The Environment Agency has allowed Angus Energy to dispose of water underground at the Brockham oil site in Surrey.
The decision follows a public consultation during December 2021 and January 2022 on plans to reinject waste through an existing borehole at the site into Portland sandstone rock.
Angus Energy had wanted to reinject waste from Brockham and other oil fields, including Lidsey in West Sussex.
A previous application by the company for water reinjection at Brockham was refused in 2019. Then, the Environment Agency (EA) said there was a lack of suitable information in the hydrogeological risk assessment.
On the latest decision, an EA spokesperson said:
“In deciding whether or not to issue this permit variation, the Environment Agency took into account all relevant considerations and legal requirements.
“An environmental permit sets out stringent conditions that all oil and gas sites must adhere to. We will not issue an environmental permit for a site if we consider that activities taking place will cause significant pollution to the environment or harm to human health.”
In its draft decision, issued in December 2021, the EA said there was a “negligible risk of pollution to groundwater”.
But Brockham Parish Council, local councillors and campaign groups said they were also concerned about Angus Energy’s operational record at Brockham.
The waste water, also known as produced or formation water, often comes to the surface during oil and gas extraction. It is usually very salty and may be radioactive.
Companies seek to reinject it into boreholes to avoid expensive water treatment and to support the pressure in the hydrocarbon reservoir, improving oil and gas flows.
There are concerns that waste reinjection could cause earthquakes. Brockham is 7km away from the Newdigate area, which saw a swarm of earthquakes in 2018 and 2019.
The EA’s final decision document and permit has not yet been published.
But last year that Angus Energy would be allowed to reinject up to 24m3 of produced water per seven hour day. The injection rate should be no more than 1.3 litres/second. Pressure would be below that needed to fracture the rock formation, the EA said. Company procedures would ensure the reservoir did not become over-pressurised.
In a press release, the regulator said:
“It is a condition of the permit variation that the waste water to be re-injected must originate from operations at Brockham oil site. This condition is made clear in the Decision Document and in the introductory note of the permit.”
The variation document, published nearly three weeks later, said:
“imported produced water resulting from the extraction of hydrocarbons at other sites is only permitted
when a separate bespoke Radioactive Substances Activity permit has been obtained. “
Surrey County Council said last year that the Brockham site did not have planning consent for importing waste water.