Annex 6

(Art. 6 para. 1 and 7 para. 1)

Discharge of Other Polluted Wastewater into Waters or into Public Sewers

1 General requirements

¹For polluted wastewater other than communal or industrial wastewater, the authorities shall determine the requirements on discharge on the basis of the characteristics of the wastewater, the state of the art and the condition of the body of waters concerned. In so doing they shall take account of international or national standards, directives published by the FOEN or standards worked out by the sector concerned in co-operation with the FOEN.

²Precipitation water running off built-up or sealed surfaces and not mixed with other polluted wastewater is also regarded as other polluted wastewater.

³In order that the state of the art be maintained, polluted wastewater from sectors, processes and plants, must comply at least with the requirements of No 2; numerical requirements apply at the site of discharge.

2 Special requirements

21 Continuous cooling installations

¹Plants with continuous cooling installations must be designed and operated according to the state of the art so that as little heat as possible is generated and the waste heat is recovered as far as possible.

²Dissolved organic carbon in the cooling water (DOC) may be increased by at most 5 mg/l DOC.

³If potential water pollutants are added to the cooling water (e.g. biocides), requirements for discharge of these substances shall be specified.

⁴In addition, for discharge into watercourses and stretches of standing water on rivers, the following apply:

1. the temperature of the cooling water may amount to a maximum of 30 °C; in derogation, the authority may permit the temperature to amount to a maximum of 33 °C if the temperature of the waters from which the withdrawal is made exceeds 20 °C; if the water temperature exceeds 25 °C, the authority may permit exceptions if the increase in the water temperature amounts to a maximum of 0.01 °C per discharge or the discharge comes from an existing nuclear power plant;
2. a watercourse must not warm up by more than 3 °C above or below the temperature in its as near natural as possible state, or, in trout water stretches, by more than 1.5 °C; furthermore, the water temperature must not exceed 25 °C;
3. the spillway construction must guarantee rapid mixing;
4. the waters must be warmed up slowly enough to avoid any harmful effects on communities of plants, animals and micro-organisms.

⁵When discharging into lakes, additional requirements in accordance with paragraphs 1–3 of the discharge conditions shall be determined on a case by case basis according to local conditions, in particular concerning the temperature of the cooling water, the depth and type of discharge.

⁶When discharging into public sewers, in addition to the requirements in accordance with paragraphs 1–3, the temperature of the wastewater discharged may not exceed 60 °C and the temperature in the sewer systems may not exceed 40 °C after mixing.

22 Closed-circuit cooling installations

¹When discharging mud-loaded water from closed-circuit cooling installations into a body of water the following values may not be exceeded:

1. temperature: 30 °C;
2. total suspended solids: 40 mg/l;
3. dissolved organic carbon*(DOC):* 10 mg/l.

²If potential water pollutants are added to the cooling water, requirements for such substances shall be specified.

23 Construction sites

¹Wastewater from construction sites may be discharged into a body of water or public sewers if it complies with the general requirements for industrial wastewater in accordance with Annex 3.2 number 2.

²In addition, the following values may not be exceeded when discharging into a body of water:

1. AOX: 0.08 mg/l X;
2. nitrite: 0.3 mg/l N.

24 Façade and tunnel cleaning

¹Wastewater from façade or tunnel cleaning may be discharged into a body of water only if it contains no detergent and has been sufficiently purified in a plant.

²It may be discharged into public sewers if it does not make the recovery of the sludge difficult and if the treatment efficiency of the plant is sufficient to eliminate potential water pollutants.

25 Landfills

¹Landfill leachate may be discharged into waters if:

1. it complies with the general requirements for industrial wastewater in accordance with Annex 3.2 number 2;
2. the biochemical oxygen demand*(BOD* 5 ) does not exceed 20 mg/l O2; and
3. dissolved organic carbon*(DOC)* does not exceed 10 mg/l C.

²It may be discharged into a public sewer if it complies with the general requirements in accordance with Annex 3.2 number 2.

³The authorities shall determine on a case by case basis whether the values specified in paragraphs 1 and 2 must be adapted and if additional requirements must be issued due to the composition of the leachate or the condition of the of waters in question.

26 Gravel conditioning

¹Water from gravel washing may be discharged into a body of water if:

1. it complies with the general requirements for industrial wastewater in accordance with Annex 3.2 number 2;
2. the pH does not exceed 9.

²It shall not be discharged into a public sewer.

27 Fish farms

¹Only feedstuff low in phosphorus may be used on fish farms.

²Plants must be de-sludged according to directions of the authorities.

³Water discharged from the plant may not contain more than 20 mg/l (guide value) of total suspended solids.

⁴If therapeutic or other potential water pollutants are used, in particular in order to maintain the health of fish, the authorities shall specify the requirements for the protection of the body of water on a case by case basis.

28 Swimming pools

Water from swimming pools may be discharged into a body of water only if it does not contain more than 0.05 mg/l (guide value) of disinfectant (e.g. active chlorine).