The utility sector is critical to the way people live in Britain today. The supply of electricity, gas, clean water, and the provision of telecommunications, both phone and internet, are all considered to be essential. INNS have a limited effect on this sector, but they still do cause additional costs to the industry in terms of damage to infrastructure and additional control and clearance costs. Both the water and electricity generation industries are discussed below. No costs to the telecommunications industry due to the presence of INNS were discovered during the course of the research.
12.1 Wa te r In d u s try
One of the main INNS affecting this industry is the zebra mussel (Dreissena polymorpha), one of the most invasive freshwater pests in the world. The annual cost of zebra mussels to industry in North America is estimated to be circa $5 billion (Aldridge et al. 2004) and the costs in Great Britain are rapidly increasing. Although the creatures are smaller than 2 cm, they cling together to form large populations, which can block water pipes and outlet pipes from power stations. Thousands of tonnes have already been found in London’s water pipes, constricting the flow and forcing Thames Water engineers to clear clogged pipes (Observer, October 2006), whilst many other water suppliers use specialist contractors to remove zebra mussel from their condensers each year.
There are 25 main water and sewerage companies supplying England and Wales and one in Scotland (covering 8 million ha). In England, the largest company by population served is Thames Water, which covers an area of 1.2 million ha. Bristol Water, covering an area of 1,500 ha, reported costs of £21,750 per annum for management of invasive species including weeds (<1 %), mink, signal crayfish and zebra mussels. Northumbrian Water spent
£44,775 annually on the management of INNS, and Anglian Water, covering 2.7 million ha, spent on average £75,000 per annum on controlling zebra mussel. Oreska and Aldridge (2010) have calculated that the cost of zebra mussel alone to the water industry is £551,400 per year. There are approximately 361,402 km of water mains in Scotland, England and Wales. Using an average cost per km from the three water companies above (£2.61), the water industry spends approximately £943,259 per year on controlling INNS.
These costs, however, do not include any one-off costs from zebra mussels that may be caused by biofouling. Water intake structures for municipal, industrial and hydroelectric plants are highly vulnerable to fouling if they draw intake water from an infested water body.
In Northern Ireland, zebra mussels have blocked water intake pipes at Killyhevlin water works in Enniskillen and modifications were needed at a cost of over £100,000 (Maguire and Sykes 2004). Anglian Water has included mussel traps in the design of one system at a capital cost of £70,000 (Barrie Holden pers. comm.). Capital spend required for a new zebra mussel control system will be approximately £500,000, and such a control system should last 20 years (questionnaire, P. Bulmer, Bristol Water). Given the period that such a control system lasts, it is likely in any given year that only one such capital project is undertaken by the water industry as a whole, to combat the effects of zebra mussels, and therefore only
£500,000 is added to the annual costs of control.
A further expense to the water industry, this time the sewage network, rather than the mains network, is the presence of brown rat (Rattus norvegicus). The expenditure on sewer baiting for the control of rats was assessed using the proportion of Thames Water’s baiting costs (21.25% of sewers baited), which in 1989 cost £36.88 per km of sewer baited (£42.43 today;
Battersby 2004). If all major sewerage companies bait the same proportion of the national sewerage network (359,763 km), then the cost for Great Britain is approximately £3,243,758 (England £2,641,406, Scotland £448,682 and Wales £153,670.
This gives an annual cost to water companies of approximately £4,687,017 for Great Britain (England £3,816,658, Scotland £648,316 and Wales £222,044)
12.2 P o we r Co m p a n ie s
Virtually all power stations will have INNS problems to deal with from aquatic species like curly water weed (Lagarosiphon major), Chinese mitten crab (Eriocheir sinensis) and zebra mussel (Dreissena polymorpha) that block water intakes, riparian plants, nesting birds, and brown rats which chew electrical cables. Historically, mussels had to be cleared by hand from condenser culverts on a regular basis. Many coastal power stations control fouling by chlorination, whilst in freshwater, where one of the most damaging fouling organisms is the zebra mussel, a variety of approaches are used including heat treatment and the use of intake screens. It has been shown that the single largest return on investment for power plants maintenance expenditure is in condenser cleaning (Conco Systems newsletter, 200876
). Because nuclear power plants use large quantities of water they tend to have the highest associated costs per plant, followed by industrial plants, fossil fuel power plants, and drinking water facilities. Private companies, such as Tube Tech International, use an advanced form of darting technique in the 8,000 tubes of the turbine condenser and reported numerous visits to individual power stations. These routine operations are likely to be costly.
It was not possible, however, to gain any detailed information on these costs from this industry so it is necessary to make an estimate for the 2,615 plants producing in excess of 1 MW in the UK (Digest of UK Energy Statistics, 200577
As discussed in the transport sector, one off costs to the railway industry due to non native tree fall on electricity pylons can prove costly with one incident costing £200,000 in delays and this is included here for England.
). Some stations will spend hundreds of thousands of pounds whilst others spend a lot less. Assuming that each station incurs an average of £2,000 worth of costs per year, then the annual cost to the power industry is
£5,230,000. If this is apportioned by population then the costs to England are £4,497,800, to Scotland, £470,700 and to Wales, £261,500.
12.3 To ta l Es tim a te d Co s ts to S e c to r
The total costs to the sector are estimated at £10,117,000, of which England £8,515,000, Scotland £1,119,000 and Wales £483,000.
Table 12.1. Annual costs of INNS to the utility industries.
England Scotland Wales GB
Water companies £3,817,000 £648,000 £222,000 £4,687,000 Power stations £4,498,000 £471,000 £261,000 £5,230,000
Railway power lines £200,000 - - £200,000
Total £8,515,000 £1,119,000 £483,000 £10,117,000
Re fe re n c e s
Aldridge D, Elliott P, Moggridge G (2004). The recent and rapid spread of the zebra mussel (Dreissena polymorpha) in Great Britain. Biological Conservation 119: 253-261
Battersby JE (2004). Public health policy – can there be an economic imperative? An examination of one such issue. Journal of Environmental Health Research 3: 19-28 Maguire MC and Sykes LM (2004). The Zebra Mussel Management Strategy for Northern
Ireland 2004-2010. Report Queen’s University Belfast. 57pp.
Oreska PJ and Aldridge DC (2010) Estimating the financial costs of freshwater invasive species in Great Britain: a standardized approach to invasive species costing.
Biological Invasions: on-line July 2010