber with access by means of narrow corridor.” ^*(5)

48. Greco-Roman Naples (after B. Capasso)                                                                            49. XI Century Naples (after B. Capasso)

Among the most ancient excavations we also find the grottos at the foot of Mt. Echia, in the area of Santa Lucia and today’s via Chiatamone (the Platomonie grottos).(6) At the end of via Chiatamone we find the large cavity once held to be the Cave of Mithra; access is from the area behind the church of Santa Maria a Cappella Vecchia. There is another ancient grotto in the Posillipo hill with an entrance in at Piedigrotta near what is called “Virgil’s Tomb.” (7) This is actually a tunnel, 700 meters long, 4.50 m. wide, and 5 m. high on average. It is said to have been dug in the age of Augustus by the architect Lucius Cocceius Auctus and which even by the time of Seneca was dark and dusty. It was restored and enlarged numerous times by lowering the road bed. It was subject to cave-ins, especially after such lowering. It was finally abandoned in the 19th century.

Besides these, there is another tunnel in the Posillipo hill, built at the behest of Lucius Aelius Seianus, perhaps by the same architect, Cocceius Auctus. Also, the Posillipo hill was traversed by the Claudiusaqueduct,^*(8) from Roman times, built to carry water from the Serino aqueduct to villas at Posillipo and Bagnoli, and most importantly to the military naval center at Bacoli and Miseno.

We don’t have enough technical information to trace the path of this first aqueduct, but from extant descriptions, it must have been: Ponti Rossi, S. Eframo, the Botanical Gardens, and the Costantinopli Gate,forking there, perhaps to guarantee a water supply into the city. Then, it went to Gesù e Maria, S. Elmo, Vomero, and the ancient Pozzuoli grotto. From there, the main conduit went towards Mt. Olibano, Pozzuoli, Bacoli and Miseno, and a secondary line went towards the Posillipo point. In any event, it is certain that in these days of urban life, the inhabitants of Naples drew water from existing rivers (Sebeto and Robeolo) and from springs. It was not until later that they had access to the Bolla aqueduct.

Chiarini, in his comments on Celano, is of the opinion that the Claudius aqueduct must have co-existed with the Bolla aqueduct, the construction of which he attributes to the Romans, and perhaps eventhe Greeks. (This contradicts those who hold that the Bolla aqueduct did not exist until the 12th century.) Chiarini says that the Bolla aqueduct served the city by carrying water from the Volla plain (also Bolla and Polla) to the lower sections of the ancient Greco-Roman city.

To support his view, Chiarini points out that Naples, a city with water and public baths, existed before the construction of the Claudius aqueduct. Indeed, when Belisarius destroyed the Claudius aqueduct in 537 AD after using the conduit, itself, to get into the city, the citizenry really did not suffer at all since they still had access to water from the underground Bolla aqueduct.

Also, certain stretches of the Bolla aqueduct in the urban area have opus reticulatum brick work and marble covering.^*(9)

*{8. see Colonna, F. Scoperta di antichità in Napoli, 1898, from which p. 67: [ref to November 1882] “...during construction on the tunnel for the new Naples-Pozzuolisteam tram, an ancient aqueduct was found that could only be partially explored since it was not totally uncovered.” An accurate description follows.}

*{9. see Celano-Chiarini. Notizie del bello, dell’antico e del curioso della città di Napoli, vol. II (1870 edition) pp. 404 and following. Chiarini specifies that three stretches of the canal were carved completely out of a bank of tuff and that, furthermore, “...beneath the street dei Tribunali...” [trans. note: the central eastwest road of the ancient city] the canal was partially covered with “pieces of marble,” most notable of which included “...a white marble statue lying on its side with the knee visible and the folds of a gown, visible from the breast to the knee; also, a piece of a Corinthian cornice and the remains of a column. The other pieces were crumbled but might be from something on the opposite side and not visible.”}

Thus, it is plausible to hold that in the 11th century, a first part of the Bolla aqueduct was already in existence.

The other hill containing some of the most ancient cavities is the Capodimonte hill. We presume, it was there that they extracted the necessary tuff to build the Greco-Roman city wall, then movimg the tuff into place via the natural valleys of the Vergini and Sanità.^*(10)

There were also Christian cemeteries in the same area. There is a vast literature about them, but it is still an open question if these cemeteries were placed in cavities that already existed or if —in keeping with the burial traditions of ancient peoples— they were purposely built underground by Christians for their saints and martyrs and then later expanded in order to let the faithful be buried near the objects of their veneration. A number of catacombs came into existence in this fashion: S. Gennaro dei Poveri (3rd century), S. Vito or S. Maria della vita (2nd cent.), S. Gaudioso or S. Maria della Sanità (5th cent.), S. Severo (end of 4th and start of 5th cent.), and, in other areas, S. Eframo Vecchio (end of 3rd cent.), S. Maria del Pianto and the catacomb beneath S. Martino monastery. The main reason, however, for the excavation of cavities was to extract stone for construction (tuff, lapillo, pozzolana, etc.) ^*(11) which is why the increase in the number of cavities is directly proportional to thegrowth of the city.

Let’s look at a detail of the Lafrery map (fig. 53) now, some five centuries after the map was made (1566). It is the oldest map we have, drawn up when the places it represents existed, and it is considered a very reliable document. It shows in a “bird’s eye” perspective (not flat) the city and immediate environs beyond thewalls created by viceroy Don Pedro di Toledo between 1533 and 1574.

*{10. An interesting treatment of the excavation of tufo and other construction materials in Naples in the past is by G.B. Chiarini in his comments on Celano. See Celano-Chiarini, op. cit., vol. I (1870 edition) pp. 87 and following. Also see Carletti, N. La regione abbruciata della Campagna felice, Naples, 1787, p. 47.}

*{11. See Chapter III, part II of this report.}

*{12. Colonna, F. op cit, p. 13, contains the contract for the building of these walls. Among the stipulations are that the tuff for some portions of the wall was to mined from the Chiatamone hill.

After the Duchy of Naples, in the Norman period, there was no urban expansion of Naples. That had to wait for the Angevin period when Naples became the capital of the Kingdom. It was a time of development and urban renewal that saw the population increase from 40,000 to 60,000. When the Aragonese arrived in 1442, Naples reached a position of prominence from both an economic as well as an artistic point ofview. The beautiful tavola Strozzi [trans. note: an oil-on-wood painting of Naples from c. 1472] gives us an idea of the magnificence of the city during the Aragonese period. In 1484, work started on the new Aragonese walls to extend the city to the south, east and west. Many sections of those walls and towers can still be seen today. Within the city, at the same time, many smaller dwellings, numerous larger ones for the patrician class, as well as churches, convents and monasteries were built.

The work of urban expansion and renewal was then carried forward under the [Spanish] Vice-realm, primarily by Don Pedro de Toledo, who, as we have said, undertook to expand the city walls. This expansion of the walls, which would be the last, was the largest in the history of Naples. It was primarily of a military nature and was the first phase of a vast program to put order into the entire layout of the city by paving the principal existing roads and building new ones, includingvia di Chiaia. ^*(13)

Among the new roads, the most notable one was undoubtedly via Toledo (today, via Roma), built by Don Pedro along the old Aragonese trench from the Royal Palace to Porta Regia. Along this road, that is, at the foot of the Vomero hill, there arose an urban nucleus (indeed, called the “Spanish Quarters”) originally destined to garrison troops and then taken over by the civilian population. This was the period when many in the upper classes decided to move their dwellings to the new road closer to the Royal Palace, thus leaving their homes in theolder parts of the city, which were then rapidly and almost completelytaken over by the poorer classes. There was then a rapid decline in the urban fabric in this part of the city. It was caused largely by the chaotic increase in the construction of tall (and overly tall) structures and the building on spaces that had been open and green.^*(14)

*{13. The road was built between 1559 and 1634 to a plan by Domenico Fontana. It insured a better connection with the beach area of the city than the traditional longer route along Chiatamone and was less exposed to the sun and wind. See Celano, C., op. cit. vol. 5, pp. 562 and following.}

*{14. See Parrino, D. A. Teatro eroico e politico de governi dei vicerè del regno di Napoli, cited here from the 1875 edition, vol. I, p. 38 (the first edition is from 1692): “...The dwellings of the citizens are quite comfortable and tall; some are even six and seven stories. This is possbile because of the light weight of the stone and the fine quality of the sand, called Pozzolana, that, mixed with lime, makes a perfectmortar.”}

The possibilities offered by various life styles—even modest ones—,the presence of the vice-royal court and a large noble class as well as economic incentives all contributed to a notable increase in thenumber of persons coming into Naples, bringing the population to 212,000 in 1547.

New excavations were opened in order to meet the increasing demand for construction stone. This happened primarily on the Capodimonte hill, already cited, which provided easy access into the city along the Cristallini valley and the valleys of the Vergini and Sanità to the San Gennaro Gate and the oldest parts of the city. However, in order to serve, the zones of expansion to the west of the ancient walls and all the way to via Toledo, it was easier to extract stone from the area of S. Lucia al Monte and Ventaglieri, and then to use the easier access at the Medina Gate.^*(15)

The cavities to build the “Spanish Quarters” were opened on the eastern side of the hill, the part that runs from Petraio, then by S. Carlo to Mortelle and Pizzofalcone. This was the period when the technique of subsoil excavation finally developed such as to permit extracting materials on the site, itself,  of buildings that were going up. That technique was used primarily in the case of very large buildings such as churches and monasteries ^*(16) and a technique that then expanded greatly over the course of the next two centuries. In these centuries (i.e. the 1500s and 1600s) the city found itself in the absurd position of facing a growing population (to 500,000 in 1700) and, at the same, a series of “pragmatic” laws that opposed any building outside of the city walls. This was for military and economic reasons, but without any coherent economic policy.

*{15. The assault on the San Martino (Vomero) hill was so intense —at the end of the 16th century and beginning of the 17th— that viceroy Count di Miranda issued an official ban (20 May 1588); there was another such ban issued by Count di Lemos (9 Oct. 1615) in which all excavations were banned, whether to extract stone or to put up new buildings.}

*{16. For example, the monastery of S. Gregorio Armeno, those on the Pontecorvo slope and the Gerolamini monastery. See chapter 3 for a description of the “bell” or “bottle” excavation technique. Note also that Carletti (among others) writes (Topografia universale della città di Napoli, 1776, p. 9): [tuff] “...is used for building and is cut from beneath the present layout of the city and from the surrounding hills.”}

As a result, building within the city increased chaotically and unpredictably, and even spread outside the city walls in spite of the official bans on such construction. It spread along preexisting roads, wherever possible, but always without even the most elementary urban planning. Such a plan was even lacking in 1717, when a decree was issued that removed the building ban. [trans. note: That year marked the beginning of the 20-year Autrian vice-realm of Naples in the wake of the Wars of the Spanish Succession.]

The layout of Naples in the 18th century is given to us with great precision in the map drawn up by the Duke of Noja, Giovanni Carafa, finished by Niccolo Carletti, who published it in 1776 with comments and annotations.^*(17) The map shows the most important transformations of the city during the first 40 years of the Bourbon monarchy. This was when the city was once again the capital of a kingdom and enriched itself through important public works. The city walls and many city gates were demolished, construction was begun on the Royal palace at Capodimonte as well as the Foro Carolino and the Hospice for the Poor; streets were put in order and many new private dwellings added to the wealth of buildings in the city.

Obviously, a great amount of building material was needed to accommodate construction of the previous two centuries. The urban area was not much larger than what is shown in fig. 53 (i.e. more or less the same city area as in the 1500s). The material for all of that construction came basically from the same zones shown in fig. 56; that is, from the hills of Capodimonte and Vomero, from the sides facing the sea. Thus we have intense excavations in Vergini, Cristallini, Sanità, the S. Antonio slope up to Capodimonte and lower down almost to via Foria. New cavities were opened at Montesanto, Ventaglieri, at S. Antonio ai Monti and in the strip above the Spanish Quarters reaching up to about where the street, Corso Vittorio Emanuele, runs today.

The expansion of building along the Chiaia beach led to excavations on the western side of the hill of S. Carlo alle Mortelle as well as in the Mergellina area. At the same time, there was notable development in the techniques of excavating on site, that is, beneath the very spotwhere a new building was to rise. That method was so abused that in 1781 it was forbidden, and excavating beneath and inhabited area waspunishable by a three-year prison sentence, all in an attempt to stem the tide of cave-ins that were occurring. ^*(18)

*{17. Carletti, N. Topografia universale della città di Napoli in Campagna felice,
Naples, 1776. op. cit.}
*{18. That decree is contained in annals of the Tribunale di Fortificazioni of 3 Oct 1781. The text has been published by Strazzullo, F. Prammatiche per l’ediliza napoletana dal’500 al ‘700 in “Ingegneri” n. 36, 1966, p. 46 (capo IV)}

image 54  Plan by Stophendal (XVII century


image 55
Plan by Giovanni Carafa, Duke of Noja (XVIII century)

These often occurred because of the presence in the subsoil of the various conduits of the Bolla aqueduct, which had grown with the city. As we have said, with the population growth at the beginning of the 17th century, the need for water increased. Putting the old Claudius aqueduct back in service would have cost two million ducats, a financial impossibility. Thus, a plan was approved in 1627, a plan by the nobleman Cesare Carmigano and the mathematician, Alessandro Ciminelli, in which they offered, at their own expense, to bring water to Naples from the Faenza river. The work was completed in under two years in spite of great difficulties. On 29 May 1629, water entered the city and was channeled into the conduits beneath via Foria, via delle Pigne, the university and via Toledo, at first as far as the street at the Garrese Gate and then, after 1631, to via Conte di Mola.

In 1753, king Charles of Bourbon acquired the waters of the Pizzo river, a tributary of the Faenza, in order to supply the fountain-falls at the Caserta Palace. (The Faenza, as we have noted, fed the Carmignao aqueduct.) As a result, there was a drop in water supplied to the city. Thus, in 1770, as Carletti notes, king Ferdinand IV of Naples, decreed that water passing through the fountains at Caserta would then be channeled to Naples and into the Carmingnano conduit. That increased the supply but not enough to satisfy the entire population. Indeed, as Chiarini points out, that water flowed 26 mills on privateproperty, the millstones of 4 city-owned properties, 9 industrial factories, numerous private concessions, and 32 public fountains.

At first, the people, could at first only use the fountains fed by the Bolla aqueduct since those fed by the Carmignano were ornamental ^*(19) and only after some effort were they finally channeled into public wells. If we consider the amounts of water used by small urban industries (dye-works, tanneries, bath houses. etc. ) and water supplied to the many monasteries (“in abundance”), we see why many persons had only springs and public fountains for their water supply. Furthermore, the hill areas (Capodimonte, Vomero, Posillipo) had no aqueduct conduits at all and had to rely on the rainwater they could collect in reservoirs and cisterns. It was only in 1885 that the modern Serino aqueduct as built.

*{19. They were surrounded by gates to keep the populace from the water.}

Before looking at the situation in Naples at that later date, however, we consider the last stages of urban development and excavations in the final decades of the last century.

In the long period of Bourbon rule, public works were carried out that are still relevant today. These include the reordering of the area along via Costantinopoli and the construction of the important road, Corso Maria Teresa [trans. note: today’s Corso Vittorio Emanuele], which runs halfway up and along the Vomero hill for 5 km from Piedigrotta to the Cesarea [church]. We also note public works under the decade of French rule (1806-1815) during which time the road, Corso Napoleone, was built from the museum up to Capodimonte; also, the area around via Foria was reordered, via Posillipo was extended all the way to Coroglio, and the Botanical Gardens were built.

The Bourbon period corresponds to the beginnings of the industrial revolution and the first plants and factories as well as early railways and steamships. That substantial growth in public works, however, did not translate into any bettering in the economic or social lives of the ever increasing population. The people were crowded into old housing in terrible conditions of overcrowding and poverty. It was not until after the unification of Italy that attempts at planned urban renewal were made, which we see in in the early failed undertaking by the Banca Tibertina in the Vomero area. As well, we see the renewal of the Chiaia area, extending it towards the sea with the new road, via Caracciolo, and the expansion of the entire seaside area with new roads such as via Vittoria Colonna and Parco Margherita. Also, we see the expansion of the area of Vasto and the projects of the Risanamento corporation, such as the new Corso Umberto boulevard running between the train station and the stock exchange. These projects. however, did not bring any real benefits since they were isolated episodes and not part of an overall plan of urban development. In any event, such a vast complex of public works required additional excavations; these were, naturally, done outside of the urban area, which had and overtaken earlier excavation sites (fig. 60).

There are other cavities from the 19th century in the Capodimonte hill, and more to the north in the Scudillo area, in S. Rocco, the Fontanelle, and on the northern side of the Materdei and Vomero hills. A final increase is shown along Chiaia and along the path of Corso Maria Teresa, and there are a few totally isolated cavities at the summit of the Vomero hill. Finally, we note the construction between 1882 and 1885 of another excavation, 734 meters long, in the Posillipo hill. It showed severe cracks after just a few years; they could not be repaired and the site was abandoned. Another, smaller gallery was built next to it. It fared no better when an inappropriately slender tuff column was crushed, causing a collapse.

As early as 1855, the city deliberated on a tunnel to connect S. Francesco di Paola to Largo Cappella. It was started and suspended after progressing a distance of “1200 palms” [trans. note: about 300 meters.] It was only later, in 1927-29, that the Galleria della Vittoria was built. It was 624 meters long and connected via Cesareo Console with via Chiatamone.  Finally, we note the four cable-car tunnels: Central, Montesanto, Chiaia and Mergellina. The urban expansion of Naples from the end of the 1800s to today has been extremely intense. It was at first modest, disciplined and carried out in the areas we have mentioned (Vomero, Vasto, S. Lucia, theChiaia quarter) and beyond the Posillipo hill towards Fuorigrotta.

image 58	image 59	image 60
58. Entrance to Laziale tunnel at Piedigrotta            59. Entrance SEPSA rail tunnel at Montesanto               60. Entrance to galleria of Victory, via Acton   SEPSA (Società per l'Esercizio di Pubblici Servizi Anonima) was a public transport corporation that ran the two narrow gauge railways in Naples, the Cumana and the Circumvesuviana lines until it it was consolidated with other transport corporations in 2012. And the pressing question, in #60 the Victory Tunnel -- what Victory are are they talking about? You'll never guess. First correct answer wins a free ride on that train in #59.

After the ravages of war, however, the city underwent a rapid and intense expansion to meet the needs of a population that had grown to 1,200,000 persons. Unfortunately, there were no precise plans or appropriate building codes this time, either, and the expansion was disorderly and chaotic. As for the digging of new quarries for building material, they were ever farther from the urban center: along the Posillipo hill above the new road, and some in the areas of Colli Aminei, Scudillo, and the Cangiani Chapel. Large cavities and long conduits have been built since 1885 in order to provide reservoirs and conduits for the Serino aqueduct.

To the vast collection of cavities that we have indicated so far, we add the intricate web of conduits, large and small, that make up the sewer system ^*(20) and the ancient and modern aqueducts that we have mentioned. They run at various levels, often crossing and intersectingin the oldest parts of the city. We can postpone until chapters 5, 7 and 8 a more detailed discussion of the topic, but we point out that the illustration gives only an idea of the intricate complex of conduits and canals. To those we must also add the many wells that in the past served to provide spring water.^*(21)

*{20. From historical sources, we know that, in ancient times, the sewer consisted of a large canal, about 5.30 x 3.70 meters, that left from Piazza della Pignasecca. Carletti says: “this work, popularly called the ‘chiavicone’, winds along Toledo and picks up rain water at various points from the many streets and alleys that come down from Mt. Echia and Mt. Ermico to the Castel dell’Ovo, the Vittoria and the Chiaia beach.” Carletti, N. op. cit. p. 263.}

*{21. Lambertini writes (Lambertini, D. "Acquee sotterranee nel’ambito del centro urbano della città di Napoli" in Boll. della soc. natur in Napoli, vol. LXIX, 1960, p. 226): “In some cases, underground water rises and flows out on the surface in the form of true springs, known and used in the past, such as those that emptied along the beach line where it slopes towards the sea (Piazza Francese, S. Pietro Martire, Mergellina, S. Lucia, etc.) These springs, all of modest size, have disappeared today due to the changes in these area caused by construction...”  We can put off to chapter 5 the details having to do with water supply. We do note here, however, the thermals springs of Chiatamone and S. Lucia, where sources exist within Mt. Echia that still produce mineral water for drinking and hot water for therapeutic baths that for many years have been a commercial source of income. The wells marked on the map are listed in the appendix. For the schematic of the Bolla and Carnigano aqueducts, we have followed the description contained in Melisurgo, G: Napoli sotterranea, topograifica della rete di canali d’acqua profonda, Naples 1889.}

Having now followed the development of cavities in relation to urban growth, we can group these cavities by zone within the city.^*(22)

*{22. See table III in the attached atlas.}

They are:

    a) The area of the ancient historic center, bounded by via Roma until the National Museum, then via Foria, via         Cesare Rossaroll, S. Antonio Abate, via Pietro Colletta, the “Rettifilo” [Corso Umberto], and PiazzaCarità;

        b) Vergini and Sanità, the areas of the most intense excavation, extending from above via Foria to the Capodimonte         Palace and from the eastern slope of the Miradois hill to the western slope of the Materdei hill;

        c) the slope of the Vomero hill, above the street that runs from the Spirito Santo [church] by Piazza Dante to the             National Museum. Thezones included are Pontecorvo, Montesanto, Ventaglieri until beyondthe Corso Vittorio                     Emanuele;

        d) the eastern part of the Mortelle hill, above the “Spanish Quarters;

        e) below Mt. Echia in the low area formed by via Chaitamone, via S. Lucia and via Chiaia; ^*(23) [footnote 23 is                 missing]

        f) the western side of the Mortelle hill and part of the sloped of the Vomero hill that faces the sea;

        g) the northern area of Vomero, from Materdei to Scudillo;

        h) Posillipo (including the area covered by the SPEME convention) to Mergellina, the area in back of the railway                 station; there are here, as well, a limited —but well-known— number of grottos with entrances from street level as         well as, along the Posillipo coast, sea-grottos often used to store boats;

        i) the strip in the northern areas, outside the urban center, covering the areas from S. Rocco di Capodimonte, and             the Cangiani chapel to Chiaiano and Marano, that is, outside the Naples city limits.

Outside of these cavities in these areas, except in isolated cases, or something to do with the surface network of small pipes in the aqueducts or sewers, it is not probable there are other cavities that might affect the subsoil of Naples.

Our reasoning here has been to reduce the area where we have to find and identify cavities. Through that simplification, we may be able to wind up with a rational picture of the distribution of these tunnels and cavities and thus help solve two important problems: urban planning according to the “spessore” model and guaranteeing the stability of buildings. [translator's note: "spessore" means thickness. Essentially, worry about the large quarries first.]

      
END OF PART 2, CHAPTER 4      
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On the other hand, from the same figures, we see that where type A terrain appears, the depths at which usable groundwater is found is actually outside type A terrain and in type B but the aquifer remains usable whether it rests on tufo or is below it. Within the urban center, once the surfaces of the roof and base of the tuff is identified, those surfaces are assumed to be, respectively, the upper and lower surface limits of the zone, the former the surface limit and the latter the depth limit, in which we find usable water. Surface limits like that do not exist once we move to the eastern industrial area. As we see in figures 64 and 70, given that there is only type B terrain, the amount of usable groundwater varies from one vertical section to the next. Our conclusions differ considerably from those of Ruggiero [411] (1) and of others who have since relied on his conclusions.

Indeed, Ruggiero, who had much less data at his disposal than we have today, (see table V,) is of the opinion that in the urban center and industrial areas there are more distinct aquifers in the deep subsoil and that they vary from one to other according to a contour that he calls “eidipsometric”. (figures 71-73) [an English translation for “eidipsometric” is not readily found but as here used indicates a form of isometric data plotting] . More precisely, according to Ruggiero’sinterpretation, two of these aquifers —the second and third ones— are found in the subsoil of both the urban center and the industrial zone; the first one, however, is closer to the surface and found only in theindustrial zone.

From what have observed, however, the series of the eidipsometric curves furnished by Ruggioero refer only to the urban center and, by his own definition, refer only to the second aquifer. Indeed, as we see in figures 74 and 75, within the urban center those curves represent the contour of the surface at the base of the tuff mass and tell us that where type A terrain is on top of type B, we have to go below the tuff to find aquifers with a usable potential.

In effect, type B terrain occupies the entire well area in the eastern zone, and Ruggiero shows a scheme of distinct artesian aquifers moving through continuous strata of greater permeability that are among practically impermeable strata. Ruggiero’s scheme doesn’t seem to fit. It is more correct to use a scheme of a single phreatic aquifer [trans. note: “phreatic” refers to the violent activity produced by hot lava coming into contact with cold water] in which water moves through the heterogeneous mass and preferentially chooses a path through the materials that are more permeable and that are interlaced and chaotically mixed but in direct and continuous communication with one another.

For the same reasons, when type B terrain is below type A terrain, the aquifers are connected. Rather than viewing them as distinct and separate artesian aquifers, they should be considered a single one. Likewise, in some areas of the urban center, water circulates through type B terrain of varying degrees of thickness found both above andbelow type B terrain.This, too, should be viewed as a single phreatic aquifer. The many fractures in type A terrain, indeed, serve to stabilize communication between the phreatic aquifer in the overlying type B terrain and the artesian aquifer within the type B terrain below, such that it is not even necessary to make a distinction between the two.

That can seen from the fact that during various phases of drilling, all authors writing about this, with some rare exceptions, have noted that waters coming up separately from various depths have settled at thesame level.
That is to say, the aquifers along the same vertical section in undisturbed strata of different depths all have the same piezometric quotient, which is to say that they are connected. With that in mind, in discussing individual zones of the city andenvirons, we shall speak of a single aquifer and of surface levels within that single aquifer. More precisely, we shall refer to the level that water rises to from any depth in a well drilled at a given point in an undisturbed aquifer and define piezometric surfaces or surface levels in the aquifer as that surface that at all points has a quotient equal to the piezometric quotient in the vertical section passing through that point.

Beneath the surface level of the aquifer, the mass is saturated with water at all points. Above, it may still be saturated because of the thickness of the capillary fringe, and experience teaches us that the fringe may be some meters thick. In any case, by definition the surface level of the aquifer represents the isopiezic surface with pressure equal to the atmospheric pressure, and in the underlying mass the sinking of individual points below that will give the measure
in a water column of the neutral pressure at that point.

It is also helpful to remember that in situations where we may speak of a single phreatic aquifer, if there are wells nearby, and one of them extracts notable amounts of water from the aquifer, even depressing the level some meters, the water level in surrounding wells will not vary appreciably as long as they are a few tens of meters distant [385] [472]. This confirms what we said about how water moves in type B terrain. This also tells us that within a short distance from the point of extraction you can have notable variations in the level in the aquifer and in the distribution of neutral pressure in the subsoil, but only if the hydraulic equilibrium is disturbed by prolonged pumping and extraction of water from the aquifer in amounts substantially greater than the amount that flows into it from the basin that feeds it.

Before closing this brief premise, we call attention to the fact that in type A terrain above the surface level of an aquifer and above the overlying strip occupied by the capillary fringe, there can still be pockets or strata that are completely full of water. This can happen in a mass where the process of cementation of pyroclastic materials that originally formed the surrounding tuff has slowed or has not occurred at all [241] [338]. Also, since the tuff roof is a somewhat smoother copy of the primitive form of the terrain where it was deposited, such pockets or strata can also occur around the edges of the mass where there are openings that fill up with type B terrain and where surface water tends to infiltrate and accumulate [241] [384].

2) Our Data

    2-1) Early discussions of aquifers in the area include attempts by Celano, Carletti [77], Abate [6] [11] and Sasso [420]. From the presence of spring water on the eastern edge of the urban center of Naples they reconstructed the planimetric contour of the old Sebeto [river]. Those discussions were somewhat far-fetched. We note, however, that as early as 1843 Cangiano [62] [70], foresaw the possibility, (eventually only partially confirmed) — that the area might hold an abundant hydaulic stratum. That observation was on the basis of a simple geological inspection of the surface and the morphological characteristics of the area.

The stratum would be fed by the chain of calcareous mountains that run from near Caserta to Nola and the Sorrentine peninsula to form an amphitheater around the extended plain of the Terra di Lavoro [trans. note: archaic term for much of today’s Campania region] (Table IV). On the basis of Cangiano’s conclusions —and with Cangiano, himself, as
the driving force behind the project— two wells were drilled at the Royal Palace and at Piazza Vittoria. They were started in 1859 and reached, respectively, 456 and 281 meters. It was on the example of these first two wells that many others were then drilled in the urban center and environs at the end of the last century and beginning of
this one.

With the construction of these wells, we may well say that the firststeps were taken towards a more precise interpretation of the underground hydrography of the area. Indeed, at the end of the last century, there were attempts to interpret data from individual wells [267] [149] [347] as well as, by Palmieri's side-by-side comparisons of data from different wells and, finally, by Cesare [96] in the first essay on the underground hydrography of the area of Vesuvius to the immediate east of the city. There were also attempts during this same period to trace the origins of the waters on the basis of their chemical composition [84] [85].

Another notable step towards understanding the underground hydrography of the urban center and surrounding area was taken in the last twenty years of the 1900s first by engineer Contarino [114] and then D’Amelio [144]. They measured the water level in a substantial number of wells within the urban center and came up with a fair approximation of the contour of the surface level of the aquifer in 1884. Those were Contarino’s first measurements, of about 180 wells. His second measurements of about 130 wells were in 1889-90 . Also, D’Amelio’s made measurements on about 100 wells) in 1900-01.

As a result, we now know about the levels in the aquifer within the urban center; they may be seen from the curve in Table 5. Then, from D’Amelio’s 1901 measurement, it was also possible to gauge the seasonal variations that the aquifer undergoes throughout the year as well as the mean variations between 1884 and 1889-90, immediately after the Serino aqueduct went into service, and in the following decade, between 1890 and 1901 (see fig. 76-79). There is less information on the levels in the aquifer at the end of the last century in the western part of the city. What we have comes from studies done at the time by the Municipal Technical Office to trace the Cuma effluent. [463].

All in all, whatever the results, we can say that by the end of the 1800s we knew what steps we would have to take to have a more exact knowledge of the hydrography of the subsoil of the city:
We would need accurate and systematic measurement of underground water levels and levels in the aquifer; we would have to reconstruct the geology of the area using stratigraphy from wells and core samples in addition to surface inspection; and we would have to determine the chemical composition and compare waters extracted from the aquifer in various zones and at various depths.


2-2) Studies were undertaken, if not always methodically, in the years before WWII. Thus, in 1926, Fiorelli [206] took accurate measurements of the water levels reached at various times during the year within the many
phreatic wells dug for irrigation in the eastern parts of the city

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