Witherford Watson Mann and Kinnear Landscape Architects’ transformation of a Victorian waterworks into a public nature reserve demanded delicate handling of history and ecology, explains William Mann

Words
William Mann
Photos
Jason Orton, Heini Schneebeli

The chain of reservoirs at Walthamstow, east London, occupies 200 hectares, and over the years has developed rich habitats supporting migrating wildfowl. Yet until October 2017 it was only accessible to birdwatchers and anglers with permits. Access for the general public has been long anticipated – and long deferred – but in 2008, the Greater London Authority and other local authorities commissioned the Upper Lea Valley Landscape Strategy, prepared by Witherford Watson Mann Architects and Jonathan Cook Landscape Architects. Amongst many projects of ‘urban acupuncture’ and guidance for large development sites, one stood out for its transformative potential: the ten reservoirs either side of Ferry Lane and the cluster of open spaces around them offered an area the size of Hampstead Heath, and was given the collective identity ‘Walthamstow Wetlands’.

Top, above: views of the visitor centre before and after restoration and extension (phs: Jason Orton)

In 2012, Kinnear Landscape Architects and Witherford Watson Mann were appointed to design the facilities necessary for opening the site to the public, including the renovation of two buildings. These were robust brick boxes, built to house the monstrous engines that pumped water up to the city. Although only grade II-listed, they are hugely communicative structures, integral to the identity of the site. The Coppermill, at the southern end, is a remnant of an 1806 watermill, later altered to house a beam engine. The Engine House, close to the site’s Forest Road entrance, is now a visitor centre. Built in 1894 for a giant triple expansion engine, it was extended in 1908 to house steam turbines. A simple cluster of rooms, it is squeezed into a triangular riverside plot. Its 30-metre-tall chimney was demolished in the 1960s, leaving it feeling lopsided and diminished.

Ph: Heini Schneebeli

The visitor centre is an elusive building type, prone to changing patterns and fashions of operation, so it seemed if anything an advantage to adapt an existing structure, rather than starting with a blank piece of paper. At the Engine House, we inherited three large masonry rooms: the central Boiler Room, the Turbine Room in white glazed brick, and the 15-metre-high Triple Engine Room. While the core brief of reception, shop, cafe, exhibition areas and education space were fixed early on, the new uses don’t map neatly onto the old brick cells; instead, we welcomed the fact that activities and atmospheres blur and flow through the building.

Public open space at Walthamstow Wetlands; site plan.

We also ensured that we made the most of existing characteristics to offer places of repose, meeting and outlook. This approach required us both to submit to the cellular logic of the masonry, and to transgress it. We unblocked bricked-up openings, and punctured new doorways through the thick brickwork walls, so that the central Boiler Room provides access to all the other rooms, and entrances to both north and south – a bit like the hall in an Edwardian house.

Approach to the Engine House from under the adjacent railway line to the north, with new steel entrance ramp and spiral escape stair (ph: Jason Orton)

We added two new cells to the existing cluster of rooms. We made the new kitchen a single-storey room in arcaded brick, like the adjacent north wall. Onto the old chimney plinth, we grafted a new chimney-like structure: built in a purple-brown engineering brick, it is punctuated by a series of nesting boxes for swifts in red clay. Visible along the valley and from the River Lea, the swift tower signals repair and transformation: repair of civic infrastructure, transformation from pollution to ecology.

We levelled the ground floor, and added a gallery around the edges of the Boiler Room, served by steps and a lift to accommodate the remaining half-level. We inserted a first-floor five metres up in the Triple Engine Room, perforated by a large void to maintain the sense of volume. The new beams cantilever out to form a deep public balcony looking south over the reservoirs. The stairs and lift rise within the Boiler Room, within new timber lantern rooflights, which bring a soft, warm light.

Boiler Room containing the reception, shop, and exhibition space (ph: Heini Schneebeli).

Responding to the Lea Valley’s ‘edgelands’ character, Kinnear Landscape Architects has added reed beds, wildflower meadows and pollarded willows, and steel bridges, boardwalk, terrace and ramps. The steelwork binds landscape and buildings, a path threading through and above the valley floor, at times direct and robust, at others oblique and delicate; its rusty hues are fiery in the landscape, while its bluish tint is cool against the warm brick walls.

Cafe in the Triple Engine Room (ph: Heini Schneebeli).

The gantries, lifts and stairs weave through the Victorian brick boxes like a family of steel spiders, passing through arches, bridging voids and touching the walls lightly. They share a simple language of plates, stiffener angles and vertical balusters, but respond to wildly varying spatial constraints – a constant test of our ingenuity. We stepped the underside of the cantilever beams, extrapolating the profile of the brick string course below. The external escape stair hides in plain sight as an airy steel column echoing the brick tower nearby. At the Coppermill Tower, the stair is suspended from the viewing platform by steel rods to the half landings. It zigzags through the masonry shaft, an oblique recollection of the rocking arm of the beam engine.

The design approach is coherent between landscape and architecture, and shares a common vocabulary. Steel pathways run through landscape and buildings, leading to elevated viewpoints where you can look out over the wide flood plain. Landscape interventions included pedestrian entrances and bridges, a foot- and cycle-path through the site connecting to the wider Lea Valley, signage and interpretation, and a small car park (ph: Jason Orton).

So the interventions do not follow a singular logic, but multiple ones. Internalising the picturesque tactics of the original buildings and landscape offered us opportunities and helped us solve problems. The swift tower and lantern rooflights are both restorative actions, reinstating lost volumes in approximate form. The new masonry cells and carpentry frames graft onto existing structures, using capacity and following rhythms that are already present. They are materially distinct, using engineering brick rather than fine red brick, and lacquered rather than painted wood.

The steelwork is the one element where new construction has a consistent identity, a little bit alien to the existing buildings, but geometrically responsive, sometimes even mimetic. The cool metallic gantries and stairs jog the collective memory about the machines that once occupied these vast rooms. At the same time they introduce movement and scale, perforating and tempering these infrastructural buildings for the human body. Our multiple additions and adaptations transform these durable structures into places of repose, meeting and outlook.

Additional Images

Download Drawings

Credits