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Kilvey Hill history: from copper smoke to community woodland

Kilvey Hill looks green today, but for about two hundred years it was poisoned by smoke from Swansea's copperworks, which killed its plants, and industrial waste was tipped on its slopes. This is the story of how it got that way, and how it was replanted from 1969 onwards.

About our sources: most of the detail on the 1969 to 1990 replanting comes from one report, the Kilvey Hill Woodlands Ecological Constraints and Opportunities Plan (January 2023), written by Nigel Robins for the Kilvey Hill Woodland Volunteers. It is not an official council document, so we name it every time we use it. Checked 27 October 2026.

The hill's names

The historic Welsh name of the hill is Y Bigwrn, and its summit was known as Pen y Bigwrn. Today it is generally called Mynydd Cilfái in Welsh (Wikipedia).

Before the copperworks

Coal: the hill was mined for coal from early medieval times, and it is "honeycombed with over 700 years of coal workings". In the 1830s the geologists William Logan and Henry De La Beche used Kilvey's coal mines to map Swansea's coal seams (Kilvey Hill ECOP, 2023).
A windmill: near the summit are the round foundations of a windmill built in the 17th century to grind corn (History Points).

Copperopolis: the copper smelting years

In the 19th century Swansea was the world's leading copper smelting centre. It smelted 90% of the UK's output and became known as "Copperopolis" (Swansea Council: Lower Swansea Valley). The council's Hafod Morfa page says about half of the world's copper was smelted in the Lower Swansea Valley, and that by 1850 there were 11 major copperworks there (Swansea Council: Hafod Morfa Copperworks).

Two works matter most to Kilvey Hill:

White Rock Copperworks, on the east bank of the River Tawe next to Pentrechwyth Road. It opened in 1737, was the third oldest copperworks in Swansea, and closed in 1924 (Swansea Council). The site is now the White Rock Industrial Heritage Park.
Hafod Copperworks, across the river. John Vivian, a Cornish businessman, opened it in 1810. By 1890 it was the largest copperworks in Europe. It merged with the Morfa works in 1924 and was the last to close on the site, in 1980. The Musgrave and Vivian engine houses and the rolling mill still stand (Swansea Council). You can visit the area today: see things to do.

The first copper smelter in the valley was set up at Landore in 1717 (Wikipedia: Lower Swansea Valley).

What the smoke did to the hill

The prevailing westerly winds blew much of Swansea's industrial pollution onto Kilvey. By the 1790s the hill was badly affected by copper smoke from the White Rock and Hafod works, and in the 19th century copper slag was dumped on it (Kilvey Hill ECOP).
From the early 1800s the owners of White Rock bought land on Kilvey to tip their waste, and to avoid paying compensation to farmers for poisoned land. The hill became known as the "White Rock Tip" (Kilvey Hill ECOP).
In 1854 a local doctor, Thomas Williams, wrote a book called The Effects of the Copper-Smoke, describing the landscape and the complaints of local farmers (Wikipedia).
In the 1870s a flue was built up the side of the hill to carry gases away from a lead and silver smelting plant at Hafod (History Points).
In 1886 the newspaper The Cambrian said pollution had killed the hill's plants, leaving "one great mass of soft, loose brown earth". In a storm that September, mud and rocks, some weighing about half a ton, slid down onto terraced houses in Foxhole. Some people were hurt and many families were made homeless for a time (History Points).

The Grenfells and Maesteg House

On the south-western slope stood Maesteg House, built by Pascoe St Leger Grenfell (1798 to 1879) of the copper firm Pascoe Grenfell & Sons. He was a slave-owner: when Britain abolished slavery he had to free 216 enslaved people on an estate in Jamaica, and the government paid him £4,122 in compensation. The enslaved people received nothing. He built housing for workers and All Saints Church, Kilvey, which closed in 2015. Maesteg House was later demolished for new homes (History Points).

The clean-up: the Lower Swansea Valley Project

Swansea Council says that by the end of the last century all the copperworks had closed, and that the area was left derelict for many decades (Swansea Council). Swansea Museum says the valley was left as the largest area of industrial dereliction in Europe (Swansea Museum).

In 1961 the Lower Swansea Valley Project began. It was paid for mainly by the Nuffield Foundation, the Welsh Office, Swansea Council and the then Department of Scientific and Industrial Research, with researchers from what is now Swansea University. Its final report came out in 1967 (Swansea University Richard Burton Archives). Over the next twenty years volunteers, local schoolchildren and the Territorial Army all helped to restore the land (Swansea Museum).

Kilvey Hill was never officially part of the project, but the trees chosen for it were based on the project's research into plants and soil chemistry (Kilvey Hill ECOP).

Replanting the hill, 1969 to 1990

All of this section comes from the Kilvey Hill ECOP (2023).

1969The hill is labelled "Plot 57" in the valley clean-up. Tip waste is removed, and by the end of the year the council has rebuilt the valley of the stream that runs through the middle of the hill. In late 1969 the council plants Scots pines as an experiment; many of these first trees still survive.
1970The Forestry Commission leases a large part of the hill and plants Lodgepole pine, Scots pine and hybrid larch. The council also plants a stand of Monterey pines, now the largest trees on the hill.
1977More Lodgepole and Corsican pine are planted.
1980More Lodgepole pine goes in on the north side, over what had been badly polluted slag waste.
1987 to 1990Mixed conifers fill the gaps, completing the forest planting.

Pines were used because they could survive in the hill's toxic soils. The report says the pollution is still there under a thin layer of new soil. It also says the hill has suffered from wildfires and arson since the 1970s, and that native trees, led by oak, are now spreading naturally into the gaps. Natural Resources Wales, which took over from the Forestry Commission in Wales, later gave up its lease on part of the hill (Kilvey Hill ECOP).

Other landmarks

The transmitter: the BBC built the TV relay station at the summit in 1967 (Wikipedia).
The Quaker seat: a seat built by Quakers stands a short distance east of the summit (History Points).
The Kilvey Arch: an arch carved from a single oak trunk by artist Nansi Hemming, put up in March 2001. Its panels show life and nature on the hill from prehistoric times to today (Kilvey Hill ECOP). We have not checked whether it is affected by the current works.
The Kilvey Killer: a charity race up and down the hill carrying a sack of cement, started in 1989 by boxing trainer Nigel Page to raise money for the baby unit at Singleton Hospital (Wikipedia). Whether it still runs each year is to be confirmed.

Kilvey Hill today

Swansea Council describes the hill as a young community woodland of about 3 km², with woodland, heath, wetland and meadow, managed by the Kilvey Community Woodland Volunteers, Forest Enterprise and the council (Swansea Council). Skyline Swansea is now being built on part of it; Skyline says it will cover less than 9% of the hill (Skyline FAQ). In August 2026 its workers found the remains of a small stone building at the top of the hill, which has been recorded with Archaeology Wales (Skyline).

Read on: views from the top, how Skyline Swansea got planning permission, or walks and bike trails.

Sources for this page

Facts on this page last checked: 27 October 2026. Things change during construction, so check the linked sources before you set off.