How to get rid of unwanted fat: Part II
And with bad practice costing millions of pounds a year, it is an issue which is currently being addressed by many of the UK’s water and sewerage companies; the industry’s trade association, British Water, included (http://www.bwfog.co.uk).
Ask any drainage engineer about their biggest drain blocking bugbear and once you have been treated to a list of the most interesting items disposed of down sewers (household items, toys, dead dogs, false teeth), inevitably you’ll find ‘FOG’ up there near the top.
Lost in the fog
FOG is the inoffensive sounding acronym for what is a particularly nasty combination of waste products. Somehow it sounds less tangible and certainly less damaging than the reality, which is a lethal (for sewers) cocktail of fats, oil and grease.
FOG is reported to be responsible for a staggering 75% of the 200,000 or so sewer blockages that occur every year and for which costs run into the millions of pounds. Anglian Water, for instance, estimates the cost of blockages in its region alone to be £5.8 million.
Operations director of the Lanes Group, Alan Wallis, says it is easy to blame fast food outlets and the like:
“You would expect the main culprit in this to be the massive food services industry, though many catering establishments are already on side in their approach to the problem, having invested heavily in FOG prevention with grease traps or enzyme dosing systems, or both. Some of our key accounts in that sector actively sit on industry forums helping to formulate best practice documentation. Some also have their waste oil collected and recycled into bio diesel. Certainly businesses are easier to police via legislation such as the Water Industry Act 1991; Environmental Protection Act 1990 Statutory Nuisance; Building Act 1984 and Food Safety Act 1990.
“So the problem is not all about fast food outlets and five star restaurants. Domestic users are culpably careless when it comes to washing food waste down the sink and, whilst they might individually contribute only a fraction of that produced by, say, a food business, collectively householders are a serious problem; and one which has to be tackled, either by preventative or remedial means.”
So what do we do? Stop them from doing it in the first place? Or put in place a programme of regular sewer cleaning and FOG build up removal to keep the systems flowing? Prevention or cure?
Education, education, education
Severn Trent Water (STW) is taking the prevention path. The utility company currently manages around 22,000 sewer blockages a year, with Burton-on-Trent apparently the worst offender in its region. As a result, STW has launched a £5 million campaign aimed at schooling its users in the finer points of sewage system disposal — and that includes staff going door to door in some areas.
Naturally, when confronted, no one admits to the heinous crime of inappropriate waste disposal — one resident apparently spreads her FOG onto bread and leaves it out for the foxes (who are now, presumably, suffering from high cholesterol). Yet an engineer speaking on a news item featured recently on ITV Central estimated that 8 out of 10 sewers in the town would be blocked at any one time, thanks to FOG — “mostly” — and to other items like sanitary products, wipes, and other so-called ‘flushables’.
People seem to be clueless when it comes to what is and is not acceptable practice, so need to be told. Too often the warning not to put fat, oil and grease down the drain comes as something of a revelation (“It does what?”). Should we not all know by now that FOG clogs up our pipes much as cholesterol does our arteries?
Or that it matters not how freely liquid fat will flow down the plughole: once it hits the cold sewer wall, it turns into a frighteningly solid mass — often forming soap-like stalactites in the pipe. Over time and with accumulated similar matter, it sticks, attracts more debris, and the flow in the pipe becomes restricted. The rest, as they say, is history.
But the result is blockages and sewers backing up for the users; and a whole heap of complaints for the utility companies; not to mention disaster if the dreadful stuff gets as far as the wastewater treatment works. FOG can deposit inside sewage pumps, where it may restrict cooling thereby causing pumps to overheat and trip out. Clearly there are consequences above and beyond an increased propensity to cause back ups and flooding; not least that it creates a secondary health hazard as a food source for vermin.
Calculate the costs
For the water companies, the prevailing and underlying worry must be a monetary one. Costs involved in remedial work to keep the dreaded FOG at bay can mount up because, for one thing, once it is there, it is exceedingly hard to remove. Ordinary high pressure water jetting may be ineffective so that the congealed fat has to be sliced away using forward-facing cutting jets instead.
This allows operators to break through the dense matter and break the chemically reacted FOG (named ‘FOGc’ by the UK FOG Forum) to be broken down into manageable chunks. Yet that is not the end of it. The content has still to be vacuumed out of the drain or sewer using specialist jet vac tanker units and taken to a registered waste site for disposal. It all adds up.
Who owns the problem?
On top of that, there is the thorny question of liability too. With last year’s legislation transferring around 200,000km of privately owned sewers and lateral drains to the care of the water companies, much of the responsibility for clearing the offending material from our sewers will fall on the shoulders — and pockets — of the utilities.
Let us hope those pockets are deep and that those who authorise expenditure have long arms. Figures of up to £20 million per annum have been suggested as the total cost of the FOG nuisance to drains and sewers, even before the private sewer transfer in October 2011. These estimated costs are made up of blockage removal, sewer or pumping station cleaning, clean-ups and compensation following any subsequent flooding and associated pollution events. Reporting, though, is hazy at best; and there does not seem to be data available for private or insurance funded work, so the actual financial bottom line is an unknown.
A FOG strategy for all
Over recent years, some WSCs have taken a proactive approach by cleaning main sewers if they traditionally have had FOG blockage problems in an area previously. This is also, technically, ‘prevention’ rather than ‘cure’ — keeping the pipes free-flowing by regular cleansing and jetting is obviously a step in the right direction.
Alan thinks that perhaps any FOG strategy has to be three-pronged:
“Education is obviously important to try and keep FOG out of the sewers in the first place — that’s the prevention bit. But if we cannot rely on everyone to comply with instruction, water companies must be ready to react swiftly with a ‘cure’ when the sewers do become blocked with the dreaded FOG. Meantime, a programme of preventative maintenance cleaning provides a ‘halfway house’ between prevention and cure. And that should go someway to keeping everyone happy.”
If you’re seeking a solution to sewer related problems then contact your local Lanes Group depot on 0800 526 488.