Rio Monterroso

The 3rd version of the Arroyo de Juan Benítez is located on the eastern wall of the Monterroso culvert, flowing directly under the Calle Parque central.[20] Version 3 is the largest of all versions of arroyo de Juan Benítez culverts. This is one of 3 versions of outfalls located on the eastern wall of the Monterroso culvert. Version 3 was built to relieve version 2, which had a 90° (right angle) internal bend and caused problems with water flow. It consists of a 5-foot tall rectangular concrete outfall, with ceilings that slope up to 6'5" inside and slant to the right. This shape limits the flow of the Juan Benítez stream in times of flooding to minimize erosion, and prevents the Monterroso river from backing up into the Juan Benítez culvert.

Version 3 Present Day Arroyo De Juan Benítez culvert

It is surrounded by a steel beam and two columns, with the measurements of the beams and columns, a total weight of 1,042 kg (2,297 lb) is added and resulted. A calculated weight of 492 kg (1,085 lb) for the top horizontal steel beam with a length of 9 feet 10 inches (3.00 metres) and a weight of 275 kg (606 lb) each for the two steel columns either side with a height of 5 ft (1.5 m).[21]

It was 22 November 1989 when the 3rd version of the Juan Benítez culvert was announced to be ongoing construction. Whilst heavy storms and flooding occurred during an news interview with the mayor of Estepona, it was said that the Arroyo De Juan Benítez Embovedamiento project was very important and the new embovedado would be completed if they managed to get enough concentrated personnel.[22]

Version 2 of the Juan Benítez culvert outfall is located 160 metres north from the current version Juan Benítez outfall. It is same shape, except with slightly smaller height, and stays the same height its entire length. It had a 90° bend inside that caused hydraulic problems which was the reason the third version of the culvert was built.

2nd version of the Arroyo De Juan Benítez culvert in 2019

Version 2 previously was built to relieve version 1 of its duties as it also had a 90° (right angle) bend. Due to the circumstances, the version-2 culvert was built with the same exact same right angle as before, which was later resolved in the version-3 modern day culvert.

Version 1 Arroyo de juan benítez

The 1st version of the culvert is located quite a distance from the previous outfalls and is located only 140 metres from the northern inlet of the Rio Monterroso culvert. Its outfall is located directly under Av. J. Martín. Mendéz[23] and it has a different design than the other two, consisting of a vaulted ceiling and a channel on the floor designed to channel the water through the centre so that water does not accumulate. It was built with a 90° (right angle) bend that was located under San Fernando football stadium.[24]

Versions 1 and 2 are now both bricked up and unused. Version 2 has accumulated silt and concrete debris from lack of use.

Air view of the Monterroso river 1965 original culvert.

In 1881, with the construction of the n340 highway, A bridge was constructed over the river for the passing of vehicles.[25]

In April 1965, the Monterroso River was originally culverted on the coastline and extended was approximately 45 metres (148 ft) long for use as the n340 passover. The n340 is a road over 1000 km long, was the only road connecting two halves of southern Andalusia, and had large amounts of traffic. The culvert was originally budgeted at 294,053.93 Pesetas however the finish price costed 9,828,431.02 Pesetas.

45 Metre Culvert Construction in 1965

[26]

Like the original Monterroso river culvert, most Spanish culverts from that era featured a vaulted ceiling, which is where the name "Embovedado" comes from when associated with culverts in Spain.

In 1970 the original 60s culvert was extended with a rectangular beam bridge with a span of about 10 metres, 3 years later the modern Av de Juan Carlos 1 culvert was constructed using the same dimensions as the bridge. The arches of the original culvert were embedded into the bridge.

1970 Photograph of the River Monterroso

On October 10, 1986, due to the funneling effect of the rectangular culvert, the 1965 culvert shifted breaking apart the surrounding bridges, causing a 700 square metre sinkhole.[27]

Inside the Monterroso river culvert, there are storm drains and sewers connected to the outfall into the culvert system via pipes. The pipes range from 5 inches to 4 feet in size, and there are over 500 outlet pipes that flow into the Monterroso culvert.[28]

Examples of the drains in the Monterroso and Juan Benítez culvert.

However, the most common seems to be 8-inch concrete cut-outs in the wall that were created when the culvert was first constructed. These pipes are called lateral pipes and are installed using a core-cutting machine into the walls.

Lateral pipes installed during construction are created by casting the concrete wall and creating a template in the desired shape/size of the pipe in the liquid concrete.

These consequences could range from the simple unwanted factors of the river water back flowing into the lateral pipe, to turbulence in the water flow[29] potentially inducing currents that erode its surroundings.

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  The river Monterroso original collapsed culvert being built over.
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  First version of the arroyo de Juan Benítez culvert in 2020.
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  River Monterroso Culvert Inlet
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  River Monterroso Culvert inlet
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  The River Monterroso Culvert on the beach
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  Construction of the river Monterroso culvert in the 1970s
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  7 inch pipe outputting greywater and stormwater during rain
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  The construction of the 1965 culvert
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  The Arroyo De Juan Benítez outfall in the river Monterroso culvert

• Mediterranean Sea