14 NORTHUMBRIAN WATER LIMITED
Introduction
Northumbrian Water Limited supplies on average 758 Ml/d of water to a population of some 2.6 million people in the north east of England. The majority of the Company’s water is surface derived from the rivers Tees, Tyne, Coquet and Wear and from upland impounding reservoirs. The remainder of the water is derived from underground sources, principally chalk boreholes. The water from these sources is treated at 41 treatment works. Treated water is distributed through 249 water towers and service reservoirs and 16,515 km of pipes. The supply area is divided into 111 water supply zones.
Overall water quality
At water treatment works and service reservoirs and in water supply zones, the Company carried out a total of 193,063 determinations in 2000. Of these, 99.88% demonstrated compliance with the relevant PCV, but 230 showed a contravention to have occurred.
Coliforms were not detected at 36 (88%) of the Company's 41 water treatment works. At 248 (>99%) of the Company's 249 service reservoirs, coliforms were absent from at least 95% of samples. Of the Company's 111 water supply zones in 2000, 103 (93%) complied fully with the relevant water quality standards or had breaches of the standards which were either trivial or were fully covered by undertakings. In the other eight (7%) of the zones, some breaches are regarded as unlikely to recur, but others could result in enforcement action.
Microbiological quality of water leaving treatment works
The Company complied with the sampling frequencies required by regulation 17 at 39 of its 41 treatment works in 2000. Shortfalls at the other two are regarded as trivial.
Table 14.1 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. There have been significant decreases over the last three years in the number of treatment works, and samples from treatment works, in which total coliforms were detected. All other differences are not considered significant.
All contraventions of the standards at works are considered trivial or unlikely to recur.
Microbiological quality of water in service reservoirs
The Company complied with the sampling frequencies required by regulation 18 at 248 of its 249 service reservoirs in 2000. Shortfalls at the other reservoir are regarded as trivial.
Table 14.2 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. There have been significant decreases since 1999 in the number of samples from service reservoirs in which total coliforms were detected. All other differences are not considered significant.
Contraventions of the microbiological quality standards at a total of three service reservoirs have resulted in the consideration of enforcement action, as shown in table 14.4. All other contraventions of the standards at service reservoirs are considered trivial or unlikely to recur as remedial action has already been taken.
Water quality in water supply zones
The Company failed to comply with the required sampling frequencies for the trihalomethanes suite in six zones, PAH in one zone and odour parameter in one zone.
Table 14.3 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. There have been significant reductions over the last three years in the number of zones failing to comply with the standard for manganese. All other differences in zones are not considered significant.
Enforcement action is being considered in respect of some contraventions of standards, as shown in tables 14.3 and 14.4. All other contraventions of the standards in zones are considered trivial or unlikely to recur, or a covered by undertakings.
Inspection
Audit of plumbosolvency treatment and control programmes of work
In November 2000, Consultants WS Atkins, represented by Mr M Kimber, working under the direction of Mr P Halton, Inspector, carried out an audit of the Company as part of the Inspectorate’s work in agreeing with water companies’ their programmes of works to secure compliance with new lead standards. Based on Mr Kimber’s report, Mr Halton concluded that:
the Company’s process of sites/scheme selection for plumbosolvency treatment and/or optimisation measures is sound;
the integrity of the data submitted to the Inspectorate and used for assessing plumbosolvency was confirmed;
the schemes audited are justified on water quality reasons; and
the Company’s proposed steps to be taken and the proposed completion dates are generally sound.
Audit trails of five samples
Mr R M Walls, Consultant, working under the direction of Mr W M Waite, Principal Inspector, carried out an audit in November 2000 of five samples for audit trail. Based on his report Mr Waite concluded:
the sampling and analytical arrangements are generally satisfactory. The analytical results may have appeared on the Public Record in time, but the date is not maintained by the database. The Company is taking action to rectify this. Corrections to the public record are not easily discerned and a number of results are presented without a greater or less than sign when this has been appropriate. Several of the control charts have been constructed such that all the results of one day or run are plotted in a column with no information on the order in which they were obtained. Several reporting limits have been set unreasonably higher than the limit of detection.
Mr Walls found contraventions of regulation 29 in two instances and regulation 11(2). However, remedial action was to be taken speedily in each case and so enforcement action was not necessary.
Follow-up of response to recommendations made in 1999 inspection reportsDr K J White, Inspector, carried out an inspection of Northumbrian Water Ltd in December 2000. Dr White concluded that:
the Company had made a positive response to the recommendations made in 1999 inspection reports.
Ms K Parker, Consultant of Binnie, Black and Veatch, working under the direction of Mr W M Waite, Principal Inspector, carried out an inspection of Northumbrian Water Limited in December 2000. Based on Ms Parker's report Mr Waite concluded that:
the Company has made responses to most of the recommendations made in the previous audit of water company procedures for operation and maintenance of distribution systems.
Inspection of distribution system improvement programme progress
In October 2000, Consultants John Champion Ltd, represented by Mr N Jones, working under the direction of Mr P Halton, Inspector, carried out an audit of the Company’s progress with the mains renovation set out in the distribution Undertaking submitted by the Company. Based on Mr Jones’ report Mr Halton concluded that:
the objectives of the undertaking remained valid;
the steps to be taken were defined with adequate precision;
a practicable timetable had been set; and
the Company was likely to meet the target renovation length by the date for completion of the work.
As a result of these inspections, 16 recommendations were conveyed to the Company for formal response.
Improvement programmes
Seven undertakings in respect of improvement programmes accepted by the Secretary of State from the Company were due for full completion or the completion of major steps during 2000 and all of these were completed on schedule.
The ongoing distribution system improvement programmes due for completion in 2010, which have been implemented by the Company, have been progressing satisfactorily.
Relaxations
The Secretary of State had authorised relaxations of the PCV for magnesium in zones supplied by three treatment works and for sulphate in zones supplied by one works, subject to review by 31 December 1999. As a result of the review the relaxations were renewed subject to review by 25 December 2003.
Incidents
Eleven of the events notified during 2000 by the Company to the Secretary of State under the terms of the Water Undertakers (Information) Direction 1998 were regarded by the Inspectorate as constituting incidents in which either drinking water quality demonstrably deteriorated.
Ten incidents have been assessed. Five of these incidents involved the supply of discoloured water following work carried out in the distribution system by the Company. These incidents affected consumers in: Whitley Bay and Monkseaton in March; Ponteland and surrounding areas, also in March; the Marton area of Middlesborough in May; Newton Aycliffe in July; and parts of Teesside in September. Two other incidents also involved the supply of discoloured water. The first affected the Stockton-on-Tees, Darlington and Middlesborough areas in February, and occurred following a burst on a trunk main supplying the area. The second incident involved the supply of discoloured water after a loss of supply from Loftus service reservoir. The three remaining incidents arose following the failure of disinfection systems at Fulwell water treatment works in June, Cockershield water treatment works in August and Murton water treatment works in September.
The Company took all reasonable steps to protect consumers during each of the above incidents and has also responded positively to the recommendations made by the Inspectorate. Following the disinfection failure at Murton water treatment works, and in view of previous incidents at this site, the Inspectorate initiated enforcement action against the Company. The Company has now given a legally binding undertaking to carry out remedial works to prevent any recurrences.
One incident, involving the supply of discoloured water to Langley Park, County Durham, in December, remains under consideration.
No other events regarded as constituting incidents came to the attention of the Inspectorate in 2000.
Enforcement action
Table 14.4 summarises enforcement action under consideration for the Company as a result of the Inspectorate's work in, or pertaining to, the calendar year 2000.
table 14.1 Northumbrian Water Limited
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2000 1999 1998 Number of water treatment works 41 45 48 Works with no sampling shortfall 39 45 45 COLIFORMS Total number of determinations 7,027 7,387 7,672 - number containing coliforms 6 13 38 - % containing coliforms <0.1 0.2 0.5 Treatment works with coliforms detected 5 10 23 - % of all works 12.1 22 48 FAECAL COLIFORMS Total number of determinations 7,027 7,387 7,672 - number containing faecal coliforms 2 6 8 - % containing faecal coliforms <0.1 0.1 0.1 Treatment works with faecal coliforms detected 2 5 6 - % of all works 4.8 11 12
table 14.2 Northumbrian Water Limited
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2000 1999 1998 Number of service reservoirs 249 249 249 Service reservoirs with no sampling shortfall 248 247 249 COLIFORMS Total number of determinations 12,646 12,833 12,953 - number containing coliforms 29 41 58 - % containing coliforms 0.3 0.3 0.4 Service reservoirs with coliforms detected 22 37 49 Service reservoirs with coliforms detected in more than 5% of samples 1 0 1 - % of all service reservoirs 0.4 0 <1 FAECAL COLIFORMS Total number of determinations 12,646 12,833 12,953 - number containing faecal coliforms 15 12 15 - % containing faecal coliforms 0.1 0.1 0.1 Service reservoirs with faecal coliforms detected 11 11 14 - % of all service reservoirs 4.4 4 6
table 14.3 Northumbrian Water Limited
WATER QUALITY IN SUPPLY ZONESColumns 'CBU' show, for determinations, contraventions covered by undertakings and, for zones, the total number of zones covered by undertakings in 2000. Column 'E' shows the number of zones for which new enforcement action is under consideration as a result of contraventions of the PCV in 2000. Please refer to the Introduction to Part 2 for more detailed explanation of this table. PARAMETER DETERMINATIONS in 2000 ZONES (111 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2000 2000 1999 1998 Coliforms 7,429 32 0.4 0 0 0 0 0 1 Faecal coliforms 7,429 5 <0.1 0 0 0 5 0 6 Colour 7,427 6 <0.1 0 0 0 5 2 4 Turbidity 7,428 4 <0.1 0 0 0 4 4 11 Odour 950 1 0.1 0 0 0 1 2 0 Taste 951 1 0.1 0 0 0 1 1 2 Hydrogen ion 7,428 0 0.0 0 0 0 0 0 0 Nitrate 992 0 0.0 0 0 0 0 0 0 Nitrite 992 0 0.0 0 0 0 0 0 0 Aluminium 3,480 5 0.1 1 1 0 5 2 6 Iron 3,480 66 1.8 61 31 0 35 43 35 Manganese 3,480 14 0.4 8 7 0 10 14 26 Lead 1,704 14 0.8 8 6 0 12 13 20 PAH 464 1 0.2 0 0 0 1 0 2 Trihalomethanes 618 4 0.6 1 0 0 1 3 7 Total pesticides 1,475 0 0.0 0 0 0 0 1 0 2,4-D 1,490 0 0.0 0 0 0 0 1 0 Chlortoluron 1,439 1 <0.1 0 0 0 1 1 1 Diuron 1,439 0 0.0 0 0 0 0 0 1 Isoproturon 1,439 0 0.0 0 0 0 0 22 0 MCPA 1,490 24 1.6 0 0 0 24 22 0 Other Pesticeds 68,884 0 0.0 0 0 0 0 0 0 All others 21,809 0 0.0 0 0 0 0 0 0 TOTAL 153,717 178 0.1 79 - - - - - *111 zones in 1999; 112 zones in 1998.
table 14.4 Northumbrian Water Limited
SUMMARY OF ENFORCEMENT ACTION CONSIDERED IN 2000Regulation Reason for enforcement 3(3)c Contravention of the standard for manganese in three zones, turbidity in one zone and colour in one zone 3(7) Contravention of the total coliforms standard at one treatment works. 3(7) Contravention of the total and faecal coliform standards at one service reservoir and the faecal coliform standard at two service reservoirs. 23(1) Disinfection failure at one treatment works.
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Published 11 July 2001
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