Roman Construction and Infrastructure Part 3: Water Infrastructure 4.0 Roman Water Infrastructure The Roman water infrastructure consisted of four main areas, water conduction, drainage of lands, canals, and harbors. The area which will be given the most attention is that of water conduction, however, the other three areas are also very interesting. The Roman system for water conduction, at it's peak at around 300 AD, consisted of 11 aqueducts. These 11 aqueducts supplied the city with approximately 1,168,850 cubic meters of water per day. This is an astounding number compared to today's standards, averaging out to about 200 gallons per person per day. 4.1 Roman Land Reclamation Efforts Long before the Roman's had a need to bring in water from outside sources, they had a need to remove water from their city. One of the first efforts to improve drainage came in 500 BC when Tarquinus Superbus, seventh king of Rome, straightened and widened a brook which emptied into the Tiber. This canal known as the Cloaca Maximus was also navigable by small boats. Over time it became used as a depository for waste and turned into a foul smelling open sewer. Later it was roofed over and became a sewer of exceptional capacity. Today it carries somewhere around one million cubic meters of waste per day. By the end of the third century BC it became necessary to regulate the torrential floods of the Tiber River. This was done by enclosing the river in stone embankments laid out in stepped stages. This method proved to be very effective, and was also used to regulate the Arno River. Other notable efforts were accomplished in the drainage of land for farming. In 280 BC Manius Curius Dentalus drained the marshes of Rieti by cutting a 2,624-foot-long canal which was led deliberately to a precipice, forming a dramatic waterfall. In 109 BC work on reclaiming the Po Valley was begun under the direction of Aemilius Scaurus for the purpose of settling veteran soldiers as farmers. This was done by cutting a system of canals through the valley which were also used for navigation. The reclamation in this previously uninhabitable area went on for hundreds of years. This fertile area, known as Cisalpine Gaul, became the "cockpit of creativity in the western world." One notable project involving roman reclamation efforts can be found in the Facinus Emissarium. This was a project ordered by Emperor Claudius which involved lowering the level of the Lacus Fucinus in order to gain approximately 38,000 acres of new farmland. This project required the digging of a 3.5 mile long tunnel through rock. The tunnel was completed after 30,000 men labored for 11 years. 4.2 The Roman Aqueducts The enormous and monumental works accomplished under the Roman Empire were largely a result of totalitarian power. It was the availability of free labor provided by slaves, and the ability of the Emperor to exert his totalitarian power which made possible these capital and labor intensive projects. The aqueducts of Rome are an extraordinary example of engineering. What remains of these great structures are monuments of construction that was well ahead of its time. 4.2.1 Aqua Appia Up until 312 BC the method of collecting water in buckets from local sources was adequate. But as Rome grew, the need for an outside water source became necessary. The first aqueduct built in Rome was called the Aqua Appia, by Appius Claudis Caecus. The Appia's water source was located between the seventh and eighth milestones of the Via Praenestina. The Appia then ran underground for 10.6 miles, crossing the east wall slightly northwest of Porta Maggiore, and was carried on arches for several hundred feet. The Appia then ran in a southwesterly line through the lower parts of Rome, and terminated in a reservoir on the south bank of the Tiber near Clivio dei Publicii. From this terminal reservoir the water was piped to 20 distribution reservoirs. It was estimated that the Aqua Appia supplied 1,825 quinaria of water per day. This translates to approximately 75,737 cubic meters per day. 4.2.2 Aqua Anio Vetus The next aqueduct, the Anio Vetus, was completed in 269 BC. It got its name because it drew its water from the Anio, a tributary of the Tiber, the source of which is in the mountains east of Rome. The source of the aqueduct was at Varia, 22 miles from the city of Rome. The aqueduct itself, however, at 41 miles, was almost twice as long because it had to maintain grade through mountainous country. From Varia the Anio Vetus followed the grade of the Anio River until it reached Tivoli. At this the point the river cascades into the plains. In order to maintain grade the aqueduct parted from the river, making a southeasterly loop, and continued to make a series of loops through the hills until it reached a volcanic ridge to the southeast of Rome. This ridge eventually came to carry four more aqueducts. The aqueduct entered the city through a tunnel, crossing the Aurelian wall in the neighborhood of Porta Maggiore. It terminated in a settling basin slightly northwest of the Julia Fountain. The majority of the Anio Vetus was underground, with only 201 paces of arches. The capacity of this aqueduct was 4,398 quinariae, or about 182,517 cubic meters per day, more than twice the amount supplied by Appia. It supplied the lower 10 wards in the eastern part of the city. 4.2.3 Aqua Marcia The first two aqueducts proved to be sufficient for 127 years. During this time the higher parts of Rome had to get their water from local wells. But by 144 BC, the population had more than doubled, and had outgrown the existing water supply. At this time the Roman Senate passed a water bill which allotted funds for repairing the badly neglected Aqua Appia, and Anio Vetus, and ordered the building of a new aqueduct. This new aqueduct was called the Marcia, named after Quintus Marius Rex who completed the project in four years. This aqueduct was a much more challenging project than the previous two. The source was a pool of green water near the present hamlet of Morano, about 23 miles from the city of Rome. The total length of the Marcia was nearly 58 miles, seven-eighths of which was tunnels. Marcia followed the Anio down to Trivoli just as the Anio Vetus had. However, at this point the Marcia followed nearly a straight line through the mountains, requiring three major river crossings. To cross these rivers, the conduit was carried over the gorge by huge bridges or viaducts. One of the viaducts, Ponte Lupos, still stands, and measures 97 feet above the bottom of the gorge and is 370 feet long. Marcia then followed the same volcanic ridge as the Anio Vetus, and emerged near Roma Vecchia where it was carried by an embankment, then by arches that kept growing in height reaching a maximum elevation at Porta Furba. The arches continued from here and crossed the Aurelian wall near Porta Maggiore. Continuing on these arches through the city, Marcia terminated in Castellum Aqua inside the Republican wall. A branch was built from here to Capitoline, and another branch carried water to houses on top of Caelian Hill. Another branch built in AD 212 carried water from a tap near Porta S. Sebastiano to the Baths of Caracalla. The Marcia brought the best quality water to the city, and was the first aqueduct to serve the high elevation districts of Rome. It had a capacity of 4,690 quinariae, or 194,365 cubic meters per day, which was larger than each of the previous aqueducts. 4.2.4 Aqua Tepula and Aqua Julia The first three aqueducts, Aqua Appia, Anio Vetus, and Marcia, were all constructed of solid stone, ashlar, sperone, peperino, and tufa, and were much more structurally sound than the aqueducts that would come later. These later structures had a core of coarse concrete faced with ashlar or brick, and were often poorly built. The Tepula was built in 125 BC, tapping tepid springs near the twelfth milestone of Via Latina. When the Tepula was brought out of the ground it rode piggyback on Marcia's arches for 6.5 kilometers into Rome. Another aqueduct, the Julia, with a source near that of the Tepula was built in 33 BC, and was also stacked on Marcia's arches. Because these structures were stacked, they were able to supply higher elevations than Marcia originally could. However, their water was of poor quality. All that remains of Julia is the Julia Fountain which is the only ancient fountain that has survived destruction. The Tepula was 18 kilometers long and had a capacity of 445 quinariae, or 18,467 cubic meters of water per day. The Julia was 23.1 kilometers long and supplied 1,206 quinariae, or about 50,043 cubic meters of water per day. 4.2.5 Aqua Virgo Aqua Virgo was built in 19 BC, and for the most part has remained in use until the present. This aqueduct was built by Agrippa to supply the baths on Campus Martius, which is near the Pantheon. The source of this aqueduct was a spring located near the eighth milestone of Via Collatina. Instead of bringing water into the city through Porta Maggiore like all previous aqueducts, Virgo entered the city from the north. The quality of Virgo's water was very good, comparable to that of Marcia. Virgo was 21.2 kilometers long and supplied 2,504 quinariae, or 103,916 cubic meters of water per day. The aqueduct has suffered through many periods of use and disuse, but today a cast iron conduit is still in use which runs through the tunnels originally excavated for Aqua Virgo. 4.2.6 Aqua Alsientina In 2 BC Augustus built a 20.4 mile underground conduit called Aqua Alsientina. The source of this aqueduct was Lake Alsiente, now known as Lake Martigano, northwest of Rome. Alsientina entered the city from the west, and had a capacity of 392 quinariae, or 16,228 cubic meters of water per day. The purpose of this conduit was to supply a small man-made lake called naumachia on which mock naval battles were carried out. The water supplied by Aqua Alsientina was not suited for human consumption. 4.2.7 Aqua Claudia and Aqua Anio Novus The Aqua Claudia, and Aqua Anio Novus were a joint project which together supplied 9,345 quinariae, or 387,817 cubic meters of water per day to all parts of Rome. The sources of these two aqueducts came to be known as the Blue Spring, and the Curtain Spring respectively, and were both located near the thirty-eighth milestone on the Sublacentian Road. The project was begun by Caligula who died in AD 38, and completed under Claudius in AD 52. The Aqua Claudia was a 43.3 mile long aqueduct of which 34 miles were underground. The Aqua Anio Novus was even longer at 54 miles, and 45.3 miles were underground. Both of these aqueducts followed the Anio River, running parallel to Aqua Marcia. But at Tivoli, they followed a sweeping path further to the southeast, bringing them to a spur south of Rome. From this point, at a place called Capanella, the conduits came out of the ground, and were carried together on tall arches for the last 6 miles into Rome. The two aqueducts entered the city at Porta Maggiore, which was constructed as a monument to facilitate this entrance. The two aqueducts terminated in a castellum slightly to the west of Porta Maggiore, from which water was distributed throughout the city. Aqua Claudia, and Aqua Anio Novus remained in unobstructed service for only ten years. Due to the size of this "giant", it required an extraordinary amount of maintenance, and required constant repair. 4.2.8 Aqua Trajana and Aqua Alexandrina Aqua Trajana, built in AD 109, also entered the city from the west. It was 35.4 miles long, and supplied approximately 2,846 quinariae, or 118,127 cubic meters of water per day. The source of this aqueduct was Lake Bracciano. From there it ran underground, and terminated in a reservoir or settling basin in Janiculum, which is in the neighborhood of Villa Spada. The Aqua Alexandrina, built by Alaxander Severus in AD 226 drew its water from springs to the east of the city. This 13.7 mile long aqueduct supplied the Therma Alexandrinae, the rebuilt Nero baths near the Pantheon. This aqueducts capacity was 521 quinariae, or 21,633 cubic meters of water per day. It was the last aqueduct built in Rome. 4.3 The Scope of the Roman Aqueduct System At its peak, Rome's system of 11 aqueducts measured 312 miles long, with 262 miles consisting of underground tunnels, and the rest being arched structures. The total capacity of this system was approximately 1 million cubic meters of water every 24 hours. To put this in perspective, the present day District of Columbia is about the same size Rome was in AD 300, and can provide roughly 67 gallons of water per person. The aqueduct system in Rome in AD 300 provided an estimated 200 gallons of water per person. A lot of this water was used to supply public fountains and baths. These figures are astonishing, and reflect the vast size and excellent overall quality of the Roman water network. 4.4 Construction of an Aqueduct Building an aqueduct involved one main concern, leveling. When an aqueduct followed a river, the grade of the river could be followed and used as a reference. However, when the Roman engineers had to construct aqueducts through the hills, maintaining the correct gradient became more difficult. The leveling was done using a tool called the chorobates, which was a 20 foot long board that could be leveled with a plumbline, or by filling a groove cut in the top with water. Using this tool an experienced tunnel builder could establish a grade with an accuracy of 1:2000. In order to maintain grade over river crossings and gorges, spectacular arched bridge constructions called viaducts were built to carry the conduit. The size of some of these structures was astounding. Due to the large above ground structures, and the amount of tunneling that was required to complete an aqueduct, these projects usually took many years, and involved mobilizing hordes of workers. The enormous labor force consisted of slaves, or prisoners of war. Because the overseers of such projects realized that better treatment resulted in better performance, these slaves were treated very well, and many were eventually integrated to became Roman citizens. When the aqueducts were cut in soft ground they were lined with masonry. When they were cut through rock they were left unlined. The above ground arches were built entirely of stone in the earlier aqueducts, but in the later aqueducts the main specus was made of a rough concrete, and faced with stone. At the source of each aqueduct there was a settling tank to remove solids from the water preventing the clogging or silting up of the conduits. In the city each aqueduct ended in a castellum, or distribution basin. This basin had three outlets at the lower level which served fountains, baths, and public buildings, and higher up in the basin were the outlets that served private consumers. Overflow was used to flush drains, or turn water wheels. 4.5 The Roman Water Administration Most of what is currently known about the Roman system of aqueducts was derived from a book written by Sextus Julius Frontinus, who served as the Curator Aquarium from AD 97 to AD 104. He was appointed to this office by Nerva in order to restore the long neglected and abused water system. Frontinus was very instrumental in restoring the aqueducts, and doing away with the corruption, and fraudulent practices that had left the system in a state of disrepair. Frontinus kept very accurate records, by taking inventory of the entire system, and detailing the technical aspects of how such a system should be maintained. After correcting all of the problems that had occurred, Frontinus began making improvements to the system in order to make it more efficient. In order to ensure that the work he had done would continue when he left office, Frontinus set a standard to be followed, and wrote a number of bills that were enacted by the Roman Senate. 4.6 The End of the Roman Aqueducts Just as all great things must come to an end, so did the Roman system of aqueducts. As was pointed out previously, with a water distribution system of this scale, a continuous maintenance effort is required. Otherwise the system will deteriorate and fall into disrepair and disuse. When the Roman economy went into decline, so did the water infrastructure. The final destruction of the Roman system of aqueducts occurred in 537 AD during a siege on Rome by the Goths. The Goths built an encampment between two lines of arches of the Aqua Claudia, and the Anio Vetus, in which they housed 7,000 troops. From this fortification they conducted raids on Rome, and demolished the aqueducts in an effort to deprive the city of water. They even attempted to send troops through the dry conduits to attack the city. After the siege, there was an effort to repair the aqueducts, but they eventually fell to disrepair and neglect, with the exception of Aqua Virgo, which remains in use today. 4.7 Roman Harbors and Docks Because road transport was sometimes inadequate and inefficient, the Roman economy relied heavily on moving goods by sea, and river. This need led to the development of docks and harbors, which were very elaborate. Portus Rome is one of the best examples of Roman water transport infrastructure. This was a man-made port west of Ostia that was completed in AD 100. It had two harbor basins which were completely protected from the open sea by two moles. At the entrance of these two moles stood a lighthouse which served to guide ships into the harbor. The outer basin had an area of 247 acres, while the inner basin had an area of 115 acres, and a maximum depth of 16 feet. The pozzolana concrete blocks lining the basin sit under water, and have resisted the chemical and physical effects of the salt water for nearly 2,000 years. List of References Blake, Marion E.: Roman Construction in Italy From Nerva Through the Antonines. The American Philosophical Society, Philadelphia, 1973. Cornell, Tim and Matthews, John: Atlas of the Roman World. Facts on File, Inc., New York, 1982. Gest, Alexander P.: Our Debt to Greece and Rome: Engineering. Longmans, Green and Co., New York, 1930. Sandstrom, Gosta E.: Man The Builder. McGraw Hill Book Company, Stockholm Sweden, 1970. Von Hagen, Victor W.: The Roads That Led To Rome. The World Publishing Company. Great Britain. 1967.