12 NORTH SURREY WATER LIMITED
Introduction
North Surrey Water Limited supplies on average about 139 Ml/d to about 480,000 consumers in parts of Surrey and Middlesex. 85% of the Company’s water supplies come from the River Thames, with the remainder coming from gravel wells, boreholes and bulk supplies of treated water from Thames Water Utilities Limited. The Company has four treatment works, with river water being treated at three of these sites, and distributes water through 2,500 km of pipes and 22 service reservoirs to 14 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 13,318 determinations in 2000. Of these, 99.90% demonstrated compliance with the relevant PCV, but 13 showed a contravention to have occurred.
Coliforms were not detected at three (75%) of the Company's four water treatment works. At all of the Company's 22 service reservoirs, coliforms were absent from at least 95% of samples. Of the Company's 14 water supply zones in 2000, all complied fully with the relevant water quality standards or had breaches of the standards which were either trivial or were fully covered by undertakings.
Microbiological quality of water leaving treatment works
The Company complied with the sampling frequencies required by regulation 17 at all of its treatment works in 2000.
Table 12.1 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. Differences over the last three years in the number of treatment works, and samples from treatment works in which coliforms were detected are not considered significant.
Contraventions of the microbiological quality standards at one works resulted in the consideration of enforcement action, as shown in table 12.4.
Microbiological quality of water in service reservoirs
The Company complied with the sampling frequencies required by regulation 18 at all of its service reservoirs in 2000.
Table 12.2 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 service reservoirs in which total coliforms were detected. All other differences at service reservoirs are not considered significant.
All contraventions of the standards at service reservoirs are considered trivial.
Water quality in water supply zones
The Company failed to comply with the required sampling frequencies for total coliforms, faecal coliforms and residual disinfectant in one zone and for two individual pesticides in another zone. The contraventions are considered unlikely to recur as a result of action taken by the Company.
Table 12.3 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. Differences over the last three years are not considered statistically significant.
All contraventions of the standards in zones are considered trivial or a covered by undertakings.
Inspection
Audit of plumbosolvency treatment and control programmes of work
In November 2000, Consultants WS Atkins, represented by Mr S Ntifo, 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 compliancee with new lead standards. Based on Mr Ntifo’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 needs, with minor exceptions noted in the report, was confirmed; 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 audit trails on five samples chosen at random. Based on Mr Walls report Mr Waite concluded that:
Water quality has been monitored by appropriate techniques. There are a few improvements which could be made to sample handling and the AQC. With one exception, the Public Record has been maintained up to date.
Follow-up of response to recommendations and arrangements for Cryptosporidium sampling
The Inspectorate audited North Surrey Water Limited on two occasions in November 2000. The Inspectorate concluded that:
the Company has taken satisfactory action in respect of the recommendations made during the 1999 inspection;
the Company has generally implemented satisfactory arrangements for Cryptosporidium sampling, but there is scope for further development of procedures;
samples are collected at appropriate intervals. Water quality has been monitored by appropriate techniques. Where analytical problems have occurred, they have been corrected; and
the Public Record has been maintained up to date.
Inspection of distribution system improvement programme progress
In September 2000, Consultants RPS, represented by Dr S Tooms, 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 Dr Tooms’ 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, 11 recommendations were conveyed to the Company for formal response. The Company is taking action or has already taken action on a number of the recommendations.
Improvement programmes
No 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.
The distribution system improvement programme, due for completion in 2007, is on-going. The Inspectorate is in discussions with the Company concerning the volume of work required.
Incidents
No events regarded as constituting incidents in which drinking water quality demonstrably deteriorated came to the attention of the Inspectorate in 2000.
Enforcement action
Table 12.4 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 12.1 North Surrey Water Limited
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2000 1999 1998 Number of water treatment works 4 5 4 Works with no sampling shortfall 4 4 4 COLIFORMS Total number of determinations 1,117 1,098 1,106 - number containing coliforms 3 0 2 - % containing coliforms 0.3 0.0 0.2 Treatment works with coliforms detected 1 0 1 - % of all works 25 0 25 FAECAL COLIFORMS Total number of determinations 1,117 1,098 1,106 - number containing faecal coliforms 1 0 0 - % containing faecal coliforms <0.1 0.0 0.0 Treatment works with faecal coliforms detected 1 0 0 - % of all works 25 0 0
table 12.2 North Surrey Water Limited
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2000 1999 1998 Number of service reservoirs 22 23 23 Service reservoirs with no sampling shortfall 22 22 18 COLIFORMS Total number of determinations 1,106 1,099 1,135 - number containing coliforms 2 7 11 - % containing coliforms 0.2 0.6 1.0 Service reservoirs with coliforms detected 1 6 8 Service reservoirs with coliforms detected in more than 5% of samples 0 0 1 - % of all service reservoirs 0 0 4 FAECAL COLIFORMS Total number of determinations 1,106 1,099 1,135 - number containing faecal coliforms 0 1 0 - % containing faecal coliforms 0.0 0.1 0.0 Service reservoirs with faecal coliforms detected 0 1 0 - % of all service reservoirs 0 4 0
table 12.3 North Surrey 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 (14 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2000 2000 1999 1998 Coliforms 1,293 4 0.3 0 0 0 0 0 0 Faecal coliforms 1,293 0 0.0 0 0 0 0 0 0 Colour 136 0 0.0 0 0 0 0 0 0 Turbidity 298 0 0.0 0 7 0 0 0 0 Odour 138 0 0.0 0 0 0 0 0 0 Taste 138 0 0.0 0 0 0 0 0 0 Hydrogen ion 697 0 0.0 0 0 0 0 0 0 Nitrate 136 0 0.0 0 0 0 0 0 0 Nitrite 136 0 0.0 0 0 0 0 0 0 Aluminium 136 0 0.0 0 0 0 0 0 0 Iron 307 3 1.0 3 7 0 0 1 1 Manganese 135 0 0.0 0 0 0 0 0 0 Lead 57 0 0.0 0 0 0 0 0 0 PAH 57 0 0.0 0 0 0 0 0 0 Trihalomethanes 61 0 0.0 0 0 0 0 0 0 Total pesticides 332 0 0.0 0 0 0 0 0 0 Other pesticides 2,541 0 0.0 0 0 0 0 0 0 All others 991 0 0.0 0 0 0 0 0 0 TOTAL 8,872 7 0.1 3 - - - - - *14 zones in 1999; 14 zones in 1998.
table 12.4 North Surrey Water Limited
SUMMARY OF ENFORCEMENT ACTION CONSIDERED IN 2000Regulation Reason for enforcement 3(7) Contravention of the total coliform standard at one works
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Published 11 July 2001
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