For sewers in water catchment areas, the interests of environmental protection impose particularly high requirements on the functionality and thus, the planning, execution and rehabilitation and maintenance of these installations. A first step was taken with the ATV-A 142E "Sewers and Drains in Water Catchment Areas" [ATVA142a]. Besides this, some of the States of the Federal Republic of Germany formulated their own regulations or requirement profiles …

In water catchment zone I, the through path of sewers is prohibited in principle.

If, in the public interest, sewers must be laid in water catchment zone I, then the draw off of water is to be suspended. The water supply must be maintained in a suitable manner.

The DVGW - working paper W-101 [DVGWW101] lays down the following with regards to a sewer through path and a lowering or seeping of sewage:

The following are dangerous and generally not permitted in zone II:

• The installations, methods and processes (Abschnitt 6.5.1) permitted in zones III A and III B;
• The passage of sewage;
• Trenches and aboveground waters that are loaded with sewage or substances dangerous to water.

Although the passage of sewage is …

According to [MULUF84] the following requirements apply to single-walled sewers:

• The pipes of materials to DIN 4033 [DIN4033:1979] - even when used in operation as gravity pipes - must be laid to pressure pipe specifications. The pipes must withstand a test pressure of 2.4 bar corresponding to a nominal pressure of 1.6 bar. The same is valid for pipe joints.
• The stability proof must include an enhanced safety factor against collapse of stability of …

According to [ATVA142a], the following facts must be considered beyond the special requirements of stability, and operational safety:

• The piping route is to be selected such that difficult ground and underground conditions are avoided.
• The largest possible distance is to be kept between the sewer and the collection region (water catchment zone I).
• Invasion of the soil must be minimised.
• Leaktightness testing must also be possible after start-up. The …

The laying of pipes and other prefabricated components in water catchment areas are subject to DIN 4033 [DIN4033:1979], ATV-A 139E [ATVA139b] and, since 1997, EN 1610 [DINEN1610:1997].

In addition, the following must be considered according to [ATVA142a] :

• The construction measures must be carried out quickly.
• Vehicles and construction machinery that have fuel and / or oil losses must be removed out of the water catchment area immediately.
• Electrically …

The fulfilment of the "Controllable Protective Measures" mentioned in Abschnitt 6.4.1, which exclude the disadvantageous influencing of the groundwater can be realised, according to [ATVA142a] [MULUF84] by the following methods of processing for sewers:

1. Laying the sewers and pipes in a sealed protective pipe (double-pipe);
2. Laying of single-walled sewers and pipes with additional measures.

In order to avoid misunderstandings, the term "double-walled …

In water catchment zone III, the laying and operation of sewers is generally permissible as long as the necessary measures for protection of the water are carried out. This is equally valid for the construction and operation of structures of the drain and sewer network such as manholes, pumping installations, precipitation overflow and retention ponds [ATVA142a].

With regards to drainage through-pipe and a lowering or seepage of wastewater, the DVGW …

The requirements according to ATV-A 142E [ATVA142a] for planning and execution of sewer work in water catchment zone III hardly deviate from those for sewers outside of water catchment areas. Only the requirements in Abschnitt 6.4.2.2 for the execution must be considered.

In contrast to this, the Federal Ministry for water and waste (StAWA) in Dusseldorf makes detailed requirements [Düsse90] :

• Basically, the number of pipe joints must be reduced to …

According to ATV-A 142E [ATVA142a] an optical inspection in a 5-year cycle is recommended for sewers in the protective zone III and for private sewers (drain systems), the 5-year cycle is mandatory. Corresponding to the condition and the loading of the installation, shorter intervals may be necessary.

The flow is to be stopped immediately if damage to pipes or pipe joints is ascertained during inspection (deviation, retention, back-up). If necessary, …

The above-mentioned requirements regarding the laying and operation of sewers must be transferred in the same sense to their rehabilitation, i.e. for damage of sewers in operation, they must be rehabilitated according to the existing requirements for water catchment areas [ATVA142a] [MULUF84] [Düsse90]. This means that, if necessary, existing systems must be separated or, in other words, the laterals, instead of being taken into the sewer must be …