With the news that Windermere lake has tested positive for the presence of blue-green algae at the start of school summer holidays, you might be asking yourself “How does this happen?” At Hutchinson, we’re interested in the wider impact of sewage pollution, so our Technical Manager, Paul Usher, has done the research for you.
The Lake District National Park website gives a pretty succinct description of what blue-green algae looks like and how it can affect people and animals. I can vouch for the greenish appearance of the water, the earthy, slightly musty smell and the eye irritation: I was learning to paddle-board on Coniston lake about a week before the Environment Agency announced the presence of the algae. On one of my many trips into the water I do remember thinking “This smells unusual” - I swim with my kids regularly in Coniston, too, so I have a point of reference – and, on one occasion, opened my eyes underwater for some reason and saw that the water did have a greenish hue through the sunlight. The eye irritation lasted about 3 days. I’ve not suffered any other ill-effects though, despite some fairly alarming headline warnings about potential toxicity and swallowing at least one mouthful! That said, I’ve not been in the lake since the warnings were issued on 5 July, and I won’t be going in again until the all-clear’s given.
As a sewage treatment specialist with nearly 20 years’ practical and theoretical experience of septic tanks, drainage fields and package sewage treatment plants, I know what’s in wastewater, both treated and untreated, and how it affects the environment in ways that can’t be seen with the naked eye. A sales rep at Klargester, where I worked for some years, used to try to seal a sale by telling potential customers that the liquid coming out of a Biodisc was “as clear as gin” – and he was sometimes right, it could be. Potential customers often inform me that the discharge liquid can, in fact, be drunk, because that’s what they have been told by sales reps from potential suppliers. No rep that I know has ever stood by those words, words fuelled by eagerness to hit a bonus trigger point for the month’s sales figures. (Yes, like “tied” financial services providers, sewage treatment plant manufacturers incentivise their salespeople to promote their own products. Unsurprising, we live in a commercially-focused world, but think a moment: if you were going to invest £8-10k on a new sewage treatment system for your house, or £100-200k on one for your caravan park, wouldn’t you want independent advice, in the same way that you’d absolutely look for it if you were investing similar sums in a financial product?)
So, what is in wastewater, and how does it promote algal growth, or “blooms” as they tend to be called in the industry? The answer is “nutrients”.
We know that farmers spread “muck” on their land to improve its productivity, to make grass and crops grow: “muck” is a fertilizer, it contains nutrients, specifically nitrates and phosphates. Human “muck” contains those nutrients, too. If conditions are right – there’s enough food, water, oxygen and light – plants will thrive. Although algae aren’t strictly speaking plants, they need those same conditions to grow. And in nature there is almost always a “limiting factor” for growth, a lack of one element or condition that is essential for life. In a lake that’s obviously not water, and it’s rarely light (or warmth) or oxygen; sometimes it’s nitrates but most often it’s phosphates. Phosphates have been called “the spark of life” - they are essential to all living things. Interestingly, and unlike many other essential elements, phosphates – or more strictly speaking the element Phosphorus (P) – cannot be synthesized or manufactured chemically: it is a finite, and relatively scarce, natural resource, and it’s expensive to refine.
The Environment Agency obviously realise the importance and manages the impact of nutrients on any “receptor” - the place to which treated wastewater is discharged. It’s the Environment Agency that sets the parameters of any environmental permit issued to anyone discharging treated wastewater, be it United Utilities, Northumbrian Water, Scottish Water or Mrs. Smith of Rose Cottage. It’s known through study and research that Windermere lake is “P sensitive”, that is, there are almost sufficient phosphates in the lake at any one time to spark life; this is why United Utilities have had to invest hundreds of thousands of pounds on their treatment works in Ambleside and Windermere.
Unlike “muck”, though, phosphates and nitrates can’t be seen when dissolved in water, in the same way dissolved sugar can’t be seen in tea. So while the treated effluent might well be “as clear as gin”, it doesn’t mean that it’s pure and not having a detrimental impact on the environment, to say nothing of the viruses and bacteria that can’t be seen, either. If a sales rep tells you that you can drink it, invite him to do so. It is not Evian.
So, as the owner of a sewage treatment system from which the discharge somehow makes its way into Windermere lake, Coniston lake, Derwent water or Killington reservoir – the 4 affected “receptors” in Cumbria – how can you help to stop this happening?
Firstly, have your septic tank or package sewage treatment plant desludged or emptied regularly. Phosphates are retained in the settled sludge by adsorption: they “stick” to other molecules because of a differential electrical charge. But once there are no more molecules left with an attractive electrical imbalance the phosphates have nowhere to go but out of the tank and into the wider environment, where plants – and algae - will take them up. And if your tank is too full of molecules, of any type, they will start to flow out into the environment.
I was told again yesterday, four times on four site visits, that there is no need for septic tanks to be emptied: that’s par for the course, once on almost every site visit, usually backed up by “I’ve not had my tank emptied in 10, 20, 30, 40, etc. years and it’s never caused a problem”. To which my response is “Not that you’ve seen, or had the knowledge to understand the biochemistry involved in either the nitrogen cycle or the phosphate cycle as it relates to wastewater treatment and its environmental impact”.
If you own an off-mains hotel, B&B, caravan park, campsite – anywhere that relies on tourist income - near Windermere. Coniston or Keswick, and your guests complain about not being able to enjoy water sports during the school summer holidays because of the algal blooms, and that next year they’ll go abroad despite the great weather we’ve had this year, think a little about what happens to your wastewater and how it’s treated. Have you shot yourself in the foot, maybe? Or your neighbours? Do you need to get your tank emptied more regularly? Ask us about how often “regular” is.
Secondly, if you have a drainage field or “soakaway” and it sometimes gets waterlogged, or your drains are sluggish, or it’s close to a beck, river or a lake, have it checked out. It won’t be cheap, I’m afraid, but neither’s lost revenue to your business. We’ll do a non-invasive check for nothing.
Thirdly, if you have a package sewage treatment plant, make sure it’s working as well as it can do by keeping it in good condition. Have it serviced regularly – once a year for a small one serving a 1, 2 or possibly 3 houses, up to 4 times for one serving a caravan park with hundreds of pitches – by a company that not only offers electrical and mechanical competence but one that understand the biochemical processes that are supposed to happen in the treatment plant, otherwise you are literally throwing your money down the drain.
Finally, if your septic tank discharges to a beck, either directly through a straight pipe, or indirectly through an “overflow” pipe from a drainage field, you are required, by the law of the land, to stop that discharge before the end of 2019 and sooner if it’s polluting – which, if you’ve got this far, you’ll know it is regardless of how clean the discharge may be…