A WATER company is on the verge of completing a major upgrade of the city’s sewage network. Jeff Travis went to visit Fort Cumberland, which has been at the centre of a controversy over unscreened sewage being released into the sea.
It’s been an ongoing saga that has angered beach goers, walkers, nature lovers and politicians.
Sanitary items strewn across the shoreline is a sight that understandably disgusts some people, especially when it is at the two of the area’s gems, Langstone Harbour and Eastney beach.
The culprit for this environmental blight has been Fort Cumberland at Eastney – where the screens that are supposed to filter the city’s sewage were damaged in a massive storm in 2010.
Time and again officials at Southern Water have said the discharges prevent Portsmouth and surrounding areas flooding and, after all, the effluent is heavily diluted with rainwater.
But these statements have provided little comfort to complainants such as Eastney Cruising Association, where members have had to wash sewage items from boats and even cancelled a swimming regatta this summer.
However, it now appears there is a light at the end of the tunnel.
After an investment of about £13m, set to be completed early next year, the problem should become a thing of the past.
I am given a tour of the Fort Cumberland site, a sprawling site at Eastney, to see the improvements for myself.
The sheer size of this place and the acres of storage convince me very quickly that dealing with sewage from about 400,000 homes is no easy task.
Paul Kent, wastewater strategy manager for Southern Water, explains: ‘Unfortunately in 2010 the site was hit by a significant storm which damaged the screen and stopped it working.
‘We have spent the time since then figuring out what we are going to do.
‘The last thing we want is to put a sticking plaster job back because sooner or later another storm is going to damage it and we are back to square one.
‘We didn’t want to just put a different screen in.
‘We have spent time thinking about an appropriate solution.’
Understanding the changes is a bit of a technical labyrinth, but the upshot is that Southern Water has spent the last four years masterminding a new way of working at Fort Cumberland.
New screens have been put in and the way sewage flows through the system has been changed to minimise the chances of any unsightly items ever getting into the sea.
The pumps and electrical equipment at Eastney have also been refurbished, thanks to a £3m investment.
‘They are completely replumbing,’ says Steve Fastnedge, who is the site manager and works for 4D, which is contracted to run the site.
‘We have looked at the design of this place.’
One of my burning questions is why it has taken so long to get the problem fixed, considering the financial resources of a company like Southern Water.
Mr Kent explains: ‘What makes that task more difficult is this remains a live site.
‘When the storm tanks are full you can’t work on them.
‘Once the storm passes, you then have to clean out the storm tanks so you can work in them again. This last six weeks has not been kind to us.
‘It’s taken more time than we would like to get where we are and we are due to finish in the spring of next year.’
Mr Kent was apologetic about the discharges, but added: ‘The majority of it is rainwater – it is diluted. It’s not as dramatic as it’s made out to be. Because the screens aren’t working, sanitary items do get out there.
‘After each event, we go and clean the coastline as best we can to remove those visible items.
‘It does happen, but that won’t happen once the site is finished.
‘You will still have discharges because you need to relieve the system – if you can’t relieve it, the flow has nowhere to go.
‘Those sanitary items will be removed here and won’t end up on the coastline.’
He adds: ‘It’s not been an easy scheme to deliver. We have done it as fast as we can to provide a long-term lasting solution. We would not be thanked by anyone if six months later it failed again.’
Three years ago Southern Water was fined £150,000 for a number of illegal discharges in Langstone Harbour. But company officials are confident that a corner has been turned to stop such pollution incidents happening again.
Asked whether Southern Water cares about the environment, Mr Kent adds: ‘It’s what we are about. Look at bathing water around the south east of England.
‘Twenty years ago less than 50 per cent of those bathing waters passed the standard. It’s now 100 per cent and it’s 100 per cent because we have invested hundreds of millions of pounds building Budds Farms.
‘We definitely do care about the environment.’
- One of the first sewer networks built in the country, the Victorian sewer network is made up largely of combined drainage – surface water and foul.
- Wastewater from the Portsmouth catchment is treated at Budds Farm – Southern Water’s largest waste water treatment works, serving more than 400,000 people and treating 109m litres of waste water per day.
- In September, approximately 640 tonnes of rag (solid matter) was removed from Budds Farm – the equivalent of 400 hippos.
- During storms the system can quickly be overwhelmed – dry weather flows are less than 1,000 litres per second, during storms this increases to 20,000 litres per second or more.
- Low lying Portsmouth is the most densely populated city in the UK outside London.
- In Portsmouth, between January and September, there were 172 blockages caused by things that should not be in the sewers – mainly fat and wet wipes.
Sewage in the city - a layman’s guide
UNDERSTANDING the nature of the sewage issues comes down to Portsmouth’s unique situation as an island city with a Victorian sewer network.
More than a century ago the city’s sewers, some of the first in the country, were only ever designed to be a drainage system.
The waste was pumped out to sea, no questions asked.
But times have moved on and all the sewage now flows down from the mainland and down through the city to Eastney Pumping Station.
Because there was never enough space on Portsea Island to build a treatment plant, a two-way five-mile pipe was built to Budds Farm in Havant in the mid-1990s. Untreated sewage gets pumped to Havant, is treated and then pumped back to Eastney and through the long sea outfall three-and-a-half miles out at sea.
On a rainy day, the storage tanks at Fort Cumberland are needed because of the sheer quantity of rainwater from the whole region.
This water is stored in storm tanks with a total capacity of 40,000 cubic metres.
The sewage is stored there until it can be pumped back to Eastney Pumping Station and sent under the harbour to Havant to be treated.
The big problem arises when there is a huge storm and hours and hours of heavy rain.
Almost akin to a tsunami, the flow from the sewers can increase rapidly by 20-fold.
Storm tanks at Fort Cumberland are overwhelmed and some diluted sewage is allowed to be screened and released out to sea to stop the system backing up and the city flooding.
For the last four years, that overflow has not been screened, leading to the complaints.
But a subtly sophisticated new system should stop any sanitary items getting into the sea.
Engineers from Southern Water and 4D, the site contractor, have put the new screens at the end of four storm tanks.
Whereas before the fast-moving stormwater would hit the screens first and then go into the tank, the sewage now has to pass through four tanks.
This means that any solid material – called rag – will have chance to settle in each of the tanks as it passes through. By the time the sewage reaches the fourth chamber, the flow will have slowed down considerably. Any solid matter remaining will be screened through quarter-inch holes and Southern Water officials believe virtually nothing will find its way into the sea.
The new system reduces the chances of the screens being damaged in future.
Paul Kent explains: ‘If you can imagine the flow coming to you as a wall of water, that hitting a piece of mechanical, electrical equipment can knock it out.
‘So we have put it at the other end of the process. We are taking the momentum out of the flow to protect those screens.’
In addition, a surface water separation scheme, costing £20m, is nearly complete to build extra capacity into the sewers across the city.
The idea is instead of mixing rainwater with sewage, the clean rainwater drains directly from the roads into its own pipes.
The rainwater is then pumped directly out to sea.
By installing new sewers, it will reduce the storm water flowing to Eastney by about a third.
Engineers reckon this, together with the more efficient system at Fort Cumberland, will ensure that consented discharges into the harbour will happen rarely.
And if they do, the sanitary towels, wet wipes and cotton buds will be screened out.