Guidelines to Statutory Order on the Licensing of Waste Water Discharges

15. Collection schemes for settling tanks and holding tanks, etc.

15.1 General provisions of the Environmental Protection Act  
15.2  Collection scheme for holding tanks etc.
15.2.1 General facts about holding tanks
15.2.2 Holding tanks etc. covered by contractual membership of the public waste water service partnership
15.3 Collection scheme for settling tanks
15.3.1 General facts about settling tanks
15.3.2 Properties included under a collection scheme for settling tanks
15.3.3 Settling tanks covered by contractual membership of the public waste water service
15.4 Collection scheme for other drainage systems
15.4.1 Collection scheme for grease separators and sand catchers
15.4.2 Emptying of oil and petrol separators
15.5 Emptying frequency
15.5.1 General
15.5.2 Emptying frequency for holding tanks etc.
15.5.3 Emptying frequency for settling tanks
15.5.4 Emptying frequency for other drainage systems
15.6 Administration of collection schemes  
15.7  Right of appeal

Purpose

The reason for introducing mandatory municipal collection schemes is that the treatment performance of drainage systems is closely related to the emptying frequency. A mandatory collection scheme also ensures the safe disposal of sludge/waste water. Furthermore, a municipal collection scheme makes it possible to identify and repair any defects and damage of the tanks.

15.1 General provisions of the Environmental Protection Act

According to section 19(2) of the Environmental Protection Act, the establishment of underground containers for substances that may pollute groundwater, soil and subsoil is subject to licensing.

Pursuant to section 19(5) of the Environmental Protection Act, the Minister may lay down detailed rules for licensing. Part 15 of the Statutory Order contains such rules.

Part 15 of the Statutory Order empowers the local council to establish mandatory collection schemes for settling tanks, holding tanks, etc. The Statutory Order sets out administrative guidelines for the establishment and operation of municipal collection schemes for the following drainage systems:

	Holding tanks
	Settling tanks
	Other drainage systems, grease separators and sand catchers

The delivery of sludge, waste water, etc. to treatment plants is subject to local council licensing pursuant to section 28(3) the Environmental Protection Act.

Certain substances should not be allowed to enter a treatment plant, and chemical sludge from industrial enterprises should be admitted only after an assessment in each case of the nature of the waste water and the suitability of the treatment plant for processing the particular type of waste water.

15.2 Collection scheme for holding tanks etc.

Pursuant to section 44(1) of the Statutory Order, the local council may introduce a collection scheme for the whole or part of the municipality.

Municipal collection schemes are governed by a set of rules and regulations, cf. section 48(2) of the Statutory Order.

15.2.1 General facts about holding tanks

What is a holding tank?

A holding tank is generally a tank for collecting domestic waste water, i.e. a tank in which all or part of the waste water produced in a household is collected.

Before the adoption of the Environmental Protection Act, many holding tanks were designed only for waste water from water closets, while grey waste water was either discharged or disposed of by percolation. The new type of holding tank is typically designed to accommodate all types of domestic waste water from one or more households. With regard to the installation and licensing of holding tanks, see Chap. 14 above.

Traditionally, collection schemes for holding tanks cover ordinary holding tanks, but over the next few years, an increased need is anticipated for collection schemes for wastes from environmental solutions, such as humus/composting toilets, separation toilets, etc.

15.2.2 Holding tanks etc. covered by contractual membership of the public waste water service partnership

In cases where a contract has been concluded between the landowner and the local council on membership of the public waste water service pursuant to the Act on payment rules for waste water installations etc., the emptying of the holding tank is the responsibility of the local council, cf. section 44(2) of the Statutory Order. In this connection, the local council may decide to include the tank under the municipal collection scheme for holding tanks.

The local council is responsible for establishing, operating and maintaining holding tanks covered by a contractual membership of the public waste water service partnership.

Emptying on request

The local authority is responsible for emptying the holding tank as needed or at the landowner’s request. The local council specifies guidelines for emptying procedures in the rules and regulations governing collection schemes, cf. section 44(4) of the Statutory Order.

15.3 Collection scheme for settling tanks

Pursuant to section 45(1) of the Statutory Orders, the local council can decide that a common collection scheme for sludge etc. from settling tanks shall be introduced in all or part of the municipality.

Municipal collection schemes are governed by a set of rules and regulations.

15.3.1 General facts about settling tanks

The term ‘settling tank’ covers septic tanks, Emscher/Imhoff tanks (combined decanters-digesters) and multiple-compartment tanks for simple physical treatment of the waste water. Settling tanks are designed to remove settleable and floatable material from the waste water before it is passed on for further treatment or discharged.

The residue (sludge) is retained in the tank, where a certain degree of decomposition takes place before the tank is emptied.

New factory-made settling tanks for 1-2 households (up to 10 p.e.) are subject to approval ("VA approval") under the approval scheme for water and drainage systems operated by the Ministry of Housing and Urban Affairs. Approval may be granted by three different procedures: 1) A theoretical assessment of the tank to verify that it complies with the requirements of DS 440. 2) A performance test, and 3) Test results from the Swedish counterpart of the Danish VA-approval scheme.

Settling tanks constructed in situ are subject to approval by the local authorities. A detailed description of settling tank design is given DS 440 "Code of Practice for smaller drainage disposal systems for percolation into the ground".

For settling tanks used in connection with the establishment of infiltration plants, biological sand filters and reed-bed plants capable of serving up to 30 p.e., reference is made to Danish EPA’s Environmental Guidelines Nos. 1-3, 1999 concerning the above low-technology solutions.

15.3.2 Properties included under a collection scheme for settling tanks

Pursuant to section 45 (1) of the Statutory Order, the local council can decide whether a collection scheme for settling tanks is to apply to the whole or only part of the municipality. The scheme is mandatory on all owners of properties located in an area covered by a collection scheme.

Operating a collection scheme for only part of a municipality must be motivated by environmental reasons, e.g. protection of particularly sensitive waters. Another argument could be the variations with regard to the amount of effluent from non-sewered areas with different building density, the greatest need for a collection scheme being found in the areas having the highest building density.

Where possible, a mandatory municipal collection scheme must cover all properties within a defined geographical area. This means that enclaves of properties or single properties cannot be either excluded from or included in the scheme. Nor is it possible to differentiate between properties for intermittent or permanent residence.

15.3.3 Settling tanks covered by contractual membership of the public waste water service

In the case of installations for which a contract has been concluded between the landowner and the local council for membership of the public waste water service, pursuant to the Act on payment rules for waste water installations etc., the local council is responsible for emptying the settling tanks, cf. section 45(2) of the Statutory Order. In this connection, the local council may decide that the tank must be included under the municipal collection scheme. The local council’s responsibility is limited to collecting the tank contents, while the landowner must pay the costs of establishing and maintaining the tank.

15.4 Collection scheme for other drainage systems

Pursuant to section 46 of the Statutory Order, the local council may establish mandatory municipal collection schemes for other drainage systems, especially grease separators and sand catchers.

The municipal collection scheme is governed by a set of rules and regulations, cf. section 48(2) of the Statutory Order.

15.4.1 Collection scheme for grease separators and sand catchers

Where should grease separators be installed?

Grease separators are mainly needed in drainage pipes for waste water with a particularly high content of grease, such as:

	Food processing industries
	Commercial kitchens (at restaurants etc.)

The purpose of installing a grease separator is, primarily, to prevent grease clogging up drainage systems and to protect the pumps and other mechanical equipment of the system from wear. Secondly, waste water with a high grease content may cause problems at the treatment plant.

Where should sand catchers be installed?

Sand catchers are installed in drainage systems for surface run-off.

The purpose of establishing sand catchers is twofold: firstly, to prevent the discharge of sand into watercourses and lakes, and, secondly, to prevent the sand causing unnecessary wear to the pumps and other mechanical equipment of the system. However, sand catchers are typically installed in municipal systems, and thus operated by the public waste water service.

In addition, sand catchers may also be needed in outfalls from minor private enterprises, for example, from washing and cleaning facilities.

15.4.2 Emptying of oil and petrol separators

Statutory Order No. 299 of 30 April 1997 on waste management sets out rules for the handling of waste products from oil and petrol separators, including for the emptying of such installations.

15.5 Emptying frequency

15.5.1 General

Under section 47 of the Statutory Order, the local council has general authority to define different emptying frequencies, depending on the size, design and/or load of the individual settling tank, drainage system, etc.

15.5.2 Emptying frequency for holding tanks etc.

Holding tanks must generally be emptied as needed, i.e. when they are full. The municipal rules and regulations for collection schemes specify procedures for the emptying of such tanks.

Under section 44(4) of the Statutory Order, the party responsible for emptying the tank, typically the landowner, must make a request to the local council to have the tank emptied. The local council fixes a time limit for when and how this request is to be made. In the case of holding tanks covered by a contractual membership of the public waste water service partnership, the owner must request emptying of the tank in accordance with rules laid down by the local council, cf. section 44(5) of the Statutory Order.

15.5.3 Emptying frequency for settling tanks

Guidelines for the emptying frequency for settling tanks are provided in the rules and regulations issued by the local council.

The necessary emptying frequency for settling tanks depends primarily on the load provided by the tank relative to its size and design (number of compartments).

The oldest and smallest settling tanks have a volumetric capacity of approx. 1 m³. The capacity of newer tanks is at least about twice as much.

The ability of tanks with two or more compartments to retain pollutants is significantly better than that of single-compartment tanks with the same load and volume.

The optimal emptying frequency is therefore determined on the basis of the above-mentioned factors.

Guidelines for emptying frequency

Table 15.1 provides guidelines for the emptying frequency for settling tanks as a function of their load, volume and design.

Generally, no financial benefit is gained from introducing collection schemes with different emptying frequencies. This is because of the large variations in the conditions existing in different geographical areas as well as within individual areas, and because it would involve more administration and more haulage.

In such cases, a uniform emptying frequency may be fixed for the entire municipality or for geographically delimited areas thereof, based on the tank size and design and on the load conditions that characterise the area (e.g. a holiday cottage area).

Inspection

Before initiating schemes with different emptying frequencies, the authorities must obtain the necessary information about the load conditions etc. of the relevant tanks. It is therefore recommended to empty all the tanks once in the first year and at the same time inspect the tanks.

Loads and emptying frequencies are based on the number of permanent residents. In holiday cottage areas, the figures for emptying frequencies are likely to be half of those indicated for permanent dwellings.

The local council fixes the emptying frequency for the individual settling tanks, cf. section 47 of the Statutory Order.

15.5.4 Emptying frequency for other drainage systems

The emptying frequency for other drainage systems is fixed according to need.

The local council establishes rules and regulations for emptying frequency for such systems.

15.6 Administration of collection schemes

The local council is responsible for the administration of collection schemes. Pursuant to section 48(1) of the Statutory Order, the local authority also operates the scheme, but the local authority may outsource the operation of the scheme at its own option.

All collection schemes are subject to rules and regulations to be laid down by the local authority.

According to the Act on payment rules for waste water installations etc., collection schemes must be self-sustaining, and separate accounts must therefore be drawn up for each type of collection scheme.

Separate regulations must be issued for:

	Holding tanks
	Environmental solutions
	Settling tanks
	Other drainage systems

The introduction of a collection scheme must be announced in the most widely circulated local papers.

15.7 Right of appeal

No right of appeal

Local council decisions concerning collection schemes pursuant to Part 15 of the Statutory Order cannot be brought before other administrative authorities, cf. section 49 of the Statutory Order.