12.Discharge of waste water into the ground (percolation), Danish Environmental Protection Agency

[Front page] [Contents] [Previous] [Next]

Guidelines to Statutory Order on the Licensing of Waste Water Discharges

12.Discharge of waste water into the ground (percolation)

The provisions of Part 12 of the Statutory Order aim to ensure that the discharge of waste water into the ground, typically by percolation, takes place in an environmentally sound manner. This implies, among other things, that the process of discharge must not involve any pollution risk to surface water or ground water, nor may it cause any sanitary risks.

12.1 General provisions of the Environmental Protection Act

Section 19 of the Environmental Protection Act prescribes rules for the licensing of waste water disposal by percolation into the ground, and section 20 of the said Act establishes procedures for varying or revoking existing percolation licences.

Pursuant to section 19(4) of the Environmental Protection Act, percolation licences are granted by the regional council, unless other rules have been fixed by the Minister. Such rules are laid down in section 28, section 29 and section 31 of the Statutory Order, according to which the licensing competence is, in certain circumstances, transferred to the local council.

The activities that are subject to licensing are described in Chap. 1 of these Guidelines.

12.2 Application procedure

Pursuant to section 32 of the Statutory Order, all applications for a percolation licence must be submitted to the local council. The local council decides whether it has competence to issue a licence in any given case. If not, the local council must refer the matter to the regional council accompanied by the local council’s comments. The local council should provide information on local conditions, including pending municipal and local plans, waste water plans, etc. that are considered important to the relevant application.

The local council must ensure that the conditions described in the application are in compliance with the waste water plan. In this connection, the council must make sure that no other means for waste water disposal, typically sewers, have been or are to be established in the catchment area to which the application refers. If so, the local council may refuse the application.

If there is any doubt as to which of the two councils has authority to deal with the matter, the regional council decides which is the competent authority.

12.3 Local council licensing of percolation of domestic waste water etc.

12.3.1 General

Under section 28(1) of the Statutory Order, the local council has competence to license the establishment of infiltration plants for waste water with a max. load of 30 p.e. This typically corresponds to the discharge from ten households, regardless of the physical location of the property.

The following conditions must be clarified before the local council can issue a percolation licence under section 28 of the Statutory Order:

	Volume and character of waste water
	Considerations to be paid to exclusion zones for water abstraction plants pursuant to section 22 of the Environmental Protection Act
	Clearance distance from the infiltration plant to water abstraction plants
	Clearance distance from watercourses, lakes or the sea
	Suitability of the soil for percolation
	Design of the infiltration plant
	Clearance distance from the highest ground water table
	Indicative clearance distance requirements (clearance distance from other infiltration plants, buildings, site boundaries, etc.)

When planning intensive percolation in relatively large areas, the local authorities should generally take the quality of the area’s ground water resources into account, including their water supply potential. Thus, it would be inappropriate to establish intensive percolation of domestic waste water, for example, in a large holiday-house development located in an area where unprotected ground water is used as a source of drinking water.

12.3.2 Volume and character of waste water

Type of domestic waste water

According to section 28(1) of the Statutory Order, the local council is the licensing authority for waste water systems having a max. capacity of 30 p.e. and handling waste water that is comparable to domestic waste water. This means that it must not contain substances other than those usually present in domestic waste water, nor have a significantly different composition.

Waste water from milking parlours

Waste water from milking parlours should preferably be disposed of by methods other than percolation, for example by collection and spreading on farmland. However, waste water from milking parlours was previously defined as comparable to domestic waste water and percolation considered an acceptable method of disposal under section 28 of the Statutory Order. Existing infiltration plants for waste water from milking parlours are still legal.

Waste water from milking parlours may vary with regard to characteristics, depending on whether all the rinsing water is to be percolated and on the cleaning agents and disinfectants used. The local council must determine the character of the waste water in each given case.

The licensing competence of the local council also includes domestic waste water from toilet buildings, scout huts, commercial and industrial enterprises, etc., provided that the waste water’s content of pollutants can be expressed in p.e., and that its volume does not exceed the equivalent of 30 p.e.

12.3.3 Exclusion zones for water abstraction plants established pursuant to section 22 of the Environmental Protection Act

According to section 28(2)(i) of the Statutory Order, infiltration plants must respect the exclusion zones established under section 22 of the Environmental Protection Act for certain water abstraction plants. Such exclusion zones are generally established around abstraction plants connected to common water supply plants that are subject to licensing under section 20 of the Water Supply Act.

Definition of ‘common water supply plants’

‘Common water supply plants’ means plants that supply or are designed to supply at least ten properties.

Moreover, exclusion zones are generally established around abstraction plants for certain types of enterprise whose production depends on water of drinking water quality (e.g. food processing or pharmaceutical industries). It is usually prohibited to install infiltration plants inside exclusion zones. Usually, exclusion zones have a radius of 300 metres. However, in special cases larger zones may be required.

With regard to small urban communities, it may be appropriate to treat the supply of fresh water and the disposal of waste water together as one activity. Thus, it might be appropriate, in certain circumstances, to connect a single property that has its own water abstraction plant to the common water supply, in order to allow the establishment of an infiltration plant on the property.

12.3.4 Clearance distance between the infiltration plant and water abstraction plants

In addition to the protection of water abstraction plants afforded by the exclusion zones, section 28(2)(ii) of the Statutory Order establishes a clearance distance requirement, according to which the local council is only empowered to license the establishment of infiltration plants with a clearance distance of at least 300 metres from abstraction plants required to supply water of drinking water quality.

The requirement for drinking water quality must be met by all abstraction plants that supply water for consumption by private households and personnel in trade and industry, as well as for the use of enterprises that produce foods, pharmaceutical drugs or other products, and whose water supply is subject to special health requirements. As a main rule, market gardeners producing edible crops also require drinking-water quality for their watering and washing installations. Reference is made in this connection to Part 2 of Statutory Order No. 515 of 29 August 1998 from the Ministry of the Environment on water quality and supervision of water supply plants.

Field irrigation systems, on the other hand, do not need water of drinking water quality. Nor does cooling water or process water for the use of enterprises manufacturing non-edible products have to be of drinking water quality.

The clearance distance from other water abstraction plants, i.e. plants not subject to the drinking water criterion, must be at least 150 metres, cf. section 28(2)(iii) of the Statutory Order.

These clearance distance requirements apply regardless of whether the infiltration plant receives domestic waste water or other similar waste water.

12.3.5 Less stringent clearance distance requirements

Pursuant to section 28(3) of the Statutory Order, the local council may, in special circumstances, reduce the prescribed clearance distance between the infiltration plant and the nearest water abstraction plant to min. 75 metres.

The following requirements may be relaxed:

	The clearance distance from water abstraction plants not subject to the drinking water criterion
	The clearance distance from water abstraction plants supplying or designed to supply less than 10 properties and subject to the drinking water criterion.

A prescribed clearance distance may be reduced only provided that an assessment of the hydrogeological conditions shows that, in all probability, percolation of waste water will not pose any risk of pollution to water abstraction plants. Before granting a licence for the establishment of an infiltration plant subject to reduced clearance distance requirements, the local council must obtain the regional council’s opinion in the matter.

It may be relevant to consider reducing the prescribed clearance distances, for example, in cases where a hydrogeological examination of the local conditions shows that, in all probability, the ground water does not flow in a direction away from the infiltration plant towards the water abstraction plant. However, it is important to note that establishing a water abstraction plant may change the ground water’s natural direction of flow, and that the abstraction process creates a cone of depression around the plant. Depending on the rate of abstraction and other hydrogeological conditions, the ground water will always flow towards the water abstraction plant until it reaches a certain distance from the plant.

There is also a basis for reducing the prescribed clearance distances if, for example, the water abstraction plant is placed on one side of a watercourse, and the infiltration plant is to be established on the other side. However, it is a condition that the water level of the watercourse reflects the level of the ground water, and that it is not possible for polluted ground water to pass under the watercourse.

12.3.6 Clearance distance from watercourses, lakes or the sea

Section 28(2)(iv) of the Statutory Order establishes a requirement for a clearance distance of at least 25 metres between the infiltration plant and watercourses, lakes or the sea. In cases where the clearance distance between the infiltration plant and watercourses, lakes or the sea is less than 25 metres, applications for percolation licences must be submitted in accordance with the provisions applying to applications for a discharge licence, cf. section 16 of the Statutory Order.

12.3.7 Suitability of the soil for percolation

Pursuant to section 28(5)(i) of the Statutory Order, the local council must make sure that soil analyses have been carried out at the property concerned that demonstrate the suitability of the soil for percolation. Danish EPA’s Environmental Guidelines No. 2 1999: "Infiltration plants up to 30 p.e." provides a description of the soil analyses recommended by the Environmental Protection Agency prior to establishing an infiltration plant on a property.

Percolation in contaminated soil

Establishing infiltration plants at locations where the soil is contaminated may cause leaching of pollutants into the ground water. Before licensing an infiltration plant at such locations, the local council must make individual assessments of the risk of leaching associated with establishing such a system.

12.3.8 Design of infiltration plants

Functional requirements

Pursuant to section 28(5)(ii) of the Statutory Order, infiltration plants must be executed and dimensioned such that, after commissioning, the system will not cause any accumulation of waste water on the surface of the ground, unsanitary surface conditions or any other nuisance.

Settling tank and drainage systems

Before percolation, the waste water must be passed through a settling tank. In the case of new systems, the settling tank and the associated drainage systems must be designed in accordance with current guidelines and codes of practice. Thus, new prefabricated tanks are subject to approval (‘VA-godkendelse’) under the approval scheme for water and drainage systems operated by the Ministry of Housing and Urban Affairs, and new tanks constructed in situ must be approved by the local authority.

Operational requirements

New and existing settling tanks must be operated in accordance with the relevant codes of practice and guidelines in force at any given time.

Seepage drains

In order to maintain a low waste water load in areas where infiltration plants are established, the systems must be designed according to the area-load principle (seepage drains/distribution pipes). Systems of the point-load type (e.g. seepage wells) must not be used.

Buildings for permanent residence must be provided with a seepage drain of at least 30 metres for each household, while it is normally sufficient to install 20 metres of seepage drain per household for holiday cottages.

For a description of the construction and dimensioning of infiltration plants, see Danish EPA’s Environmental Guideline No. 2 1999, "Infiltration plants up to 30 p.e." and DS 440 "Dansk Ingeniørforening’s Code of Practice for smaller drainage disposal systems for percolation into the ground".

12.3.9 Clearance distance from the highest ground water table

Pursuant to section 28(5)(vi) of the Statutory Order, the bottom of the infiltration plant must, where possible, be installed at least 2.5 m above the highest ground water level.

The purpose of this requirement is to ensure optimal conditions for the decomposition of pollutants in the waste water. However, for the system to function properly, the clearance distance from the highest ground water level must be at least 1 metre. This may be achieved either by elevating the system, or lowering the ground water table, see below.

Recommendations for measuring the max. ground water level are given in Danish EPA’s Environmental Guidelines, "Infiltration plants up to 30 p.e.".

12.3.10 Indicative clearance distance requirements

In addition to the requirements listed in section 28(2)-(5) of the Statutory Order, the local council should, wherever possible, enforce the following clearance distance requirements:

Infiltration plants are to be sited at least 50 metres from the nearest infiltration plant for domestic waste water. The object of this requirement is to ensure the best possible distribution of the waste water and avoid swamping (paludification) of the area. Exemption from this requirement may be granted in cases where the local conditions are deemed favourable to percolation. Reducing the prescribed clearance distance may also be appropriate if it improves the siting of the infiltration plant relative to water abstraction plants.

Infiltration plants are to be sited at least 5 metres from buildings and site boundaries.

Reference is made to Danish EPA’s Environmental Guidelines, "Infiltration plants up to 30 p.e."

12.4 Local council licensing of percolation of surface run-off

Pursuant to section 29 of the Statutory Order, the local council may, in certain specified cases, issue licences for percolation of surface run-off.

The following conditions must be clarified before the local council can issue a percolation licence:

	Character and volume of surface run-off
	Clearance distance from water abstraction plants
	Design of the infiltration plant, including that actual percolation is to take place in a separate system
	Clearance distance from watercourses, lakes or the sea
	Other requirements regarding clearance distance

12.4.1 Character and volume of surface run-off

Percolation of ordinary surface run-off

Section 29 of the Statutory Order empowers the local council to issue licences for percolation of surface run-off, including run-off from private roads and parking grounds for max. 20 cars. The authority to license the discharge of surface run-off from public roads, railways and parking ground for more than 20 cars is vested in the regional council.

Storm water from roads drained off through pipes after percolating through grass verges has usually been purified to such a degree that it does not pollute the receiving water body. No licence is required in cases where water from minor roads drains into the verge of the road without entering an infiltration plant or water body.

Percolation of other surface run-off

If the water to be percolated contains substances other than those generally present in surface run-off or has a significantly different composition, the licensing competence is also vested in the regional council pursuant to section 30 of the Statutory Order.

This will typically be the case in connection with surface run-off from an enterprise operating outdoor facilities, such as washing plant, filling and emptying stations, etc. In each given case, the licensing authority must assess the effect of the waste water from the facility on the surface run-off. Thus, the composition of surface run-off from, say, washing plant installed at machine pools, which may be contaminated with machine oil, will typically be considered different from that of ordinary surface run-off. Such cases therefore come within the jurisdiction of the regional council.

12.4.2 Clearance distance from water abstraction plants etc.

Pursuant to section 29(1)(iv) of the Statutory Order, only percolation systems with a min. 25 metre clearance distance from water abstraction plants required to produce water for human consumption can be licensed by a local council. This is a relatively short clearance distance, but the reason is that in cases where the pollution load of the surface run-off is higher than usual, the licensing competence is transferred to the regional council, which must then decide, in each given case, which measures to stipulate in the licence in order to protect the ground water, cf. section 30(2) of the Statutory Order.

12.4.3 Design of the infiltration plant

According to section 29(1) of the Statutory Order, the local council is only competent to license the discharge of surface run-off into an infiltration plant if the system concerned receives neither domestic nor process waste water. This requirement was established in order to ensure the proper functioning of the system, as percolating surface water may cause other types of waste water to filter too quickly through the biologically active upper soil layers.

Furthermore, the infiltration plant must be dimensioned, sited and constructed in a manner that prevents accumulation of waste water on the surface of the ground or any other nuisance. This includes that the soil must be capable of draining off the inflowing water. It should also be mentioned that sometimes applications are submitted for the establishment of an infiltration plant in areas where the soil is polluted. When considering such applications, the local council must assess the facts of each particular case, and ensure that the necessary precautions are taken to prevent any leaching of pollutants into the ground water before granting a licence.

No other specific requirements apply to the design of infiltration plants for surface run-off, but the infiltration plant should be constructed in accordance with Danish standard DS 440: "Minor drainage systems with percolation".

12.4.4 Clearance distance from watercourses, lakes or the sea

Section 29(1)(v) of the Statutory Order establishes a requirement for a clearance distance of at least 25 metres between the infiltration plant and watercourses, lakes or the sea. This means that if this requirement cannot be met, an application for a discharge licence must be submitted in accordance with the provisions set out in section 16 of the Statutory Order.

12.4.5 Other clearance distance requirements

Indicative clearance distance requirements

The local council should, where possible, stipulate a clearance distance of at least 20 metres between individual infiltration plants. This clearance distance requirement has been established in order to avoid swamping (paludification) of percolation areas, and may be departed from, provided that the area is deemed to be free from such risk due to good percolation conditions and a sufficiently low ground water level. The clearance distance from site boundaries and buildings should be at least 5 metres.

12.5 Regional council licensing of percolation

12.5.1 General

Under section 31(1) of the Statutory Order, the regional council is competent to issue licences to establish infiltration plants in cases where this competence is not vested in the local council under section 29 and section 30 of the Statutory Order. The scope of its competence includes waste water of a character significantly different from ordinary domestic waste water and waste water volumes exceeding the equivalent of 30 p.e.

Pursuant to section 31(2) of the Statutory Order, percolation licences issued by the regional council must stipulate conditions with regard to the following:

	Volume and character of the waste water
	Compatibility with municipal and regional planning for the area
	Protection of water abstraction plants
	Protection of ground water resources
	Consideration for the water quality of watercourses, lakes and the sea

Disposal of other types of waste water in the subsoil

The regional council is empowered to issue licences for the disposal of other types of waste water in the subsoil, cf. section 19 of the Environmental Protection Act. This includes, for example, the disposal/discharge of process water from the recovery of raw materials into a water-filled gravel pit.

12.5.2 Volume and character of waste water

Pursuant to section 30(1) of the Statutory Order the regional council is empowered to issue licences to establish percolation for all installations having a capacity of more than 30 p.e. and systems for the percolation of surface run-off from public roads and parking grounds for more than 20 cars.

The licensing authority must pay special attention to the risk of polluting ground water and water abstraction plants associated with the percolation of large volumes of waste water.

The regional council has also competence to issue percolation licences for waste water of a character different from that of ordinary domestic waste water.

This typically involves the following types of waste water:

	Process waste water from enterprises, including farms, workshops and machine pools
	Water/cleaning water from swimming pools, including hydro- and thermo-therapeutic tubs.

With a few exceptions, the regional council is always the licensing authority in cases involving percolation of process waste water. The type of process waste water considered suitable for percolation is readily decomposable and has a high content of nutrients.

Process waste water that contains a considerable amount of environmentally incompatible substances must be considered unsuitable for percolation due to the risk of polluting the ground water, unless it has been established with absolute certainty that the substances will decompose completely in the soil without involving any risk of pollution to the environment.

Waste water containing toxic (poisonous), bioaccumulative (liable to increase in amount over a period of time) or persistent (slowly decomposable) substances should not be discharged into infiltration plants.

Percolation of water from swimming pools etc.

Water containing chlorine or other disinfectants from swimming pools or hydro- and thermo-therapeutic tubs etc. is regarded indicatively by the Environmental Protection Agency as process waste water. Thus, the regional council is, basically, the licensing authority where such installations are used more intensively than in ordinary households, e.g. in rented holiday homes or in connection with hotel or training course activities. In all other cases, such waste water is classified as ordinary domestic waste water. The reason for this distinction is that the need to discharge waste water from swimming pools for such purposes must be expected to be higher than from pools for ordinary private use.

Percolation of surface run-off from railways

The regional council is the licensing authority for systems for the percolation of surface run-off from railway areas.

12.5.3 Compliance with municipal and regional planning for the area

The percolation licences for domestic waste water, surface run-off or process waste water granted by the regional council must not conflict with the current water supply and waste water management plans for the area, nor with regional and local planning, cf. section 30(2) of the Statutory Order.

12.5.4 Protection of water abstraction plants and ground water resources

Pursuant to section 30(2)(i) of the Statutory Order, the regional council is responsible for ensuring, for example by carrying out hydrogeological surveys of the area, that percolation will not cause pollution of existing water abstraction plants or ground water resources that may be exploited for future water abstraction.

Hydrogeological survey

A hydrogeological survey may include one or more of the following elements:

	Determination of the flow direction of the ground water (if an infiltration plant is established within a short clearance distance from a water abstraction plant, the ground water should not flow towards the abstraction well)
	Soil analysis to establish whether water abstraction plants are protected from percolating waste water (for example, by an impermeable clay layer).

12.5.5 Compliance with quality objectives for watercourses, lakes and the sea

The regional council must further ensure that the infiltration plant does not impede the achievement of the quality objectives for watercourses, lakes and the sea established in the regional plan, cf. section 30(2)(iii) of the Statutory Order.

Clearance distance from watercourses, lakes or the sea

Under section 30(2)(iv) of the Statutory Order, the clearance distance from an infiltration plant to watercourses, lakes or the sea must be at least 25 metres. This means that applications for the licensing of an infiltration plant that is to be placed less than 25 metres from a water body must be considered in accordance with the rules on waste water discharge, rather than with the rules governing percolation, cf. section 16 of the Statutory Order. When issuing discharge licences in such cases, the licensing authority must pay due regard to any nearby water abstraction plants and the water quality of the receiving water body.

12.5.6 Design of systems for the percolation of chlorine-containing waste water

Systems for percolating chlorine-containing waste water from the installations mentioned in section 12.5.2 should be designed in accordance with the following guidelines:

	Waste water containing chlorine must be disposed of through a separate infiltration plant, which must be incorporated with seepage drains in accordance with the guidelines provided in DS 440. At least 10 metres of seepage drain must be used, and the clearance distance from infiltration plants for domestic waste water must be at least 10 metres.
	The settling tank must be designed as a single-compartment tank.
	Requirements laid down in section 28 of the Statutory Order concerning clearance distances from water abstraction plants, watercourses, lakes and the sea, and the prescribed clearance distance of min. 1 metre from the highest ground water table should be met.
	Installations for discharging chlorine-containing water must be operated manually, not automatically, for example via an overfall or the like. Before reaching the seepage drains, the waste water must pass through a balancing tank with a volumetric capacity of min. 1 m³. The tank must be emptied of sludge, as necessary.

The capacity of infiltration plants for chlorine-containing waste water must be sufficient to handle water drained from hydro- and thermo-therapeutic tubs as well as excess water and filter backwash water from small swimming pools.

Certain hydro- and thermo-therapeutic tubs serve as ordinary bathtubs without chlorination. Waste water from such tubs may be discharged for percolation together with ordinary domestic waste water. However, it is important to note that if the tub is significantly larger than a normal bathtub (approx. 250 litres), emptying the contents into an ordinary settling tank may stir up the sludge at the bottom of the tank. In such cases, it may be necessary to consider installing a larger settling tank.

Infiltration plants cannot be designed with sufficient capacity to receive the emptied contents of swimming pools. The amount of water is much too large. It may be considered to empty swimming pools by spraying the water onto the surface of the ground, see Chap. 13 below. If this is done at a time when the pool has not been chlorinated for at least a month, the danger of scorching should be minimal.

12.6 Transfer of licensing competence from the regional council to the local council

12.6.1 General

In cases where the local council is not the licensing authority pursuant to section 28, the regional council is empowered under section 31(1) of the Statutory Order to transfer to the local council the competence to license the establishment, within a specified area, of infiltration plants for the discharge of waste water from waste water systems representing a load of up to 30 p.e.

However, before ceding licensing powers to the local council, the regional council must ensure that the provisions of section 30(2) of the Statutory Order are observed, viz. that:

	Percolation of waste water does not involve a risk of polluting water abstraction plants and ground water resources
	Establishing an infiltration plant does not impede the achievement of the quality objectives set for the watercourses in the area
	The clearance distance from watercourses, lakes and the sea must be at least 25 metres.

It is a further condition for transferring the licensing competence to the local council that the waste water does not contain substances other than those generally present in domestic waste water or has a significantly different composition.

Before transferring the competence, the regional council must also prescribe rules, cf. section 31(2) and (3) of the Statutory Order, for the local council’s use of the competence transferred to it in the form of general requirements with respect to:

	Clearance distance from water abstraction plants
	Design of the infiltration plant
	Clearance distance from watercourses, lakes or the sea
	Clearance distance from the ground water

12.6.2 Clearance distance from water abstraction plants

The regional council must prescribe rules for the clearance distance from water abstraction plants based on the requirement that, where possible, the clearance distances prescribed in section 28(2) of the Statutory Order must be observed, unless a hydrogeological survey provides reasons for easing the clearance distance requirements.

12.6.3 Design of the infiltration plant

Rules must be prescribed for the design of the infiltration plant, including clearance distances between individual infiltration plants. With regard to design, reference is made to section 12.3.8 above and Danish EPA’s "Environmental Guidelines on infiltration plants up to 30 p.e."

12.6.4 Clearance distance from watercourses, lakes and the sea

In addition, the regional council must prescribe rules concerning the clearance distance from the infiltration plant to lakes, watercourses, ditches, drain pipes and coast lines.

12.6.5 Clearance distance from the ground water etc.

Finally, the regional council must prescribe rules for the clearance distance from the infiltration plant to the ground water or other measures to ensure the proper functioning of the infiltration plant. Regarding the clearance distance from the ground water, reference is made to section 12.3 above. Thus, it is possible to achieve proper functioning of the infiltration plant by combining various measures, such as lowering the ground water table or filling up low-lying areas.

12.7 Percolation in areas where the prescribed clearance distance from the ground water table cannot be observed

Under section 30 of the Statutory Order, the regional council can license an infiltration plant for domestic waste water in areas where the clearance distance from the highest ground water level is less than 1 metre. Pursuant to section 31 of the Statutory Order, the regional council can furthermore empower the local council to license the establishment of such infiltration plants.

Lowering the ground water table

However, in connection with establishing infiltration plants in a limited area, it may sometimes be necessary to lower the ground water level because the infiltration plants may otherwise not be established with sufficient clearance distance from the ground water table.

Any lowering of the ground water table must be effected in compliance with the provisions of the Danish Watercourse Act. This means that the drain pipes installed obtain status as watercourses.

Under the Watercourse Act, the costs associated with lowering a ground water table are therefore allocated among the site owners that are assumed to benefit from the installation.

Infiltration plants to be established within a clearance distance of less than 25 metres from such drain pipes are subject to a discharge licence under section 16 of the Statutory Order. See also Chap. 7 below.

Elevated infiltration plants

In areas where the clearance distance from the ground water table is less than the 1 metre necessary to obtain a licence from the local council, cf. section 28 of the Statutory Order, the infiltration plant may be established as an elevated system. Such systems are constructed on a small mound of sand built on the ground to such a height that both the requirements concerning frost-free protection of the seepage drains and the minimum clearance distance from the highest ground water level are respected.

The competence to issue licences for infiltration plants in areas where the ground water table has been lowered and for elevated infiltration plants is defined in accordance with the principles described above for the general allocation of competence to license infiltration plants for waste water.

12.8 Establishment of infiltration plants

Infiltration plants must be established in accordance with applicable rules and regulations. The percolation of domestic waste water is governed by Danish EPA’s Environmental Guidelines No. 2 1999, "Infiltration plants up to 30 p.e.". Furthermore, DS 440, "Dansk Ingeniørforening’s Code of Practice for smaller drainage disposal systems for percolation into the ground", provides guidelines for the disposal of both domestic waste water and surface water by percolation.

12.9 Amendment or revocation of percolation licences

Under section 20 of the Environmental Protection Act, percolation licences issued in accordance with section 19 of the said Act may be varied or revoked at any time and without compensation being payable on the following grounds:

	Risk of pollution to water supply plants
	Implementation of a different method of waste water discharge in accordance with a waste water plan under section 32 of the Environmental Protection Act
	Environmental protection in general

In such cases, it may also be decided that activities - licensed as well as unlicensed - that were legal at the effective date of the Environmental Protection Act are to be changed or terminated.

Decisions to this effect are made by the licensing authority.

If a sewer system is established in an area as part of the implementation of a different method of waste water discharge in accordance with an approved waste water plan, the authorities are empowered under section 20 of the Environmental Protection Act to order the decommissioning of the infiltration plant without any compensation being payable. In such cases, revocation of the licence is deemed to become effective upon the commissioning of the new system, cf. section 20(4) of the Environmental Protection Act.

Section 20(4) of the Environmental Protection Act applies in cases where a new, full-scale sewer system is established and connected to the public collecting system.

12.10 Administrative procedures for issuing enforcement notices providing for percolation

After the amendment in 1997 of the Environmental Protection Act (Act No. 325 of 14 May 1997 to amend the Environmental Protection Act etc. (waster water treatment in rural areas etc.), section 30 of the Environmental Protection Act provides scope for issuing enforcement notices providing for percolation.

The local council may issue an enforcement notice providing directly for percolation pursuant to section 30(5), if the conditions for disposal of waste water by percolation are met, see section 12.3 above and sections 28, 29 and 31 of the Statutory Order.

Alternatively, the local council may issue an enforcement notice providing for treatment of the waste water concerned to a given level of treatment (in accordance with the four classes of treatment defined in section 11.3 above) and, at the same time, inform the landowner that he may comply with the enforcement notice by establishing an infiltration plant.

For a more detailed description of the procedure for issuing enforcement notices under section 30 of Act, see Danish EPA’s Environmental Guidelines No. 2, "Infiltration plants up to 30 p.e.", cf. section 2.3.

A standard form to be completed by applicants for a licence to establish an infiltration plant is inserted.

12.11 Liability in connection with issuing licences or enforcement notices for the establishment of infiltration plants

The licensing authority should pay special attention to the question of liability in connection with issuing enforcement notices providing for the establishment of infiltration plants. According to section 28 of the Statutory Order, the licensing authority must ensure compliance with a number of conditions and prerequisites, including that the soil must be suitable for percolation. The local council must therefore ensure that the necessary documentation is available, for example, in the form of data obtained from sieve testing of the subsoil, measurement of the ground water level, etc.

The local council should take special care when licensing percolation in areas where the soil is less suitable for this purpose. Danish EPA’s Environmental Guidelines on infiltration plants recommend that the granting of licences for percolation of waste water be refused in such cases, as the risk that the infiltration plant will not function properly is higher. At any rate, the local council should make absolutely sure that it has been documented with sufficient certainty that the soil of the area concerned is suitable for percolation.

12.12 Supervision and enforcement

According to section 53(1) of the Statutory Order, the local council is responsible for supervising private infiltration plants for waste water. The local council is also responsible for supervising infiltration plants for run-off from railway areas in cases where the regional council is the licensing authority.

Under section 53(2) of the Statutory Order, the regional council is responsible for supervising public infiltration plants.

As supervisory authority, the regional council is responsible for ensuring compliance with:

	Conditions stipulated in connection with a licence
	Enforcement notices and prohibition notices

Usually, the licensing authority is also the enforcing authority.

The local council must refer cases of non-compliance with decisions made under section 30 of the Statutory Order to the regional council, which will then take enforcement action against the unlawful conduct in accordance with sections 68 - 70 of the Environmental Protection Act.

12.13 Allocation of competence etc. in matters concerning percolation

Table 12.1 below summarises the requirements to be met by applicants for percolation licences depending on the licensing authority, and table 12.2 is a survey of licensing and supervisory authorities.

Table 12.1
Requirements regarding infiltration plants set out in sections 28, 30 and 31 of the Statutory Order

Licensing for percolation is subject to the following requirements:	s. 28	ss. 30-31
1. Exclusion zones, s. 22 of the Environmental Protection Act	Yes	No *)
2. 300 m from water abstraction plants, drinking water quality. For small systems, the clearance distance may be reduced to 75 metres.	Yes	No *)
3. 150 m from water abstraction plants, not drinking water quality, the clearance distance may be reduced to 75 metres.	Yes	No *)
4. Min. 25 m clearance distance from watercourses, lakes or the sea	Yes	Yes
5. Settling tank	Yes	No
6. Seepage drains	Yes	No
7. Min. clearance distance from ground water 1 m	Yes	No

*) Requirements may only be eased in cases where the regional council estimates that this poses no pollution risk to ground water resources.

Table 12.2
Survey of licensing/supervisory authorities and right of appeal in matters concerning percolation of waste water

Owner/ producer	Size	License	Authority	Super- vision	Authority	Appeal	Authority
private	£ 30p.e.	LC	SO s.28	LC	EPA s.65	no	SO s.33
private	>30 p.e.	RC	SO s.30	LC	EPA s.65	yes	EPA s.91
LC	£ 30 p.e.	LC	SO s.28	RC	EPA s.66(4)	no	SO s.33
LC	>30 p.e.	RC	SO s.30	RC	EPA s.66(4)	yes	EPA s.91

LC: Local council
RC: Regional council
EPA: Environmental Protection Act
SO: Waste Water Management Order
Central government and regional authority licences are included under private owners/producers

12.14 Right of appeal

Decisions made under section 28 of the Statutory Order regarding infiltration plants for domestic waste water with a capacity of 30 p.e. or less cannot be brought before other administrative authorities, cf. section 33 of the Statutory Order.

Nor can decisions regarding percolation of surface run-off under section 29 of the Statutory Order in cases where the local council is the licensing authority be brought before other administrative authorities under section 33 of the Statutory Order.

Regional council decisions pursuant to sections 30 and 31 of the Statutory Order may be referred to the Environmental Protection Agency.

However, the following decisions, cf. section 33(2) of the Statutory Order, cannot be brought before other administrative authorities:

	The granting or refusal of applications for the establishment of an infiltration plant having a capacity of up to 30 p.e. for waste water not containing substances other than those usually present in domestic waste water
	The granting or refusal of applications for a licence to percolate surface run-off, except run-off from public roads or paved areas used for the parking of more than 20 cars
	The transfer of competence to the local council in accordance with section 31(1) of the Statutory Order, cf. section 31(5).

Licences issued by the local council on the basis of a licence issued by the regional council under section 31of the Statutory Order cannot be brought before other administrative authorities.

Finally, Environmental Protection Agency decisions concerning appeals filed against licences issued by a regional council under section 31 and section 32 of the Statutory Order may be brought before the Environmental Appeals Board, cf. section 103 of the Environmental Protection Act.

[Front page] [Contents] [Previous] [Next] [Top]