We now have some facts about the poisons in the ground at Brighton Gasworks, and their likely effects on people living nearby.


On December 3rd 2020 the Policy and Resources Committee briefly discussed our Deputation of October 22 2020 and Phelim MacCafferty (Council leader) mentioned the Council’s response to Quod/St Williams’ Scoping Report dated July 2020. We hadn’t heard of this before.

A Scoping Report is written by developers in the pre-planning phase, and it highlights areas of potential concern and states how these will be dealt with so as to achieve planning permission. It also seeks to knock out issues which it states are not of concern.

Having read both reports we can tell you that Quod/St William state that there will be:

temporary generation of dust arising from demolition and remediation works leading to potential impacts on dust soiling/deposition within 500m of the Site boundary

temporary localised increases in traffic-related emissions (NO2, PM10 and PM2.5) during demolition and remediation works and as a result of any temporary vehicles operating on the Site and/or local road network, should HDV movements be greater than 25 AADT within or adjacent to an AQMA, or 100 AADT elsewhere; and
odour from the excavation and remediation works, albeit short term and temporary, owing to the historical uses of the Site and ground contamination

They also state that

The effects during the construction works also have the potential to result in dust nuisance complaints and surface soiling from deposition, as opposed to the risk of exceeding any air quality objectives. The impacts will be direct as they occur as a result of construction activities associated with the Development, temporary as they will only potentially occur during the construction works, short-term because these will only arise at particular times when certain activities and meteorological conditions for creating the level of magnitude predicted combine, and will be reversible.

Temporary vehicle movements (particularly HGV movements) associated with the construction works have the potential to generate exhaust emissions, such as NO2, PM10 and PM2.5 on the local road networks.

The level of significance of each likely effect will be determined by combining the magnitude of change with the sensitivity of the receptor.

(NB The main `receptor’ here is a human being! The developers say they will be on site for up to 8 years, which may stretch anyone’s definition of `temporary’).

We note that Quod/St William suggest that `odour' should not be a consideration in the planning process. They say:

It is unlikely the residual odour will cause adverse odour effects and a detailed odour assessment is considered to be able to be scoped out of the assessment.

(NB However at the recent Gasworks Communities United (GCU) conference Professor Watterson confirmed our suspicions that "if smells emerge from land where industrial activity ceased many years ago this is of concern").

Quod/St William have tested the site and state:

A review of historical land quality reports for the Site has been undertaken which has enabled a robust conceptual model and evaluation of land condition risks and constraints for the Site to be developed. The previous reports include exploratory boreholes, trial pits and remedial excavation information as well as soil, soil leachability and groundwater sampling data from multiple phases of investigation dating between 1993 and 2019.

The majority of exploratory holes (57 of 69) progressed outside of the known gas holder footprints indicate an average Made Ground thickness of approximately 1m, although deeper thicknesses of Made Ground is present at the southern boundary and at the position of infilled relict gas works structures. The Made Ground across the Site, excluding the material in the former gas holders’, was not described as stained or odorous, but does include slag, ash, clinker, metal fragments and/or coke chips. A number of exploratory holes refused on buried concrete and it is likely that relict gas works structures, foundation and pipes would be uncovered during more extensive earthwork excavations. (meaning that the site is covered in concrete of various thicknesses and testing was not possible where there are underground structures).

What they found from historical and recent surveys:

The historical investigations found odours and staining in Chalk fractures in the deep boreholes, predominantly in the south of the Site and at depths between 15 m and 20 m bgl. This contamination appears to have originated from tarry contaminated material used to infill gas holders 1 to 3 in the south- west corner of the Site.

The soils from the multiple phases of investigation have been compared to up-to-date generic assessment criteria (GAC) for a residential with open space use. A total of 417 samples from across the Site were screened and the parameters exceeding the GAC are limited to benzo(a)pyrene (13 samples), lead (14 samples) and asbestos (19 samples). The soil quality information shows that the area where the most elevated chemical concentrations was detected was the fill material in gas holders 1 to 3 in the south-west corner.

The Chalk is a Principal Aquifer and groundwater monitoring has measured the groundwater level to be approximately 20.5m to 22.5m bgl. The inferred groundwater flow is to the south and towards the English Channel. The groundwater is likely to be saline given the proximity to the coast and the Site is not within a groundwater source protection zone for a potable water supply.

The most recent groundwater sampling round at the Site was undertaken in 2019, which followed eleven previous phases of groundwater sampling dating back to 2001. The 2019 results indicated concentrations of ammonium, sulphate, complex cyanide, iron, naphthalene and benzene exceeded UK drinking water standards and ammonium, chromium, zinc, aromatic hydrocarbons C5 to C7, C10 to C12, naphthalene and benzene exceeded Environmental Quality Standards for coastal waters in three or more samples. The 2019 results are within the within the range of the historical dataset and similar to those from 2016 and 2017. It was acknowledged that residual hydrocarbon and ammonia concentrations existed in the Chalk and the fluctuating concentrations recorded may be attributable to seasonal groundwater level variations. The results supported the continued approach that betterment of groundwater quality by natural attenuation was occurring.

So as we feared, there are elements of cyanide, asbestos, naphthalene and benzene in this ground. Once again it appears that the sensible way forward is not to disturb the most polluted areas and to only allow minimal ground disturbance for building on the rest of the site. It is of concern that Quod/St William suggested that `odour’ should not be included in the planning assessment.

This time the NIMBY approach - 'Not in our backyard’ seems entirely justified!

Resources:

Environmental Impact Assessment Scoping opinion (Nov 2020) - Download the pdf (10 pages)

Environmental Impact Assessment Scoping report (July 2020) - Download the full report (231 pages)