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Summary and conclusions

In 2007 the municipalities will take over responsibility in cases where waterworks apply for extended water treatment for e.g. pesticides, arsenic or aggressive carbon dioxide. In the project “Compiled experience in issuing permits for extended water treatment” the municipalities will gain an overview of previous cases. Which hazardous substances and treatment methods have been applied for? What reasons and local considerations have been taken into account in the county’s decision? The cases have been assessed differently from county to county. Experience from previous practice is therefore not sufficient to provide the new municipalities with a uniform basis for case administration on extended water treatment.

The municipality becomes the new authority

The counties’ former role as the authority for cases where waterworks apply for permission to use extended water treatment will be transferred to the municipalities by 2007. Extended water treatment could be e.g. treatment of drinking water for pesticides by activated carbon filtration, removal of arsenic or neutralisation of the water to prevent corrosion of water pipes. So far only few permits have been issued for extended water treatment, partly because the Danish strategy is still to use catchments of uncontaminated groundwater for production of drinking water. Most likely the future will bring more cases where water must be treated for a transitional period, while remedial measures are taken to improve groundwater quality.

To ensure as harmonious a basis for administration as possible after 1 January 2007, it is necessary to compile previous experience from the counties in terms of case considerations for extended water treatment.

The purpose of this project is to compile the counties’ experience with cases for extended water treatment at common waterworks, and to investigate previous practice in the area. The project creates an overview of decisions, giving the new municipalities a starting point in their administrative work which can also serve as inspiration when seeking further information.

Extended water treatment cases are collected by the counties

The project has elaborated a series of preconditions that have formed the basis of counties’ selection of cases on extended water treatment. All counties, including municipalities with county status, have then been contacted and asked to send copies of cases where waterworks have applied for extended water treatment permits. These cases have then been divided into groups, according to whether the application was successful or not, and whether the case was appealed to the Danish EPA. In addition, data has been processed according to hazardous substance, treatment method, permit period, reasons for authority decisions, conditions of approval and works in operation in 2006.

Applications for extended water treatment

In Denmark, drinking water is treated by aeration of groundwater and filtration of various natural substances in sand filters. This is known as normal water treatment. If there is a need for further treatment or more complicated processes in order to comply with quality standards, the authorities must issue a special permit for extended water treatment.

Information has been given on a total of 62 cases involving extended water treatment. The cases are divided between 50 permits, eight rejections and four cases where the county has not yet made a decision. All counties and municipalities with county status have participated in the project. The County of West Zealand and the Municipality of Copenhagen have not processed any cases on extended water treatment. Other counties have received from one to 11 cases. Table 1 shows how applications are distributed among various hazardous substances, and which counties have considered the various applications.

Table 1 Overview of no. of applications and their distribution between hazardous substances

The applications are distributed geographically across the country but there is a correlation between hazardous substances in the applications and the geographical variation in groundwater quality in Denmark. Extended water treatment consists of a wide variation in methods, depending on which hazardous substances need to be treated. For a large number of cases, chemicals are added to the water or the water is filtered through other types of filters than sand filters.

Permits for extended water treatment

The counties have issued permits for extended water treatment in 50 cases. Table 2 provides an overview of permits within each hazardous substance.

Table 2 Overview of permits for extended water treatment

Permits for treatment of the groundwater’s main ingredients have been issued for varying periods, from two years to permanent. The extent of the approval period depends on the county. Even though the same treatment methods for the same substances are considered, one county perceives the treatment as a kind of experiment, while another county believes that the method is documented and well known and therefore issues permanent permits. The same applies to arsenic which also shows large variation in the length of approval periods.

Permits for treatment of organic micro contamination have all been issued for temporary periods from six months to six years. Permits are only issued if limit values in drinking water have been exceeded and no water of better quality can be found. In several cases the approval periods have been extended, although not until the waterworks had sent a new application and the specific case had been considered by the county. For all permits, the counties have required that the waterworks continue to protect the groundwater and strive to improve drinking water quality. The permits furthermore include a requirement for frequent water quality monitoring, both in the groundwater and after treatment.

Some treatment methods involve addition of chemicals to the water in order to improve the treatment process. A large proportion of permits, but not all, make demands for purity of the additive to prevent unwanted substances in the water.

Rejection of extended water treatment applications

Authorities have rejected eight applications for extended water treatment. Five of the rejections were in response to xenobiotics, and three rejections were in response to treatment of natural substances. Most important reasons for rejections were:

• Other possibilities exist for procuring clean drinking water to consumers.
• Quality requirements for drinking water have not been violated and the water can therefore be consumed without risk to health.
• Not all possibilities of finding clean groundwater have been investigated.

Appeals to the Danish EPA

In six instances the county decision has been appealed to the Danish EPA because the medical officer or the waterworks has not agreed with the decision. In two appeal cases the Danish EPA sided with the complainant and sent the case back to the county for reconsideration. The argument was that the county had not considered the specific case but rejected the application on the basis of general guidelines from e.g. the Regional Plan. As regards the other appeals, the Danish EPA sided with the county.

Plants in operation in 2006

A number of the permits given by counties for extended water treatment have expired, and the plants are no longer in operation. In addition, a few of the permits have never been applied because the waterworks found other ways of solving their problems. In 2006 there were 29 plants with extended water treatment in operation. These were both large and small plants, treating between 35,000 m³ and 2.5 mill. m³ annually.

Half (14 plants) are treating for natural substances that belong to the main groundwater ingredients. Nine of the plants treat for trace metals such as arsenic and nickel, while five plants treat for xenobiotics such as pesticides and chlorinated solvents. One plant compensates for temporary operational problems at the waterworks.

The decisions are characterised by an individual consideration of each case.

A total of 62 cases for extended water treatment have been collected from all counties in Denmark. The cases are generally very different, and cases involving the same hazardous substances are not assessed equally from county to county. Experience from previous practice can therefore only to a limited extent ensure that future consideration of cases involving extended water treatment is equal amongst the new municipalities.

However, the investigation provides an overview of the extent of cases in this field - which substances are in focus, their treatment methods, and to some extent the basis for decisions and local considerations to be taken into account in each specific case.

Experience from the counties’ case consideration can be summarised as follows:

• Each case must be assessed individually, and the counties must not solely decide on the basis of e.g. guidelines in Regional Plans.
• Decisions are to a high extent characterised by individual conditions for the individual waterworks and in the individual county.
• In cases involving extended water treatment for calcium and hardness, permits are issued solely to improve the economics of waterworks operation, and not because limit values are exceeded.
• For all other substances permits are only issued for extended treatment if limit values for drinking water are exceeded.
• Permit periods vary from two years to 30 years for the same substance and same water treatment method.
• Only temporary permits have been issued for treatment of xenobiotics such as pesticides and chlorinated solvents. Permits have only been given where waterworks have investigated and documented that no water of higher quality can be extracted. The counties have required that waterworks continue to protect groundwater and strive to improve drinking water quality.
• Permits for treatment of inorganic trace elements have been issued for periods between two months to 24 years and include nickel and arsenic. Applications for arsenic removal are all conditioned by the fact that quality requirements for drinking water cannot be followed after the lowering of limit values for arsenic in drinking water in December 2003.
• In general those applications are rejected where consumers may immediately be supplied from other waterworks. In the metropolitan area of Copenhagen, which has a large water consumption, the counties have emphasised that local catchment must be preserved and have issued permits even though consumers may receive water from a regional water supply.

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Version 1.0 Februar 2007, © Miljøstyrelsen.