爱尔兰阿克隆污水处理厂丨Clancy Moore Architects

Out of the sewer: wastewater treatment plant in Arklow, Ireland by Clancy Moore Architects

The large volumes of Arklow’s new wastewater treatmemt plant, 65m long, form a civic landmark visible across the river from the town

Among the existing industrial sheds and tanks of chemical waste, the buildings’ large scale starts to playfully distort

The entrance to the site is looked over by a small office building that uses a finer dialect of the language used in the large sheds

complex contracts, the office’s internal arrangement does not follow Clancy Moore’s original designs

In the first volume, the wastewater is ‘deragged’, ‘degritted’ and ‘desludged’, and the material removed from the wastewater is taken away by lorries. Thick pipes snake around the volume, diligently extracting any escaping odours and releasing them above the building’s parapet

Louvres of corrugated fibre‑cement hang from a steel structure that sits on concrete feet

Wastewater travels through sewers underground to a well, from which it is pumped up to an upper level for initial treatment.

The volumes are loosely held in an urban assemblage, suggesting squares and streets

Large windows punctuate the facades like unseeing eyes

The internal arrangement evolved without respect for the window locations approved in planning – the view of the town is foregrounded by the aeration tanks

Most people in Arklow will experience the building from afar, as a monument on the shoreline: a public building that is largely inaccessible to the public. It is hoped that the local ecology will greatly benefit from the newly clean river and sea water

The Arklow wastewater treatment plant in Ireland, designed by Clancy Moore, is an act of public service

The Irish Sea near the town of Arklow was once home to 90km of naturally occurring oyster reefs. During the 19th century, Arklow was the country’s main port for oysters – 40 million were harvested in 1863, with many exported to England, the colonial metropole. But by the end of the 1800s, the oyster beds were depleting due to over‑harvesting and pollution from the Avoca mines upstream; even in the 1860s, oysters were rebedded elsewhere to remove the taste of copper, dispensed into the river by the mines, before being sold.

Since the 19th century, the water quality of the Avoca River and the sea into which it discharges has suffered, due to both industry and a lack of wastewater infrastructure. Until June 2024, when the new Arklow wastewater treatment plant began operation, raw sewage – as well as greywater and surface runoff – was released directly into the river. The lower reaches of the Avoca River constituted the most polluted stretches of river in Ireland, according to a 2003 Eastern Regional Fisheries Board report. In 2019, the European Court of Justice took Ireland to court for its failure to treat wastewater in Arklow, along with 37 other Irish towns.

Attempts to build a wastewater treatment plant began in the 1990s but were frustrated by searches for a suitable site. In 2016, a location was selected at the mouth of the Avoca River, next to the marina – and prominently visible from the town to the south. ‘We came to the conclusion that if we’re going to build something there, it needs to be a civic building that we’re proud of and that speaks to the town,’ explains Michael Tinsley, an engineer and senior manager at Uisce Éireann (formerly Irish Water), who commissioned the project. ‘We need to get an architect involved here.’ There was an invited competition in 2016 for a practice to join the existing design team, led by Arup and Ayesa Engineering. Dublin‑based practice Clancy Moore were an unlikely addition to the line‑up, invited on the commendation of a planner who had been impressed by a house on a sensitive quarry site which the practice had designed in 2008.

‘The lower reaches of the Avoca River constituted the most polluted stretches of river in Ireland’

Clancy Moore found themselves a consultant among many; around 20 specialisms were represented in the design team (odour engineerarticularly niche favourite). In the built project, however, the architects’ hand is keenly felt. From a distance, the monumental louvred volumes appear almost toy‑like, emerging from between tanks and warehouses like oversized pleated origami. This is how the buildings will be experienced by most people: a landmark viewed across the river from the south quay or glimpsed on a windy walk by the sea to the north. As Andrew Clancy, co‑founder of Clancy Moore, explains, ‘while not accessible to the public, the project is fundamentally for and about the public good’.

Clancy Moore have achieved more than just smart dresses for giant sheds. In one of many meetings, the architects casually asked if it was possible to ‘put this on that’, marking a departure from typical sewage plant design, in which processes are arrayed horizontally and tanks are sunk into the ground. At Arklow, the initial treatment processes – where grit and non‑organic objects, such as wet wipes and nappies, are removed – take place on an upper level, with large storm tanks and skips for collecting the removed material below. Wastewater is pumped up to the raised level from the underground sewer and then flows by gravity to the second volume which contains aeration tanks – effectively giant petri dishes where bacteria break down harmful compounds – before making the journey down a kilometre‑long outfall pipe to the Irish Sea.

This decision to stack processes precipitated a chain reaction of happy consequences. Volumes were able to be more vertical: confident urban figures with a civic presence. The only evidence that the buildings are in fact part of a sewage works will be a lorry coming out a couple of times a week to take dried ‘sludge’ away to either be used as fertiliser or incinerated to generate electricity. The volumes had to have roofs because the higher areas needed to be served by gantry cranes, which in turn meant that solar panels could be installed on the roofs (currently just one roof but there are plans to roll out on the second in a couple of years). These will be able to contribute up to 40 per cent of the plant’s energy demands – reduced compared with typical arrangements, where wastewater is pumped between each tank rather than fed by gravity. The reduced built area also allowed a third of the site area to be rewilded, including plants that will help to decontaminate the ground.

The giant louvres, like half‑closed Venetian blinds, allow air circulation without revealing the unsavoury innards, and are already welcoming small birds looking for a nesting spot (though netting prevents wildlife from venturing further inside). The fins of corrugated fibre‑cement board, the colour of oxidised copper, hang from a steel‑framed carapace, the steel columns meeting the ground on hefty concrete feet, a precaution against manoeuvring trucks. The small office building at the site entrance speaks the same language as its two larger siblings but in a softer register, with concrete wedges supporting a portico that echoes the louvres, gently lapped cement‑board cladding in the same marine green, and windows in a dance along each facade, like notes on a stave.

The reference here to John Hejduk’s Kreuzberg Tower in Berlin is wittily rehearsed (the facade at the entrance resembles – I suspect intentionally – a face in profile), and the two louvred sheds heavily quote Hans Christian Hansen’s Amager switching stations in Copenhagen: large warehouse‑like buildings with corrugated louvres that flap up and down to allow ventilation. Clancy Moore’s project itself has also been quoted; before the wastewater plant was even completed, DMOD Architects’ headquarters for Arklow Shipping was built in 2022 with an oversized green sawtooth roof.

Concrete was a prerequisite for the tanks and other processes, for which no other material is suitable, and a steel frame was selected due to structural demands and the exposed marine location. The choice of fibre‑cement cladding emerged following countless iterative studies: a cast

concrete facade was vaunted as there was plenty more concrete already being poured on site, and timber options were considered, though it unfolded that withstanding the tough conditions would require slow‑growth oak and copper nails. This was unsurprisingly quickly dismissed. A hardier, more industrial palette was selected; the corrugated cement board rhymes with the surrounding industrial sheds, still used for shipbuilding.

‘One resident welled up as she noticed that the frothy scum that had habitually laced the edges of the river had disappeared’

The Arklow wastewater treatment plant is a rare example of a sewage works designed by an architect, and one of, if not the first in Ireland. The project was tendered as part of a design and build engineering contract that did not include a single drawing. Instead, the architects drew through writing, in a document of over 60 pages, meticulously describing the basis of the buildings: from the plans (‘a four‑sided structure, rectangular in plan’) down to the details (‘there are to be no horizontal joints between fibre‑cement panels’). The document proves, in case there were any doubt, that a drawing is worth several thousand words.

This is a project of conversation – between professionals from innumerable disciplines, and with planning authorities and local people. Clancy and co‑founder Colm Moore see the practice as ‘stewards’ or ‘guardians’ of the project, navigating and negotiating between the various specialist expertises placed on the table, rather than leading the project. They also proved to be crucial advocates of the project in consultations with the public: ‘The architects had them sitting down and within five minutes, they were nodding about how the project would speak to the marine history of Arklow,’ Tinsley describes. ‘Very early on we saw the benefit of having the architects involved.’

Tinsley also notes that there has been very little resistance to the project from the local community – perhaps expected given the previous dire situation, though unusual as ‘not everyone wants a sewage plant as a neighbour’. Any qualms that the public might have about frivolous spending of taxpayers’ money on aesthetics can be quelled by Tinsley’s estimates that only around 3 per cent of the project’s budget was spent on the ‘architecture’ – a small price to pay for a civic landmark.

This is a socially and ecologically transformative piece of infrastructure. On an open day shortly after the plant began operations last year, one resident welled up as she noticed that the frothy scum that had habitually laced the edges of the river had disappeared. But perhaps the most dramatic transformation that will result from the operation of the plant will be urban growth, suppressed since the late 1990s on the grounds that there wasn’t adequate wastewater treatment provision – the population of the town has hovered around 13,000 for the last 15 years. The new wastewater treatment plant is the key that will unlock development: the plant has the capacity to allow the town to nearly triple in size, with two tanks currently dormant. A single development of 476 units on a greenfield site to the south of the town was granted planning permission in December 2024.

But the town’s population had been suppressed since long before the 1990s. The population of the Republic of Ireland only recently, in 2022, surpassed five million for the first time since 1851, just recovering after centuries of English then British colonisation, including a genocidal famine. As Clancy points out, the population growth in Arklow will ‘not be an explosion, but a return to the normal population dynamics of the country as a whole’. He hopes young people may now choose to stay and that ‘a considered approach will be taken’ to urban development. ‘One small positive from the failure to build a plant before is that Arklow was spared the substandard developments of the boom, and of the last 10 years.’

The deprivation caused by British colonisation and economic mismanagement since independence in 1922 has resulted in underdeveloped infrastructure, including wastewater. In 2014, 50 Irish towns were without water treatment; Arklow was the 35th on the to‑do list (six more are set to receive treatment plants this year, and the last nine are at planning stage). The state‑owned water company Uisce Éireann, established in 2013, is funded through taxation rather than householder water bills (it is a strongly held principle in Ireland that ‘water is free’). In contrast, across the Irish Sea in England, privatised water companies operate as uncompetitive monopolies, extracting profit for shareholders while allowing water infrastructure to languish. In 2024, London’s private water company Thames Water was responsible for 300,000 hours of raw sewage overflowing into waterways, despite having over 350 treatment plants. The same year, it paid shareholders dividends amounting to £158 million. Thames Water has announced water bill increases of 31 per cent beginning 1 April to an annual average of £639 per household.

The new use of this site to clean water in Arklow is in stark contrast to its historical uses which excreted a plethora of toxic substances; a gypsum board factory, active between 1964 and 2002, was demolished to make way for the project, and an ammunitions factory for the English Kynoch Company factory was on the site before that. Even the soil itself – reclaimed from the sea during the 19th century – is likely contaminated spoil from the Avoca mines. Both the weapons and extracted copper and sulphur that continue to leave their traces in Arklow were used by England for imperial gain. Large rusting cylindrical tanks that held industrial waste remain on the site – a reminder of the toxicity that came before.

Today, the river runs clean for the first time in over a hundred years. There are hopes that the oysters will return.