Naples:life,death &
                Miracle contact: Jeff Matthews

entry Jan. 2011

he Roman Aqueduct (item 1, directly below); the Serino and Benevento Aqueducts (item 2, also below)
         (item 3, below: Part 2, Chapter 7 of The Subsoil of Naples,   Part 2 Chapter 8    to Ch. 9 - to different page
                                                                       (7. the aqueduct)                (8. the sewer system)

The first two items appeared separately in the original version of the Around Naples Encyclopedia on the dates indicated and have been consolidated here.

entry Mar. 2003
aqueduct, Roman

For those who are not claustrophobic —nay, for those who absolutely revel in their agoraphobia— I recommend a visit to the Roman aqueduct system that supplied Naples. It is one of the most impressive feats of engineering undertaken in Naples during the reign of Caesar Augustus. The aqueduct was 170 km long and started at a reservoir fed by the river Serino (see map in item #2, below). There were two branches: one led to Beneventum and the other to Neapolis. The one to Naples approached the city from the slopes of Capodimonte, then went on to Vomero and to Posillipo, the hill bounding the western end of the city. From Posillipo, a secondary branch lead through the hill and to Fuorigrotta and beyond, to Puteoli, modern day Pozzuoli. Parts of the aqueduct were open and others were tunnels through the rock. 

That Posillipo aqueduct runs parallel to the Roman tunnel known as the Seiano Grotto and was apparently built at the same time as the tunnel, itself. The tunnel is occasionally open for visits. As far as I know, the aqueduct is not; I know of its existence only because I was led into it by a crazy archaeologist friend of mine. It was there that I found out that I don't particularly like to be cooped up in tight spaces beneath mountains. 

In the city of Naples, itself, the water distribution was by a system of subterranean conduits leading from the main aqueduct. More recently, during the aerial bombardment of WW II, the ancient aqueduct was put to use as an air-raid shelter, the wells and cisterns being enlarged to allow for the passage of people. There are underground tours available of the section of the aqueduct directly below the historic center of the city. The aqueduct is appropriately dark, deep, and scary. Visitors are even issued candles to light their descent. It is also very, very cold, which makes it the perfect place to visit in July and August. The entrance is from Piazza Gaetano near the intersection of via dei Tribunali and via San Gregorio Armeno. (At #33 on the map of the historic center of the city. Click here.)

entry April 2007
2.  the Serino and Benevento Aqueducts

Passing Water in Naples

There, now that I have your attention, this is about aqueducts.

Very early: Naples is a very old and continuously inhabited center of large population and, as such, has always required a generous supply of fresh water. The earliest documented conduit to supply the ancient city is the so-called Bolla aqueduct. An 1889 study entitled Topography of the deep water network of canals, contributing to the study of the subsoil of Naples by Gugliermo Melisurgo, claims, however, that "… there remains some mystery as to its origins". It may have been Roman or, even earlier —Greek. So, briefly, we don't know. If there were Etruscan or even Samnite aqueducts in the area, we don't know that, either. Suffice it to say that the Bolla was an important aqueduct in the ancient city and, in spite of being superseded by later ones, remained important, seeing service as late as 1947 (!).

The Romans: It is not evident from looking at the western end of the Gulf of Naples—that is, the Bay of Pozzuoli—that this is where the "beautiful people" lived at the time of Augustus Caesar. After all, who wants a house in downtown Naples if you have the money to move out near the mythological roots of the whole gulf, where Ulysses and Aeneas trod, an area replete with splendid thermal springs and offshore islands. At the same time, the area contained Puteoli (Pozzuoli), an important commercial port; also, nearby Cape Miseno sheltered one of the best natural harbors on the west coast of Italy, a perfect place for an imperial fleet.

The Serino and Benevento aqueducts (in green) including
the Avello aqueduct for Pompeii (dotted green line).
aqueduct map

(Map © Cees Passchier. Acknowledgment below.)

The Roman aqueduct to supply the idle rich, the merchants and the imperial sailors with water was extensive and, indeed, an impressive feat of engineering. The Romans brought water into the area via the Aqua Augusta, historically referred to as the Serino aqueduct. The source was in the Terminio-Tuoro mountains and was named the Fons Augusteus, now known as Acquaro-Pelosi, near the town of Santa Lucia di Serino, due east of Naples, not far from Avellino.

The Piscina mirabilis            

                  mirabilisAlong its 100 km length to service Miseno, the aqueduct also passed by Pompeii, Herculaneum and Naples, with numerous branches from the main aqueduct running in to provide water to the public and private fountains and cisterns in those communities. In Naples, the Serino line passed through a tunnel now known as the "Crypta Napoletana," one of the Roman tunnels that passed beneath the Posillipo hill to lead to the Campi Flegrei, the town of Puteoli and then the target at Miseno, the largest freshwater cistern ever built by the Romans, the Piscina Mirabilis (photo, right).  The cistern was dug entirely out of the tuff cliff face and was 15 meters high/deep (ca. 45 feet), 72 meters long (ca. 220 feet), and 25 meters wide (ca.75 feet). The capacity/volume was 12,000 cubic meters (ca. 36,000 cubic feet). It was supported by vaulted ceilings and 48 pillars. Adjacent to the main cistern at Miseno were a number of other private cisterns such as the one now called the Cento Camarelle— the One Hundred Little Rooms— a group of cisterns arranged on two levels, possibly the property of the orator Quintus Hortensius Ortalus.

Modern Times: The ancient aqueducts served the city and surrounding area until the Spanish vicerealm, when the Carmignano aqueduct was finished in 1629. It was named for  Cesare Carmingnano, a nobleman who engineered the feat. It seems to have incorporated a preexisting conduit that sources say "may have been Roman."

After the unification of Italy and in the wake of severe hygienic problems in Naples, including outbreaks of cholera, the decision was made to build a new aqueduct. It was built between 1881-1885 and was a vital part of the "Risanamento" — the massive urban renewal of the city between 1880 and 1915. The agency that administers the modern Naples aqueduct is called ARIN, an acronym for Azienda risorse idriche Napoli (Agency for Water Resources, Naples).

The aqueduct is named the Serino, the same name as the ancient Roman one. There are actually two groups of headwaters in the area that are utilized by ARIN: the Acquaro-Pelosi at 380 meters above sea level and the Urciuoli at 330 m. The ARIN facility that collects the water and starts it on its journey is set on about 50 acres.

From the 60 meter long Serino canal that brought the water out from the source, the aqueduct then included more than 20 bridges along the route to Naples, the longest of which was 1800 meters. The aqueduct then ran through a large distribution point in Cancello di Caserta and made a 22 km run into the two large municipal cisterns, one at Capodimonte (capacity: 82,000 cubic meters) and the other at Scudillo (capacity: originally 20,000 m3, then increased to 145,000 m3). The 1885 finished aqueduct was meant to serve the needs of the population of the city at that time—about 500,000. With the 1936 expansion, the current capacity permitted a flow of as high as 2350 liters per second (between 500-600 gallons).

Today, the aqueduct systems have been upgraded to supply the increasing needs of the city and the northeastern part of the Campania region. There are now four main lines that supply water from sources in Lazio, Molise and Campania. Besides the 1885 aqueduct, there now exist the Campania aqueduct (1958), the Western Campania aqueduct (1998) and the Lufrano Aqueduct (ongoing upgrade). Of historic interest is the post-WW2 resurrection of the ancient Roman Bolla aqueduct to help supply the city during the drought of 1946-7.

Interestingly, the 1967 work cited below contains this: "...[supply]...will increase with the completion of the Campano aqueduct to about 350 liters per person per day...for a population of 1,425,000, predicted by the year 2000...the calculations run through to the year 2020 and aim at a sufficient water supply for the predicted population of 1,650,000."

That is way off; the current (2010) population of Naples is only about 1,000,000).

I gratefully acknowledge the following sources for this article:

The map of the Serino aqueduct remains the copyrighted property of Cees Passchier and is used here with his kind permission;
The Other City by Antonio Piedimonte (an English translation by Larry Ray is available on his website) ;
The website of NapoliUnderground (NUg) (with special thanks to Clemente Espositio and Fulvio Salvi for their generosity and the above photo of the Piscina mirabilis. The NUg website is now off-line, which is why it is not linked.
--(1967) Il Sottosuolo di Napoli [The Subsoil of Naples], published by the city of Naples (available in Italian and English on the NUG website, directly above.]
An excellent article on the Serino aqueduct (one of a series by Wilke Schram) on his website;
The website of ARIN, the Naples Water Management Board.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Oct 27, 2019 -- this is Part 2, Chapter 7 followed by Chapter 8 of Il Sottosuolo di Napoli [The Subsoil of Naples], (see the list of sources directly above). That book is no longer available on the original hosting website. It is off-line. jm


The Subsoil of Naples, Part 2, Chapter 7

The Aqueduct and the Subsoil
under the direction of Dr. Eng. Silvio Terracciano

A) General technical premise
The aqueduct is one of these public services that live at different depths in the subsoil of the city. The intimate relationship between systems of the aqueduct and the nature of the subsoil is evident. On the basis of that relationship, criteria are established for planning and carrying out various kinds of projects *(1) bearing in mind two fundamentals: 1) the kind of structure and 2) the materials and methods of construction.
Number 1 can be divided into: (1.1) conduits, (1.2) canals, and (1.3) reservoirs.
Number 2 can be divided into (2.1) metals, (2.2) cements or lapideous
materials, and (2.3) excavation in rock or natural terrain.
*[1. By “projects” we mean everything that is part of an aqueduct, such as conduits,canals, reservoirs, etc.]
Generally speaking, two different kinds of projects go into building an aqueduct: adduction, that which conveys water from the source (natural springs, aquifer, lakes, river, sea, etc.) to the city, and distribution, that which distributes the water to consumers. In our case, we are referring to the distribution of water and connectimg to the subsoil of Naples.
B) Carrying out the projects

Referring back to section (A), we note that heading 1.1 (conduits) implies, generally, work at shallow depth along the path to be followed since, as we know, conduits are under pressure. Conduits can be at any altitude (as long as they don’t cut across the piezometric level); and depths, for safety reasons and because of water temperatures, are generally around 1.5 meters. Heading 1.2 (canals) implies a given limit at the point of departure that may be only slightly varied so as to avoid an excessively rapid flow of water (inclines between 0.5% and 1 % are permitted). Heading 1.3 (reservoirs) implies various positions in respect to the path to be followed since you can have elevated reservoirs, those that are partially underground and even those buried at great depth. As far as 1.2 and 1.3 are concerned, the nature of the subsoil determines, sometimes decisively, the path and position of the aqueduct.
As far 2.1 (metals) is concerned, we note that conduits are mostly of steel or cast-iron.*(2)
*{2. Lead is used only for waster or thermal waters and is never laid beneath ground.}
The choice is a function of the physical and chemical characteristics of the subsoil. In the presence of stable terrains, cast-iron is preferred, while in unstable terrains, steel is used, which, however, must be properly protected. We have not yet had satisfactory experience with plastics.
For heading 2.2 (cements or lapideous materials), we observe that, in general, it is possible to use these materials to build large-bore conduits (which is also convenient economically), and shafts to hold the conduits, canals and cisterns. Here, again, the nature of the subsoil determines, depending on exactly what you are building, which materials to use. For 2.3 (excavation in rock or natural terrain), canals and cisterns, ona case by case basis, may be either partially buried and made impermeable or constructed entirely underground.

C) Historical notes on the aqueduct of Naples

In past centuries, providing Naples with water was done through aseries of remarkable projects that always took advantage of the subsoil of the city. The first aqueduct was the Roman one, called Claudius,*(3) which, with a
course of about 80 km, brought the waters of the Serino to Naples, Pozzuoli and as far as Bacoli, where the Piscina Mirabilis is still preserved today.
*(3. In Campania, there also the Campano and the Augustus, which provided water to, respectively, Cuma and Literno, and to Venafro.)

The aqueduct entered the city as a free surface open channel via the “Ponti Rossi” [red bridges] (altitude of the bed, 42.10 m.]; the rest was in tuffaceous rock, which permitted a series of branches.
The Trinità ex-monastery there is a large cistern with the bed set at about 15 meters below the surface of today’s vico Paradiso. When the Claudius aqueduct was destroyed around the 6th century, water supply in the city was handled by local wells and many smaller springs, such as “Tre Cannoli,” “Acqua Aquilia,” “Santa Lucia” (not the same as the current sulfur spring), the “Leone” [Lion] at Mergellina (still in existence today, with its source behind the building at the corner between via Mergellina and via Grazio), “San Paolo” and so forth.

Another ancient aqueduct was the “Volla” or “Bolla,” providing phreatic waters near the town of “Casa dell’Acqua” in the area of Casalnuovo. About 10 km long, this aqueduct (with the aqueduct bed at 14 m. a.s.l.) brought water to the Poggioreale zone and the lower zone of the city. In 1629, a Neapolitan, Cesare Carmignano, built a canal, at his own expense, to bring waters of the Isclero, near the town of S. Agata dei Goti, to Naples. By means of an extensive net of channels or formali, the system provided water to the buildings of the city.
All buildings in the old part of the city had wells to draw water from the Carmignano via “well pipes,” which with time were walled over and served as cisterns. The subsoil of the old city is, thus, criss-crossed by this series of channels. Later, the presence of tuff led to a new distribution scheme in the subsoil that even today, in terms of efficiency and perfection has no equal in other cities.

D) Position of components of the aqueduct

We consider now the various components that make up the actual aqueduct that distributes water in Naples, divided by types that are of interest to us.
a) Reservoirs: The most important are the Scudillo and the Capodimonte (image, right), with respective capacities of 145,000 m3 and 83,000m3. Not counting later expansions, they were built in 1885. They are dug entirely in tuff, and the surfaces of the basins are covered with a layer of plaster. They are of excellent quality both from the standpoint of technical perfection and the special construction made possible by the compactness of the tuff rock.
Other reservoirs dug into the tuff are S. Stefano, with a capacity of 12,000 m3 (in the area of Corso Europa) and Chiaiano, with a capacity of 16,000 m3 located in the town of the same name, still the site of tuff quarries. Underground reservoirs, set however into reinforced cement, are S. Giacomo with a capacity of 60,000 m3, S. Rocco with 80,000 m3, and Vomero medio with 3,600 m3. Partially underground reservoirs are Cangiarli with 10,000 m3 and Camaldoli with 1,200 m3.

b) Canals: Arenella, which is part of the primitive network from the 1800s, connects the Scudillo reservoir to the pumping station of Vomero a San Gennaro. The canal is 2,008 meters long and, walled with tuff, is embedded in various kinds of terrain. At the point ofdeparture, the bed is at 176.95 m. above sea level and at 176.03 at the terminus.
Large artery: one of recent construction solved the problem of supplying the western part of the city. It leaves the Capodimonte reservoir and runs to the end of the hill at via Manzoni, to a spot called “Cupa S. Giovanni.” It is 5,813 meters long; at departure, the bed is at 91.37 m. above sea level and at terminus, 90.00 m.
c) Conduits: the conduits of the network are mostly of cast-iron and steel; some, generally adduction lines, are of reinforced cement. Generally, the conduits are not set lower than two meters below the surface. In order to lay large-bore pipes, abandoned quarry spaces have occasionally been used (for example, the cavities at Reichlin at Capodimonte). Some conduits that serve important streets (via Roma, via Duomo, via Chiaia, Corso Umberto, etc.) have been set in shafts in order to avoid damage to the roads in case of leakage and to avoid blocking traffic during maintenance. In some cases with reclaimed land, the conduits are also set in shafts (the streets of the Speme quarter, the Traiano quarter, etc.).
The special configuration of the Neapolitan subsoil has always demanded the utmost attention from those responsible for the aqueduct in order to avoid breaks, which, as we have seen on various occasions, can have serious consequences.

E) How the nature of the subsoil affects the aqueduct of Naples

We have said repeatedly that the planning and construction of the aqueduct and its components have in large part been favorably conditioned by the nature of the subsoil of Naples; however, it is also true that this same nature has often had negative effects (that we don’t find in other cities) in the operation and maintenance of the aqueduct. The conduits are the manufactured components that suffer the most from the nature of the Neapolitan subsoil, while canals and reservoirs are generally not affected since they are in tuffaceous rock at a considerable depth.
Any water leak in the subsoil, even the smallest, is absorbed into the incoherent loose terrains (often disturbed, i.e. the result of having been moved into place) producing empty pockets, some quite large. The loose material then often flows into underlying cavities, creating conditions that can then lead to a later break in the conduit which, with the escape of water under pressure, aggravates the phenomenon and produces enormous damage and sometimes the collapse of entire buildings (to wit: via Stella, Salita Trinità degli Spagnoli, etc.) The zones in the city that have been most affected by this phenomena are:
—the [Spanish] Quarters above via Roma; —Materdei;  —Stella;  —S. Antonio Abate.
The nature of the subsoil, particularly untrustworthy, is aggravated by the conditions of the public sewers, and even more so by private ones. Secondary sewage lines in factories, for example, are almost always in poor condition because they are very old or not maintained properly. Added to that is the fact the streets that until just a few years ago bore only pedestrian or very light vehicular traffic now bear intense traffic from vehicles of all sizes. The collapses and caves in the areas indicated above were occurring with such alarming frequency that the Aqueduct Authority had to moved a large section of the underground network (in cast-iron and not far below ground) to the surface. Another incidental effect of the Neapolitan subsoil upon aqueduct components stems from the presence of “well pipes,” mentioned previously. Buildings in the old city were, indeed, fed by cast-iron conduits that, after branching off from the main trunk beneath the public street and passing beneath the courtyard of a private building, rose vertically to the upper part of the well pipe (which long ago, as we have said, descended to the cistern fed by the Carmignano aqueduct.

image 107 (left) - Reichlin quarry, used for laying a water conduit-
image 108 (center - Capodimonte reservoir access tunnel.
image 109 -Capodimonte reservoir (right) -  storage tank excavated from tuff (250m long, 10m high)

Well pipes were later walled in, and when courtyards were then subjected to heavy vehicular traffic, water leaks increased, leading to considerable damage. Under those conditions, damages to the pipes beneath the courtyard and to the vertical pipes were noticed only well after serious consequences had already occurred, consequences that would have been  much less if the various components had been positioned normally.
Even here measures were taken to eliminate the underground stretches and move them to the surface in iron pipes. Unfortunately, those areas of the city, where the subsoil is the most dangerous in terms of operating the aqueduct, are precisely the older zones, where the only metal available at the time the conduits were laid was cast-iron. This material, as is known, does not hold up well under flexing or cutting; thus, the slightest give and drop in the ground below where the conduits are laid can lead to breaks. These problems with the subsoil have thus led to noteworthy problems in operating the aqueduct. We can't avoid these problems if we don't know the true nature of the subsoil.
images 110 (left) -111 (right) layout of water mains (800 mm diam.) running through the  ex-Reichlin quarry.

F) Action to be taken in working with subsoil

As noted, in the most dangerous zones, the Aqueduct Authority has tried to ensure the integrity of its installations by
—substituting most of the cast-iron conduits with steel or by moving them to the surface;
—creating, where possible, distribution boxes for the sewer systems;
General steps  have been taken to regulate new canalization. They deal with the use of materials that best fit the subsoil and with setting up distribution boxes for the sewage system. The basic problem, however, is in how to avoid empirical ad hoc fixes. We need to approach problems systematically according to two basic criteria:
—create, wherever possible, utility service tunnels;
—use the subsoil spaces such that one service does not interfere with and damage another.*(4)

*{4. see Messina, U.: "Problemi particolari della costruzione delle reti di distribuzione di acqua in pressione." Rivista ingegneri, no. 38, year VII, and see norme DIN – 1998 – 2425 – 4050.}

For those operations we obviously need a precise knowledge of the nature and condition of the subsoil. More precisely, we need a map for all agencies that provide public services (first and foremost, the Aqueduct Authority simply because of the consequences of water leaks), a map they can use to pin down the work they have do on a case-by-case basis.

left -  Capodimonte reservoir: storage tank access.

The above-mentioned construction of shafts, besides eliminating the inconveniences caused by leakage and breaks, will make it easier to modify, expand, and maintain the entire system without having to tear up roads with all the inconvenience that entails. A study is indispensable of all the city streets in order to pinpoint work that has to be done by AMAN [the Aqueduct Authority]. For new roads, we have to find the most economic solutions to our problems. The present commission has been charged with finding solutions that do that and that go beyond the typical case-by-case solutions.

right- Tunnel dug into tuff) for distribution of water mains, 800mm and 600mm .

End of Part 2, Chapter 7

 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

This is chapter 8, on the sewer system.
Before you start, there is a much less technical version of this chapter here. It was my summary of this chapter some years ago.  (I left out all the talk about money!) jm.

The Subsoil of Naples
Chapter 8
The City Sewer System—Defects & Remedies
under the direction of Dr. Guido Mortone

The main components of the sewer system within the city limits of Naples (before the incorporation of S. Giovanni a Teduccio, Barra,Ponticelli, S. Pietro a Patierno, Secondigliano, Chiaiano and Uniti,
Soccavo and Pianura, incorporated by the royal decree of 15 November 1925, no. 2183, and of 3 June 1926, no. 1002) are still those built in the wake of the cholera epidemic of 1884. The new system was set up by the executive decree of 1888, approved by the Upper Council of Public Works in 1889 and begun immediately afterwards. The work was almost completely finished in 1915.

Before that, there were studies between 1873 and 1883 authorized by the city administration, which was concerned over the extremely precarious conditions of public hygiene in the city. In those days, the city was served by a mixed network of sewer lines totaling 180 km in length with 54 collectors set along the watershed
line or point of maximum slope, from which sewage was channeled down to the sea.*(1)
*{1. A map layout of that network, mapped in 1875 on a scale of 1:1,000, is in the State Archives.}
The basic criteria for the [new] project were the following:

1) Free the city shoreline from sewage and channel it into single collection line that would start at Piedigrotta and empty at the shoreline below Mt. Cuma;
2) Channel rainwater into the waters along the urban shoreline via a new system of channels as well as along ancient river beds in the low areas of the city;
3) Permit the channeling of waste mixed with rainwater along the urban shoreline only in cases of intense rainfall, greater than 20mm/hr. [trans. note: somewhat less than 1 inch/hr.];
4) Regulate rain run-off in the hill areas.

A single large sewer line (named the Emissario di Cuma [Cuma Effluent]) was planned and built from the extreme west of the urban center to the exit point at Mt. Cuma. The path of the affluent network [i.e. collection network] was chosen such as to fit the layout of the city and, for economic reasons, to utilize the greatest possible number of preexisting sewers along the way. Land in the city was thus divided into three zones: high, middle, and low. Along the lines of demarcation of each of these, just below those lines, a collector was built to serve the respective zone above —that is, to collect affluent and channel it down. The point at which all such points of the affluent network converged was in the extreme western part of the city, called Piedigrotta, within the tuffaceous mass of the Posillipo hill.

The topography of the city, however, made it impossible to set collectors for the middle and low areas such that waste would simply “gravity flow” to the collector for the Cuma effluent. Pumps were thus installed, limited, for reasons of economy, to use only in dry weather. For this purpose, sewers in those areas were planned and built to have two canals, one for run-off and one for waste. Particularly, the middle zone had a divided system of two separately walled canals, one above the other; the low zone also had a divided system, but with one canal for rain run-off and the canal for waste mounted high within it, almost at street level.

Rain run-off from both the low and middle areas of the city were destined for the urban shoreline by way of a collector on via Guglielmo Sanfelice at the level of via Medina with the outlet at the port at Piazza Duca degli Abruzzi. The upper (run-off) canal of the collector for the middle zone of the city (the collector for via Medina to Piedigrotta) had the effluent canal below it; it exited at Coroglio near the area of “Seno della Badessa.” It also took run-off from the collector for the high zone of the city. The old collectors were used to feed run-off into the new collectors.

Two collectors were provided for the purpose of keeping turbid rain run-off from the hill areas out of the collectors and sewers in the rest of the city. One was the called the “eastern hill collector”; it emptied into a preexisting rain canal at Fontanelle, itself a tributary of the Arenacela canal, which flowed into the sea at the port near Ponte della Maddalena. The other was the “western hill collector”; it emptied into the sea at largo Sermoneta in Posillipo.

Obviously, those projects were conceived with reference to the total urban situation from before 1888, which the attached plans showing the relative routes also refer to. Waste load was calculated on the basis of a mean population density of 600 persons per hectare and a mean daily consumption per person of 50 liters with a point coefficient equal to 4. Run-off load was calculated, for the large basins in the north, with a coefficient of total reduction equal to 0.50 and a rainfall of 50mm/hr and 90mm/hr. for the medium and small basins. The dimensions and characteristics of the manufactured components of the relative sections are shown in the attached graphics.

 images above, 115-118 and below, 119-120: working drawings of
 collectors from the 1889 project 
(Naples archives, vico Maiorani)

The above-mentioned work was done with funds as provided for by the Law for the Risanamento of Naples [trans. note: literally, “making healthy again”—it was the massive “urban renewal” project from the end of 1800s and into the 1900s] voted on and passed by the parliament on 5 May 1885.

We observe the following in regard to the 1889 project:
    —the criteria of functionality, i.e. data on the new urban sewer system, the choice of the exit at the Cuma            Effluent, and the structure and routes of the main arteries are all still valid today;
    —on the other hand, the criteria for calculating the amounts of time for water to accumulate, and the actual        volume of water, in rain basins were too make-shift. These factors are important in calculating how water is         then fed into a system; equally inadequate were flow coefficients set on the basis of the project, itself;
    —finally, separating
waste and rain waters into the middle and low areas of the city is outmoded.

Mishaps that might arise are evident: pipes, often insufficient, that are meant to channel liquid waste, break easily, and workers often break pipes to clear an obstruction. As a result, a channel that was meant to carry only rainwater down to the sea turns into a mixed sewer line. Even in the dual-channel lines, the separation between the upper (rain) channel and the lower (waste) channel is never perfect. Indeed, maintenance of the lower channel often damages the seals on the small observation ports, particularly on bends. Rain and mud can thus spill into the lower channel and cause an overload at the pumping station. That, in turn, causes wear on the centrifugal pumps due to dirt and sand in the water that has to be pumped upwards and also causes clogging in the collecting basins of the station itself. Furthermore, it is almost impossible to detect through the observation ports the presence of possible corrosion on the walls of the pipes; corrosion can cause leaks, which can then cause shifting in the soil and cave-ins at neighboring buildings.

images 121 & 122 (above): more working drawings from 1889 - the caption on the left reads "new sewer type
using pipes of the 'system separator' type. The caption on the right is self-explanatory.

The new system was started in 1889 and finished in 1915, after which point a number of noteworthy expansions were made. They were necessary because of local urban development as well as the incorporation of the eight adjoining towns, mentioned above, to the city of Naples. The expansions to the system were made without modifying the scheme of the original project.

The original project, for reasons cited above, was not really a well-coordinated overall plan. It led to gradual deficiencies over much of the network. The main error was a helter-skelter expansion to try to cover the quarters of Posillipo and Mergellina, Vomero-Arenella and Materdei, as well as the new sections of Camaldoli, Capodimonte, Miano, Mianella, Piscinola, and Marianella, and the formerly separate towns of Secondigliano and S. Pietro a Patierno. The basin was four times larger than the one provided for in the original project. Furthermore, the progressive decrease in the urban area of green areas and the increase in impermeability of newly paved areas changed the conditions of flow to the sewers that served the older parts of the city even if the affluent basins remained the same. We have indicated on the map, (above, fig 123,) at a scale of 1:25,000 the routes of the main waste water collectors and indicated with different colors the work done before 1915 and that done afterwards.)

image: 124
Full discharge from the Capodimonte
aqueduct into the rainwater collector in

       the eastern section of the upper hills

In 1949, the city administration, concerned with the situation, commissioned engineering professor, Castone de Martino, to do a large-scale study with the goal of adjusting the urban sewer system.

The study was done zone by zone in all the urban territory, and the proposals were as follows:
    High zone:
    —Resize the high collectors and adjust the main ones;
    —Construction or re-construction of the skimmers on all emissions at the High Collector in order to ensure the appropriate distribution of mixed waste between the high collectors and the drainage channels;
    —Branch the high collectors into the dry weather tributary sewers that run into the drain channels.
    —Adjust the drain channels and build a new one at via Duomo.
    —Adjust the entire network of rain channels, both artificial and natural, with the termini at the Fontanelle            river-bed, Vallone S. Rocco, and the Regi Lagni.
    —Build a new collector for the eastern area with a link from Vallone S. Rocco as well as from the Naples and        Volla reclaimed land area with subsequent lightening of the loads on urban collectors.
    —Adjust waters in the wooded areas on the hill slopes in back of the city and at Vallone S. Rocco.
    —Adjust waters in the wooded areas on the hill slopes in back of via delle Puglie.

    Middle zone:
        —Adjust and modify the current network by using existing channels.

    Eastern low zone:
        —Adjust and modify the current network by using existing channels and construction of a new sewer                   collector for the new via Marittima and pumping waste water directly to the High collector;
        —Integral construction of the waste network for the zone bounded by via Stadera, via Poggioreale, and via            Arenaccia and in the industrial zone with the terminus at the new treatment facility in S. Giovanni a                    Teduccio.

    Outlying zones:
        —New construction of a waste collector for the low Posillipo area and pumping affluent from the Posillipo                high collector directly to the Cuma Effluent;
        —Using the High Posillipo mixed collector only for waste to be conveyed directly to the Cuma Effluent and            construction of a completely new run-off network by using existing natural strainers;
        —Construction of a completely new waste network for the Agnano area and semi-pump to the Cuma                    Effluent;
        —Adjust the water situation in the wooded area of the Arena S. Antonio basin;
        —Completely new “separator”-type sewer system in the sections of S. Giovanni a Teduccio, Barra and                    Ponticelli, and construction the relative treatment facility;
        —Completely new “separator”-type sewer system in the sections of Soccavo and Pianura;
        —Modify the separator system in the existing mixed sewage lines in the sections of Miano, Mianella,                    Piscinola, and Marianella.

The funds for the new work were provided through the first Special Law for Naples from the Cassa per il Mezzogiorno [Fund for the South]. On March 1, 1955, the City Council commissioned a study to determine exactly how the money should be spent. The study was under the direction of engineer Mario Folinea, honorary president of the High Council for Public Works The study was finished on 4 October 1957. The budget was outlined as follows:

High zone

1) Resizing the High collector: L. 125,000,000
2) Drainage channel at via Duomo: L. 355,000,000
3) Adjust main collectors (Calata Capodichino, Corso Umberto a Secondigliano,Capodimonte, Vomero,                    Arenella): L 1,000,000,000
4) Adjust old eastern and western collectors to move dry-weather waste and first run-offsto the High collector:         L. 415,000,000

Middle zone:

5) Adust fecal network: L 1,500,000,000

Low zone:

6) West—Change to mixed system with pumps and transport directly to the HighCollector. L. 1,661,000,000
7) East—Building of new sewer and pumps for Nuova via Marittima. L. 600,000,000
8) id. Adjust waste network. L. 1,350,000,000
9) East—Construction of fecal collectors for area bound by via Stadera, via Poggioreale,and via Arenaccia and         nearby industrial zone and join to the zone served by the treatment facility at S. Giovanni a Teduccio.
        L. 4,500,000,000
10) id. Adjust run-off collectors in the industrial zone. L. 2,000,000,000

Outlying areas
11) New collector for Lower Posillipo. L. 500,000,000
12) Adjust Upper Posillipo. L. 350,000,000
13) Adjust Campi Flegrei sewers (Fuorigrotta, Banoli). L. 200,000,000
14) Sewers in Agnano, with pumps. L. 150,000,000
15) Sewers, Piano and Soccavo, both waste and run-off. L. 610,000,000
16) Sewers, Chiaiano and Uniti. L. 200,900,000
17) Adjust sewers in Miano, Mianella,Piscinoloa, Marianella. L. 570,000,000
18) Sewers in Barra, Ponticelli and S. Giovanni di Teduccio
    a) waste and run-off L. 1,720,000,000
    b) treatment plant L. 600,000.000
    c) components at shorelinefor the above. L. 240,000,000

Regulating rain run-off from the hill areas
19) Arena S. Antonio basin L. 700,000,000
20) Levante collector and adjust relative basin. L. 4,000,000,000
21) Basin collectors for the Fontanelle riverbed. L. 1,000,000,000

Sub-total: L. 24,346,900,000

22) unforeseen items (c. 12%) L. 2,976,000.000

Total: L. 22,322,900,000

[trans. note: That figure in Italian lira (L.) equaled about 36 million US dollars in the early 1950s, when this project was funded. Comparative purchasing power is more complicated to calculate, but most indices indicate that 36 million $US in the early 1950s equals very roughly at least 300 million $US in today’s terms, i.e. 2010, (the first translation). For this new translation from 2019 and because I know that you won't look it up for yourselves, I did your homework for you. I called a Nobel prize winner in economics. He said, "OK...carry the 2 ... wait ... got it. Uh, still about 10 times. Say, what's a guy like you doing with that kind of money? What's your address?"]

Lift plant system (Villa Comunale) for sewerage as well as
rainwater runoff in the lower eastern zone; in 128, electronic central control center
for Mergellina, Villa Comunale, and Victoria tunnel. In 129, machine room; in 130,
intake suction tanks; in 131, circular rotating separation tank.

On the basis of the above study, the following items have been completed as of this writing:

1) with the funds provided by the 1st Special Law for Naples, no. 297, of 9 May 1953, the total of L. 4,953,400,000 for adjusting and updating the river-bed of Vergini and Arenaccia, the main run-off arteries of the urban network, and furnishing with dynamic sewers the sections of Chiaiano, Secondigliano (Berlingieri quarter) and parts of the sections of Ponticelli, Barra, S. Giovanni a Teduccio, Soccavo, Pianura, and partially adjust the existing network in the sections in Miano, Mianella, Piscinola, and Marianella;

2) with funds from the Cassa [del Mezzogiorno], a total of L.2,815,000,000, with the share of L. 715,000,000 assumed by the city in accordance with Law 589 of 3 August 1949, for the hygienic renewal of the shoreline from Porto Militare to Mergellina; and for the sum of L.3,140,822,125, with the share of L.723,959,500 assumed by the city, for the 3rd round of construction on the dynamic network for the sections of S. Giovanni a Teduccio, Barra, and Ponticelli, and for completion of both waste and run-off lines in the sections of Soccavo and Pianura. Total: 5,955,822,125;

3) from ordinary municipal funds, works for a total of L. 354,500,000 for the resizing of the collector at Calata Capodichino, for adjusting the western collector to move light waste and first rainfall to the High collector, and for the partial adjustment of the High Posillipo collector. Currently underway with ordinary municipal funds totaling L.379,000,000 for the doubling of the S. Pietro a Patierno collector and for lightening the load on the Viale Colli Aminei collector.

The new Special Law for Naples foresees the following:

1) Works by the city for L. 7,250,000,000

a) Resize the main Ponticelli waste collectors along road 167. L.140,000,000;
    —b) New waste collectors along state road 7 (alternate) with terminus at the Cassano collector to serve the             Secondigliano community along road 167;
        L. 150,000,000:
    —c) Waste sewage network to serve those areas of Agnano not already provided for;
        L. 350,000,000;
    —d) New separator-type sewers with divided channels along those parts of via Pigna not yet provided for;             L. 270,000,000;
    —e) New separator-type sewers with divided channels to replace the obsolete mixed channels at via
           Chiaiano-Marianella and adjusting the pluvial river-bed above.
        L. 97,000,000;
    —f) Final work on the river-bed Finanzieri road with construction of sewers and appropriate shafts for existing           water conduits on that river-bed as well as branch lines to handle the run-off of the collectors at via                   Ribera and via Francanzano,                
    —g) Branch lines for run-off at the via Regina Margherita collector to the new eastern rain collector,
        L. 33,000,000
    —h) Work to resize the first two trunks of the High Collector from via Foria to via Roma at the corner of                 Maddalon, that is, the skimmer windows of the Ventaglieri-Pignasecca drainage channel, also foreseen as         part of the planned expansion of the basin served in the zone of Secondigliano, and the regularization of             the number of skimmers at the collectors as well as the main emissions to insure the prescribed degree of         dilution at the drainage channel of1:5 for waste,                      
        L. 230,000,000;
    —i) New eastern collectors for run-off along road 167 in Secondigliano and of that part of 167 shared by                 Ponticelli above via Argine that are not served by existing pluvial collectors; also, collectors to handle the             load along the S. Rocco river-bed, the main tributary of the Arenacela river bed, the waters of the north-            eastern urban area that now flow into the Taglia basin, owned by Cardilo, as well as thewaters of the                 Pioggioreale and Capodichino hills that flow into the run-off network at via Stadera and via Poggioreale,             tributary of the land reclamation canals of Naples and Volla.
        L. 5,750,000,000
Total: L. 7,250,000,000

2) Plan and build under the auspices of the Cassa per il Mezzogiorno for a total of L. 7,250,000,000:

A) To adjust and integrate waste and run-off sewers in the current industrial zone and east, precisely:
1) Build local channels above via Stradera and via Poggioreale to catch run-off from the hills of Poggioreale and the Capodichino Airport as well as the other hills above via Stradera and movingthose waters to the new eastern run-off collector planned by the Sewers Division of the city of Naples.
2) Appropriate work to hold solid materials at the head of the covered channels that exist along the rainwater basins of the Poggioreale and Capodimonte hills and move the respective entrances upwards away from the urban periphery.
3) Secondary waste network as a tributary of the new waste collector of via Stradera and via Traccia (which Cassa del Mezzogiorno project is still under review by the Special Delegation of the High Council of Public Works)
Predicted cost: L.1,000,000,000
B) Hygienic renewal of the port waters in the lower east zone in front of Piazza Municipio and via Marina di Gigli, precisely:

1) Building waste pumps for the new collector at via Marittima.

2) Pumps for the collectors at via Reggia di Portici and via Ponte della Maddalena.

Predicted cost: L.500,000,000

C) Adjusting waste network in the eastern urban zone that flows to the collector at New via Marittima and the collectors at via Reggia di Portici and via Ponte della Maddalena.

Predicted cost: L.750,000,000

D) Adjusting main collectors that flow to the High collector, precisely:
1) Work to lighten the run-off load of the Middle collector in the stretch below Piazza Plebiscito intended to drain the entire load of the Cloaca Massima by existing skimmers at that piazza, subject to the clearing of a restricted section of the Cloaca Massima
Adjusting the eastern collector at via Gussone
to carry dry-weather and first rainfall loads to the High Collector at Piazza Carlo III.
Adusting the Montella Collector in Vomero in the section along via A. Falcone and the private area below  it as far as the point where it meets the High Collector at via S. Maria la Neve.
4) Work to reroute the run-off load of the via Tasso collector to the Laganà and M. Cristina di Savoia strainers, tributaries of the western hill collector, and relative subsequent work.
5) Work to reroute the run-off load of the Arenella
collector to the eastern hill collector.
6) Work to resize the Cassano mixed collector
to accommodate new waste influx from Secondigliano, according to law 167.
Predicted cost: L. 900,000,000

Total: L. 2,750,000,000

Furthermore, projects to be completed in the near future with Cassa del Mezzogiorno funding at the personal behest of the Assessor for Public Works, the Honorable Minister Pastore:
    1) Work to complete both waste and run-off networks for the sections of S. Giovanni, Barra, and Ponticelli             (approved by the High Council of Public Works (vote no. 163).
        cost: L. 1,780,000,000
    2) Work to complete both waste and run-off networks for the sections of Miano, Mianella, (approved by the             High Council of Public Works (vote no. 261 and already contracted).
        cost: L. 900,000,000
    3) Work for the new waste collector at via Stadera and Poggioreale and via Traccia (under review by High         Council of Public Works).
        cost: L. 2,000,000,000
    4) Construction of the terminus trunk of the new run-off effluent for the section of Pianura via the Italsider         plant in Bagnoli(approved by the High Council of Public Works(vote no. 259 and already contracted).
        cost: L. 400,000,000
    5) Work to complete the sewage treatment plant at for the north-east (in progress).
        cost: L. 490,000,000

    Total: L. 5,580,000,000

Ordinary municipal funds have been set aside for the following items:
    1) Run-off sewer viale Kennedy and worksto complete the Piscicelli channel.
        cost: L. 80,000,000
    2) Auxilliary Coroglio effluent.
        cost: L. 250,000,000
    3) Collectors at via Miano-Agnano Pietravalle trunk and the separator to servethe new university hospital.
        cost: L. 160,000,000
    4) Modernize and upgrade the waste pumps at via L. Cattolico and via Acton.
        cost: L. 200,000,000
    5) New sewer collector at via Tasso.
        cost: L. 800,000,000

Total: L. 1,490,000,000

To complete the entire sewer system project, the following work still has to be done. Funds are not yet available.
    1) Rebuild the old collectors at MianoCapodimonte, Corso Umberto a Secondigliano, Cacciottoli, Conte della             Cerra, Salvator Rosa, via Salute, via Paolo Emilio Imbriani, CorsoVittorio Emanuele, and Cloaca Massima at         via Roma.
    est. cost: L. 1,500,000,000
2) In many urban zones (Vasto, Vicaria, San Lorenzo, San Giuseppe, Vomero, Fuorigrotta) the sewer network is dual channel; the lower one is semi-elliptical andis for waste water, and the upper, larger-borechannel is for rain run-off. The two channels are separated by a horizontal diaphragm and haveobservation ports in them mounted not less thanfive meters apart. It is almost impossible to detect corrosion through these ports until it is too late, and the corrosion has already led to significant leakage into the subsoil and subsequent shifting in the soil below street surfaces and nearby buildings. The only way to prevent this is to build a system in which waste conduits are completely independent of run-off conduits.
  We estimate the cost of such a project, very roughly, at about:
L. 10,000,000,000

3) Regulate run-off from the hill areas:
    —S. Antonio basin L. 1,000,000,000
    —new Levante basin collector L. 1,500,000,000
    —Fontanelle river-bed basin L. 500,000,000
    —S. Rocco river-bed basin L. 500,000,000

4) Adjust and integrate run-off sewers in the industrial and eastern urban zones.
est. cost: L. 2,000,000,000
5) Adjust the High Posillipo network.
est. cost: L. 500,000,000
6) New collector for Lower Posillipo.
est. cost: L. 750,000,000
7) New waste sewers and adjust therun-off sewers in the basin the flows to S. Rocco S. Croce a Miano.
est. cost: L. 500,000,000

Rough total: L. 18,600,000,000

We emphasize that for the sewer system in the outlying urban areas, which had had no earlier system at all, and in the INA-Casa and CEP communities, criteria of the earlier 1889 project were not used; local hydraulic calculations and studies were used. Little preventivemaintenance can be accomplished in the channels in those areas. We recognize in those areas at least the need for access shafts forunderground conduits that have to be worked on. This will help to stopwater from leaking into the ground where the conduits are laid, which leads to eventual breaks in the line with all the problems that entails. We recommend extending these access maintenance shafts along all main roads in the area that don’t already have them. We estimate that
that will cost about L. 5,000,000,000.

The above proposal is absolutely essential to the overall adjustment of the sewer system of Naples.

Rainfall data

The 1889 project cited rainfall statistics from the CapodimonteObservatory and the University for the 11 years from 1873-1883. In one year, there was on average:
10mm/hr of rain—22 times
20mm/hr of rain—8 "
30mm/hr of rain—2 "
40mm/hr of rain—0.82 "
50mm/hr of rain—0.54 "
60mm/hr of rain—0.36 "
Normal rainfall was considered to be 5mm/hr; strong rainfall was5mm-30mm/hr; more than 30mm/hr was very heavy. [trans. note: 25mm is about 1 inch.] Using a coefficient of 0.50 to calculate load on the channels with
respect to rainfall on the affluent basins, it was calculated that the channels should be able to handle rainfall of 20mm/hr. [thus, 4/5 of one inch/hr] For anything greater than that, only part of it would go into the collectors; the rest would go directly into the sea.

Prof. De Martino, in his comprehensive study of the sewerage system of Naples, pointed out that there were 14 meteorological stations that measured rainfall, 9 of which were equipped with recording devices; in spite of that, the collected data had not been organized such as to furnish a good idea of rainfall over time; yet, he did find the following:
    a) data on intense rainfall at all stations for 1921-1940, in the hydrographic annals;
    b) data on intense rainfall measured at the Capodimonte Observatorystation for the period of 1880-1930;
    c) data measured at the Institute for Geophysics of the uniersity ofNaples and carried in the report "Pioggia di         massima intensitàprevedibili per Napoli" [Predicatable intense rain in Naples] by engineer Andreotti in the         Annals of Public Works, March 1930.

Bearing in mind that the longest distance traveled by rainwater from the farthest point in the sewers to the effluent is 10 km and supposing a speed to one meter per second, it follows that full capacity will be reached in not more than 3 hours. Prof. De Martino calculated that for rainfall lasting up to three hours, the equation h=0.065 T' best corresponds to the conditions of Naples. He noted that from 1883 to 1950, only two exceptional episodes of rain did not fit the equation: 17 August 1917 (Capodimonte Observatory) and 6 June 1918 (Institute of Geophysics). The commission saw fit to adopt Prof. De Martono's proposal as a variable correlation of rainfall intensity.

Current and future water facilities

The current water supply of the city of Naples is provided principally by the Serino aqueduct, which, after picking up influx from the Acquaroand Pelosi springs, conveys most of the flow to Naples. The capacity of the Serino cannot be increased. Secondary sources are the Bollaaqueduct and the Lufrano wells. The capacity of the latter can be modestly increased. The Serino provides about 175,000 cubic meters per day; from that, about 60,000 m3/day are destined for other communities served by the same aqueduct, leaving Naples with 115,000 m3/day.

The Bolla aqueduct and Lufrano wells provide about 150,000 m3/day; thus totaling 265,000 m3/day. To that we add the amount provided by the Campano aqueduct, about 85,000 m3/day, for a total of 350,000 m3/day. That provides the current population of 1,100,000 inhabitants with about 300 liters of water per person per day. That capacity will increase with the completion of the Campano aqueduct to about 350 liters per person per day (including the amounts provided by existing aqueducts) for a population of 1,425,000, predicted by the year 2000.

As we shall see, the calculations run through to the year 2020 and aim at a sufficient water supply for the predicted population of 1,650,000. The Commission calculates that supply of 350 liters per person per day will hold for that target year of 2020. This includes water also required for waste removal. [trans. note: The 2010 population of Naples was only about 1 million as opposed to the 1967 prediction of about 1,500,000.]

Demographic situation

In the years from 1812 to 1891, the population of Naples (center and villages) went from 326,000 to 522,595 inhabitants; that is, anincrease in 80 years of 196,595 inhabitants. The improved hygienic conditions due to the construction of the Serino aqueduct and the new sewer system (built between 1889 and 1915) as well as the phenomenon of urbanism all brought about in the next 57 years (i.e., until 1948) a population increase in the center and villages of 316,356 inhabitants. Other circumstances than natural demographic growth, however, led to an abrupt increase in the years after 1925. The Royal Decrees of 15 November 1925, (no. 2183) andof 3 June 1926, (no. 1002) incorporated the following towns in the city of Naples: Barra, Ponticelli, S. Giovanni a Teduccio and S. Pietro aPatierno, as well as Secondigliano, Chiaiano and Uniti, Soccavo and Pianura.

Those incorporations increased the population (census of 1931) by116.639 inhabitants, a number that increased by natural demographic growth to 158,312 in 1948. That brought the total population of Naples to 997,263.

Prof. De Martino's report, cited above, reports census statistics from 1812 to 1948. He deduces that if we want to calculate future population of natural exponential laws according to the equation N=Noxan where No is the current population and N is the future population after n anni [years], the resulting demographic increase would be 8.4% for the years 1921-36, 10.4% for the years 1936-48,and, finally, 9.3% for the entire period of 1921-48. Prof. De Martino extrapolated his predictions for the years 1950-2000. His own figures gave him a population for Naples of between 1,540,000 and 1,708.000 for the year 2000. He considered those numbers to be too high and came up with the lower figure of 1,425,000 inhabitants for the year 2000. That corresponds to a mean increase of 6.8%, a figure that corresponds to the one used in the planning of the Campano aqueduct. [note from 2019: again, due to "urbanism" -- people driving their own private vehicles out of the city instead of into it -- those number are dramatically wrong. They are way too high.]

The Commission generally agreed with the numbers for the year 2000 but decided to extrapolate out to the year 2020 in order to calculate whether or not the existing collectors (the Cuma Effluent, the Coroglio Drain, the High Collector, the Middle Collector) would meet the needs of the entire city. The longer extrapolation was necessary because we have learned from experience how complicated it can be to build systems such as this to meet growing needs. Considering the technical requirements, the finances, and the time lag from plan to finished product, we added another 20 years in order to be on the safe side.*(2)
*{2. Remember that the first studies on building a new sewer system for the city of Naples were done in 1873 and the work was finished in 1915—and not even entirely.}
With that in mind, the commission used the 1951 population of 1,027,800 inhabitants and extrapolated on the basis of a growth rate of 6.8% per thousand to predict the population for the year 2020:

N= 1,027,800 x 1.068 = 1,650,000 in e.t.


waste water

Calculations of waste water were based on demographic data from the zones to be served with, as we have said, a target of 350 liters per person per day for the period 2000-2020, assuming a further increase
in the capacity of the Campano aqueduct. We assume that 80% of distributed water load will reach the sewers and that the point of maximum load at the principal collectors is equal to 1.30 of the mean.

It follows that the maximum load on a collector that has to serve N inhabitants will be:

350 x 0.80
P.max = N x 1.30 = N x 0.004

Run-off load

Calculations for run-off load are based on the probable maximum amount of rain in areas served by given collectors by application of the equation h = 0.065 T°'333 and on the basis of the coefficient of flow set for various zones based on final destination as stipulated in the buildings codes; taking progressive urban development (construction) into account, terrain that now absorbs will become more or less impermeable, obviously in relation of the greater or lesser amount of buildings. Assuming the stipulated destinations, we have adopted the following coefficients of flow:
    urban center under intense construction ф = 0.90.
    residential zone under intense construction ф = 0.80.
    residential zone under semi-intense construction ф = 0.70.
    residential zone under extensive construction ф = 0.60.
    zones of isolated constr., industrial zone ф = 0.40-0.50
    Green areas ф = 0.30.

Load determination

For each trunk of a collector, we have determined the area of the basin served, A, and, thus, the reduced area,
фA. We measured the length,l, from the beginning of the section under scrutiny and assigned another length, l', to denote both the surface path as well as the path in the secondary sewer line from the most distant point in the basin tothe collector.

Assuming a mean velocity, V, (less than that presumed in a full collector) of between 0.60 and 1.20 m/s, variable with the slope of the basin, we assume a time of t = 1+1'/V for critical duration of rainfall and deduce the maximum value, i, to correspond to that duration. The expression Q = ix фA/3,600 m3/s gives the maximum load that a collector can be designed to handle.

If there are full drains along the collector, on the trunk below it we repeat the load calculation as if it were an initial trunk and add the load that the skimmer lets through. Obviously, in the course of the development of these projects, first calculations such as the ones above have to be constantly revalued and modified.

Hydrometric data of the sewers

In order to examine how existing collectors might be used within the new system, we constructed a velocity and load scale for each one of them using Bazin's formula with a coefficient Y = 0.18. The primary network of the Naples sewerage system in existence at the time of this study as well as the proposed expansions and
modifications are indicated on the attached plan at a scale of 1:25,000.

That map is from 1957. We see how alterations were made after that date to the natural rain catchment basins in the extensive wooded areas of S. Giacomo dei Capri, Sgambati, Camaldolilli, the Pigna tributary of the reclaimed river-bed of Arena S. Antonio. The intense construction in those areas, which are areas that flow to the Montella collector, explains the serious phenomena that have been occurring for some years at the collector and its Laganàoverflow drain (via Aniello Falcone, via Tasso, Corso Vitt. Emanuele, via S. Maria la Neve).

An analogous situation is found in the vast wooded area above and below via Colli Aminei that flow into natural catchment basins, tributaries, respectively, of the San Rocco valley and the Scudillocanal. Those areas have been transformed by intense construction. The natural run-off flows to the collector at the via Colli Aminei collector and serious phenomena have occurred at various points along the road bed situated above. As far as that last collector is concerned, there are works in progress to lighten the flow; as well, work on the Montella collector and Laganàoverflow drain has already received financing.

The municipal sewerage office has unfortunately been subjected to some changes and restrictions that have hindered its ability to manage the network. Originally, it was the "Special Office" to supervise public and private
sewers and was an adjunct of the Sewerage Inspection Department of the General Directorate of Public Health. In 1915, it was changed into the Sewerage Section of the Municipal Technical Office. Later, in 1939, with the reform of municipal offices —reforms that are still in effect— it was disbanded and its functions were distributed among the other sections of the Technical Office, some of which were not even in thesame division of that office.

For example, sewerage maintenance was handled by the Roads Section of the 2nd Division, and pump maintenance was under the technological section of the 4th Division. That absurd situation came to an end in 1944 through a de facto reestablishment of the sewerage section within the 2nd Division for Roads.
It wasn't until much later, in 1963, that the office was configured in keeping with the important and delicate nature of the task at hand. It became a Division unto itself, divided into three sections: the first was for research and planning; the second for supervision and maintenance of the network (and development of it to about 780 km in length); the third was for supervision and maintenance of pumps.

Personnel, both workers and supervisors, have always been too few for the job. They are responsible for a very important and complex set of tasks, and they are overworked and underpaid.

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