CASE STUDY (1) NW ENGLAND & WALES

3.2.1 Sources and pathways – Industrial estate surveys in Merseyside

The problems are not new. The importance of industrial estates as intractable chronic pollution problems was recognised by the former North West Water Authority in a report in 1984, investigating water quality in the River Mersey and tributaries and the adjoining catchment of the River Douglas, in NW England (D’Arcy et al. 1984). It was a detailed study and reported here since it is probably still very relevant in most countries where waste storage and diffuse pollution legislation has not been established and enforced. Table 3.4 summarises water quality and impacts for one of the most severely impacted streams in that intensive survey (Kirkby Brook).

Table 3.4 Organic pollutants in drainage from Kirkby Industrial Estate (Kirkby 72 inch surface water outfall) in 1984, and impacts on stream quality.

Kirkby 72” SWO into Kirkby Brook BOD5 COD

Mean concentration 138 mg/l 354 mg/l

Max. concentration 1120 mg/l 1790 mg/l

Min concentration 12 mg/l 75 mg/l

Estimated load 152 kg/d 539 kg/d

Kirkby Brook Watercourse originates

It is important to note that the data in Table 3.4 above was compiled as part of a programme of intensive (weekly) visits to potential sources on the estate in a systematic effort to resolve pollution problems. The work demonstrated that diffuse pollution is not able to be solved by the approach taken then of just putting bund walls around oil tanks and diverting contaminated areas to the foul sewer.

Twenty-two industrial estates were identified for assessment by biological sampling above and below their surface water drainage discharges into the receiving watercourses, as exemplified above in Table 3.4 for Kirkby Industrial Estate. In most instances there was a deterioration in quality below the estate, or the quality was poor and the watercourse originated close to the estate. The survey results are summarised in Table 3.5.

Table 3.5 River quality below industrial estates in Mersey-Douglas catchments,

Class 1 downstream (d/s) None Only 1 site where upstream (u/s) quality was 1 (d/s was 3)

Class 2 downstream 2 Aesthetic issues (oil) in both cases, but no class change

Class 3 downstream 10 1 site had improved from class 4 previous year Class 4 downstream 7 1 site had deteriorated from previous year All drainage diverted to

foul sewer prior to survey

1 Compromise action to try to stop river pollution No data obtained 2 Watercourse unsuitable for biological sampling Source: Summarised from D’Arcy et al. (1984).

The 1984 biological survey (Table 3.5) was undertaken following a period of  several years of intensive investigations to try to achieve improvements (Table 3.6). The biologists remarked that although the rivers and streams remained in the lowest pollution class category, there had been a very clear improvement in visual appearance of many of the watercourses. But gaining class improvements obviously required more than just ‘housekeeping’ measures such as storage bunds and clean-up actions.

Table 3.6. Summary of the findings for 6 different estates.

Industrial

1 2 22 Oil, toxic metals, foam, suspension, paint

2 3 23 Oil, foul smell, sewage fungus, turbidity, acid

3 1 27 Oil, discolouration, toxic metals

4 Several Many Oil, dyes, turbidity

5 2 24 Oil, cyanide, acid, smell, discolouration

6 2 7 Oil, discolouration

Table 3.7 summarises the contaminants and pathways for pollution identified in the Mersey-Douglas investigations. Similar problems have been found in similar investigations elsewhere (D’Arcy & Bayes, 1995) and there is little reason to expect anything different in other countries unless pollution prevention measures and sustainable drainage systems (SUDS) (CIRIA, 2015) or urban best management practices (BMPs) (United States Environmental Protection Agency [USEPA], 1993) have been provided. In the years since that baseline study, in the UK there has been a succession of new laws and powers to control

Industrial estates as sources of water pollution 43 and prevent pollution, especially associated with the EU Water Framework Directive and the parallel Waste Framework Directive. A repeat of the 1984 survey would be useful to assess the effectiveness of those measures, since waste storage outdoors has been changed as a result and should be reflected in water quality improvements with lessons for mitigation plans elsewhere and catchment management programmes. The basis of river quality classification has also changed, but comparisons could still be made since the former methodology is published and still available.

Table 3.7 Causes of surface water contamination identified in surveys of industrial estates.

Type of Industry Example Pollutant Pathway for Surface Water Contamination Corroded feed pipes from stock tanks Corroded steam pipes from heavy fuel oil

Cable manufacture Cadmium, copper Dust (from air filters) stored in open drums outdoors (open to rainwater leaching metals)

Breweries Yeast, beers, fob (foam), waste beer

Spills from road tankers at loading bays, pressure release valves, can crushing plant in open yard Breweries,

distilleries, animal feed industry, granaries

Fermenting grain Wind-blown grain from unenclosed off-loading/handling areas, carried by

Unbunded tanks, filler points, leaks, spills, corrosion

Food processing Molasses, flour, sugar, other highly degradable materials

Pipe bursts and valve failures, leaks, brushing out spilled materials from burst containers in vans/wagons

Vehicle washing to surface water drainage system

Source: From D’Arcy et al. (1984).

3.2.2 Deepols – potable water supplies at risk

North West England provided another classic example of industrial estates as a significant water pollution problem, also in 1984, when drinking water contaminated with phenol was distributed to some two million people. The public potable water supply was the River Dee, which arises in North Wales and is abstracted upstream of Chester, NW England, for treatment and distribution there and to Merseyside and beyond. There had been a spillage of phenol at Wrexham industrial estate in North Wales which polluted a tributary stream which in turn contaminated the main river. The water treatment process included chlorination, which did nothing to reduce potential health risks of contaminants, but did give a strong readily recognised taste to the water (di-chlorophenol is the distinctive flavour of medicinal disinfectant TCP; present as well as the main constituent, trichlorophenol). That incident raised awareness of pollution sources and risks across the catchment. In particular, it highlighted the risks of industrial estate contamination of surface waters, by polluted runoff, not just licenced effluent discharges (see D’Arcy et al.

2000). Sadly, it was not a unique incident, and a thorough analysis of risks and implementation of continuous monitoring has produced an extensive database of contamination evidence – ‘Deepols’ (Figure 3.1). Episodes are classified in three categories, from high risk (1) down to low (3), and a fourth category records contamination data as precautionary evidence.

Industrial/commercial Agriculture Permitted Natural Traffic Other Error

54 28 32 34 18 5 10

0 10 20 30 40 50 60

1 2 3 4 5 6 7

Figure 3.1 Summary of recorded pollution incidents in the River Dee with potential to contaminate potable supplies (‘Deepols’), from 1993–2010; all categories, by type of source (Environment Agency [EA], 2011).

The Deepols evidence indicates the predominance of a large industrial estate as the principal risk, with three times as many incidents (54) as, for example, traffic accidents (18), despite the Dee catchment including sections of major trunk roads into N Wales and the English Midlands. Industrial estate pollution incidents (54) exceeded the number of incidents traced to licenced effluent discharges too (32), or agriculture (28). Other categories established in the Deepols procedure

Industrial estates as sources of water pollution 45 are ‘natural/weather related’ (34) and ‘other’ (5) denoting incidents which were not easily categorised. The catchment is predominantly agricultural, with some uplands and forestry; it is possible the ‘natural/weather related’ is actually diffuse pollution. The seven types of sources are shown in Figure 3.1.

From 1993–2010, there were four serious pollution incidents (category 1, presenting a risk to potable supplies); half of them involved Wrexham Industrial Estate, and they were both involving fires. One was at a site there controlled by a waste permit.

The two other category 1 incidents between 1993–2010 were for an unknown ammonia source, and a low dissolved oxygen condition in the river, cause again unknown.