Report No FR0483

MEASURES TO CONTROL METAL INPUTS TO
SEWERS FROM DIFFUSE SOURCES

FR0483

APRIL 1994

SUMMARY

I BENEFITS

An understanding of the strategies adopted in other European Community (EC) Member States to reduce the input of metals to sewer from diffuse sources.

II OBJECTIVES

To review the current position of Denmark, Germany and The Netherlands with respect to diffuse inputs of metals to sewer.

III REASONS

There is mounting concern throughout the European Community that controls on the input of metals to sewer from point sources will be insufficient to protect sludge disposal routes. It has been recognised that the proportion of the total metal load discharged to sewer from diffuse sources is increasing and that it may be necessary to introduce measures to reduce the contribution from this source.

IV CONCLUSIONS

Even in those EC Member States that have assigned a high priority to environmental protection, few measures have been adopted to reduce the contribution of diffuse sources to the total metal load discharged to sewer.

The Netherlands are in the process of developing a policy in this area. At present this is focused on reducing the pollutant load discharged by light industry and the service sector (which may be considered as diffuse sources because of the lack of data concerning the quality of the effluent discharged). The authorities in Germany have indicated that the presence of metals in sewage sludge is no longer an issue, mainly because stringent controls on point sources have been sufficient to achieve significant reductions in sludge metal concentrations.

The current concern in Germany relates to organic contaminants in sludge, e.g. PCBs, dioxins and other chlorinated compounds. Denmark has adopted a similar approach to The Netherlands, with the emphasis being placed on controlling effluents from point sources that have traditionally not had limits set on their metal load, The USA have adopted a comprehensive policy to reduce the pollutant load removed by urban runoff to separate surface water sewers. A similar policy is under development for the discharge of runoff to combined foul and surface water sewers and it is likely to be based on that developed for separate systems.

V RESUME OF CONTENTS

This report summarises the main sources of diffuse inputs of metals to sewer before identifying the measures adopted to reduce the contribution these sources make to the total metal load discharged to sewer.

Copies of the report are available from FWR, price 25.00, less 20% to FWR Members.