With water in desperately short supply this year, an experienced engineer has warned that a proposed new development in Brighton could seriously affect the city’s water supply and waste tonnes of water each year.
Dr James Rhodes, a research and development engineer and senior numerical analyst, said the proposal to build a new Royal Mail sorting office on top of an aquifer in Patcham, could have a negative impact on Brighton’s water supply and waste thousands of litres of water a year. He believes rain, which would have soaked down into the aquifer naturally, will instead be collected in a tank on the proposed site and drained straight into nearby sewers.
The Royal Mail plans to move both its Brighton and Hove sorting offices and develop the site at Patcham Court Farm on Vale Avenue in Brighton to house them. However, the city’s drinking water supplies originate in the chalk around Patcham Court Farm as water gathers below the farm in an aquifer, or water-bearing rock system, that extends across the South Downs and the National Park.
Brighton and Hove’s water supplies flow through this aquifer and the naturally filtered water is then collected in Victorian tunnels, known as adits. These tunnels are linked to Patcham Pumping Station in Waterhall. This water is processed and drinking water is sent to Brighton and surrounding areas.
In winter when it rains, groundwater rises from this aquifer, occasionally flooding homes nearby. This is likely to be aggravated by building on the permeable farmland of Patcham Court Farm. Despite this issue, the Royal Mail wants to erect a large sorting office, car park and water tank on the aquifer. The Royal Mail will then collect, and dispose of, the excess water. 350 staff will be using the site throughout the day, with HGVs entering the site seven days a week, twenty-four hours a day.
Dr Rhodes said the Patcham Court Farm development could adversely affect Brighton’s water supplies: “Development on this site will mean that water that would otherwise have gone to the aquifer, will have to be collected and thrown away. It will reduce Brighton’s possible available water supply now, and in the future, and millions of gallons of water will be wasted. Under the proposal all rainfall from the 1.3 hectares of land will be stored and directed to the sewer at a rate of 5 litres per second. This means that for every millimetre of rain, 13 metric tonnes, or 13,000 litres, will literally be thrown away. It is hard not to imagine what this could amount to in a year. By contrast a garden hose uses between 10-15 litres per minute depending on water pressure, so consider how much water will be wasted. Of course, hosepipes have been banned in Sussex because it’s important to conserve water.”
Rebecca Kimber, who is co-ordinating the Patcham against the Royal Mail community campaign, said: “We’re experiencing the driest year on record since 1935, so it’s nuts for Royal Mail to tarmac over a natural water system at this time. The strain on our water supplies will only get worse with climate change and this development will waste drinkable water and reduce Brighton’s water supplies. We need to be protecting our natural water systems for future generations.”
Dr Rhodes explained: “During the winter months some rainfall percolates down to the saturated layer within the aquifer. The interface between the saturated and unsaturated zones is known as the water table which at first rises slowly but gains momentum as rainfall continues becoming ever closer to the surface. The rain that seeps into the ground is also accompanied by surface water from less permeable areas. Consequently, there are occasions when the two meet up, sewers become inundated, and the village is flooded. When this happens, I feel sure that the residents would prefer not to have 18,000 litres per hour of additional water being added to the problem.”
Dr Rhodes added the weight of the development could also affect the hydrology and the geology of the site: “The area is described as the ‘Patcham Fault and Cave System’ so the weight of structures placed upon it need to be considered very carefully, as well as the impact they may have on others.” According to Dr Rhodes there are two large fissures, as well as the cave system on Ewebottom Hill and a collapsed cavern on the western flank of the former farm.
Plans to develop this site had to be abandoned before because of the proximity to the water supply. Currently the government’s Groundwater Source Protection Zones rate the proposed site at Patcham Court Farm, as Zone 1. This is the highest rated groundwater protection zone. It is also part of the Drinking Water Protected Area and the Inner Source Protection Area. Previously Brighton’s water supply was protected by the Brighton Corporation Water Act which was passed by an Act of Parliament in 1924.
Apart from the threat to Brighton’s water supply, residents are also worried, this development will have a detrimental effect on all residents, particularly children. They believe it will also adversely impact local shops and businesses, commuters, Patcham’s historic village, and endangered wildlife species living on the site. If the proposal goes ahead, it will mean:
- 350 staff will use the site throughout the day with HGVs entering the site seven days a week, twenty-four hours a day. Some streets in Patcham do not have pavements so extra traffic could endanger the lives of pedestrians, particularly children walking to and from school, especially as the Royal Mail Shifts are believed to end at 3pm when schools close.
- An enormous rise in air pollution will cause respiratory problems, including asthma in young children. There are six schools in Patcham and, as yet, the Royal Mail fleet is not electric, nor is there a set date for these new vehicles to come into operation.
- A massive rise in noise pollution throughout the night, seven days a week, which will cause sleep deprivation for all Patcham residents.
- A staggering increase in congestion as there will be a substantial increase in traffic entering and leaving Brighton. There are already long queues of traffic along London Road, and near the bypass roundabout. This is even worse at weekends and in holiday periods.
- A major rise in traffic congestion in the village and insufficient on-site staff parking in an already over-crowded area, making it impossible to park near local homes and local shops, putting local businesses at risk.
- Increased village traffic could endanger residents, particularly those living in sheltered accommodation on Ladies Mile Road, as well as children going to school, as there are no traffic lights or Pelican Crossings in the centre of the village.
- A significant loss of habitat for protected and endangered species at the former farm, such as slow worms, adders, beetles, hedgehogs, badgers, bats, deer, sparrowhawks and other birds of prey.
- If excess water in winter is prevented from sinking back down into the aquifer, the water could flood the historic old village at the foot of the hill. The nearby railway line could also be affected by excess flooding. Flooding may also affect the Preston area.
- This development will destroy a quiet residential area and adversely impact the conservation area in Old London Road.
Planning notices were posted on the 5th of August so the period for objections has been extended. Objections to the proposal must be submitted to Brighton and Hove City Council by 26th August 2022.
Note for editors:
The aquifer (water bearing rock) system at Patcham extends across large parts of the South Downs and the National Park. It supplies naturally filtered drinking water across the area. Since the 1950s the whole system of water collection from the aquifers was integrated, allowing control of the entire catchment area within the Brighton Block. The Brighton Block is that part of the chalk outcrop which exists between the rivers Adur and Ouse and forms the aquifer referred to.
The Patcham Pumping Station, which has several major adits, sometimes referred to as horizontal shafts, was designated as a "Storage Station" at that time, so that during the winter months most water would be pumped via designated leakage stations near the sea and rivers, leaving the storage stations to provide water in the summer months when the water table was low.
Patcham Court Farm on Ewebottom Hill is joined to the eastern adit of the Patcham Pumping Station via a large fissure which was breached as the adit was pushed further eastwards. As the water table rises, the fissure allows water in the saturated zone to transfer rapidly to the adit, as well as providing direct access from the surface, which could potentially be contaminated. As Patcham Court Farm is close to the abstraction adit, it makes it very difficult to prevent contaminants introduced onto the surface by development.
The proposed development site, Patcham Court Farm, is rated a Zone 1 SPZ. This is the highest rated groundwater protection zone. It affords this high rating because on this part of the hill, pollutants can enter the water stores beneath at the fastest rates and pollute the pumping station. This is due to the unconfined and porous nature of the Seaford Chalk that is just beneath the soil. It is also part of the Drinking Water Protected Area and the Inner Source Protection Area.
Patcham’s drinking water
The aquifer beneath the hill is a porous rock from which Southern Water extracts water. This water reaches the Waterhall Pumping Station through a series of adits which run deep underground to the bore hole in Mill Road.
The adits link other aquifers in the system on the downs and water collected from all of these is then pumped from the Waterhall Pumping Station to our taps and to the homes of people in the wider city. In fact, at times, it provides water for up to 380,000 people as far out as Peacehaven. This water comes from the aquifer system and its natural purification system. The hills also provide the water pressure in our homes.
The water quality is already a cause for concern with higher than recommended Nitrate levels and the development on Patcham Court Farm could further influence the water quality as it is in a downward quality trend.
In 2005 when a Park and Ride scheme was being planned for the farm and allotments, a Southern Water spokesperson, Paula Jackman, confirmed that 17.5 million gallons of water were licensed to be pumped daily from Patcham's groundwater supply. At times up to 46.5% of the daily requirements of every person in the city. Since then, the city population has grown and with it the amount of water required.
If the water in the hill becomes contaminated with pollution, it CANNOT be pumped from the hill to residents. In reverse the pumping station CANNOT take water away back up into the hills if there is heavy rainwater and the groundwater rises! This leaves the village and surrounding areas at greater risk of flooding more regularly and with greater consequences.
Back in 2005 when the council were investigating potential Park and Ride sites for the city, Patcham Court Farm was considered and assessed for a car park with a single storey on the North Side. The resulting report makes interesting reading about the hydrogeology of the site and describes the farmyard as being located over a major aquifer.
It was determined that the natural soils would be suitable founding strata for a lightly loaded structure associated with park and ride, but that excavation was thought to be at high risk of discovering the presence of solution features such as sink holes. One such sink hole was discovered on the west side of the farm when the ground was cut through for the bypass.
Patcham Village, which is a conservation area, is liable to flooding. This is because the underground river, the Wellsbourne, begins at Patcham and runs down from the hills. The Wellsbourne is a winterbourne which once flowed seasonally down the valley, through Preston to the sea, before exiting through Poole Valley. After heavy rain, significant flooding can occur but pumping water out of the Aquifer largely prevents the chaos such floods would cause.