SIST-TP CEN/TR 12566-2:2005
(Main)Small wastewater treatment systems for up to 50 PT - Part 2: Soil infiltration systems
Small wastewater treatment systems for up to 50 PT - Part 2: Soil infiltration systems
This document specifies the recommended requirements for soil infiltration systems ranging in size from a single house to 50 PT receiving domestic wastewater from septic tanks manufactured according to the requirements given in EN 12566-1 and prEN 12566-4.
This document gives design parameters, construction details, installation and component requirements for soil infiltration systems.
Kleinkläranlagen für bis zu 50 EW - Teil 2: Bodeninfiltrationssysteme
Petites installations de traitement des eaux usées jusqu'a 50 PTE - Partie 2: Systemes d'infiltration dans le sol
Le présent document spécifie les exigences recommandées pour les systemes d'infiltration dans le sol dont la taille varie depuis celle d'une simple maison jusqu'a celle d'installations jusqu'a 50 PTE recevant les eaux usées domestiques de fosses septiques fabriquées selon les exigences indiquées dans l'EN 12566-1 et le prEN 12566-4.
Le présent document fournit des parametres de conception, des détails de construction, des exigences concernant l'installation et les différents éléments des systemes d'infiltration dans le sol.
Male čistilne naprave do 50 PE – 2. del: Sistemi za infiltracijo v zemljo
Ta dokument določa priporočene zahteve za sisteme za infiltracijo v tla v velikosti od ene hiše do 50 PE, ki sprejemajo gospodinjsko odpadno vodo iz greznic, izdelanih v skladu z zahtevami standardov EN 12566-1 in prEN 12566-4.
Ta dokument podaja parametre zasnove, podrobnosti konstrukcije ter zahteve za vgradnjo in sestavne dele za sisteme za infiltracijo v tla.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/TR 12566-2:2005
01-september-2005
0DOHþLVWLOQHQDSUDYHGR3(±GHO 6LVWHPL]DLQILOWUDFLMRY]HPOMR
Small wastewater treatment systems for up to 50 PT - Part 2: Soil infiltration systems
Kleinkläranlagen für bis zu 50 EW - Teil 2: Bodeninfiltrationssysteme
Petites installations de traitement des eaux usées jusqu'a 50 PTE - Partie 2: Systemes
d'infiltration dans le sol
Ta slovenski standard je istoveten z: CEN/TR 12566-2:2005
ICS:
13.060.30 Odpadna voda Sewage water
SIST-TP CEN/TR 12566-2:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TP CEN/TR 12566-2:2005
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SIST-TP CEN/TR 12566-2:2005
TECHNICAL REPORT
CEN/TR 12566-2
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
June 2005
ICS 13.060.30
English version
Small wastewater treatment systems for up to 50 PT - Part 2:
Soil infiltration systems
Petites installations de traitement des eaux usées jusqu'à Kleinkläranlagen für bis zu 50 EW - Teil 2:
50 PTE - Partie 2: Systèmes d'infiltration dans le sol Bodeninfiltrationssysteme
This Technical Report was approved by CEN on 19 December 2004. It has been drawn up by the Technical Committee CEN/TC 165.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 12566-2:2005: E
worldwide for CEN national Members.
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Contents Page
Foreword .3
Introduction.5
1 Scope .6
2 Normative references .6
3 Terms and definitions.6
4 Symbols and abbreviations.8
5 General .8
6 Design parameters.8
7 Components .12
8 General requirements for the installation of septic tanks.14
9 Construction requirements .14
10 Specific construction requirements .15
11 Maintenance .28
Annex A (informative) Preliminary site consideration.29
Annex B (informative) Soil investigations .36
Annex C (informative) Selection of suitable sands.45
Bibliography.49
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Foreword
This document (CEN/TR 12566-2:2005) has been prepared by Technical Committee CEN/TC 165 “Wastewater
engineering”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
CEN shall not be held responsible for identifying any or all such patent rights.
This document is considered as Code of Practice and provides the general requirements for packaged and/or site
assembled treatment plants used for domestic wastewater treatment for a total number of inhabitants and
population equivalents (PT) ≤ 50 PT (see Clause 1).
EN 12566 with the generic title "Small wastewater treatment systems up to 50 PT" consists of the following parts:
Part 1: Prefabricated septic tanks (specifies the requirements and laboratory test method for prefabricated
septic tank units. Requirements and tests for treatment efficiency are not specified),
Part 2: Soil infiltration systems (applies for in-situ constructed soil infiltration systems. No treatment
requirements are specified; Technical Report),
Part 3: Packaged and/or site assembled domestic wastewater treatment plants (specifies the requirements
and laboratory test method used to evaluate packaged wastewater treatment plants, which are required to
treat sewage to a predetermined standard),
Part 4: Septic tanks built in situ from pre-fabricated kits - Execution standard (in preparation),
Part 5: Filtration systems (including sand filters) (in preparation),
Part 6: Test methods for the evaluation of the effectiveness of treatment on users site.
The application of the parts of EN 12566 is shown in the following scheme:
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Key
A Domestic wastewater (influent) 2 Infiltration system (into the ground) (see CEN/TR 12566-2;
in preparation)
B Pre-treated wastewater
3 Wastewater treatment plant (see prEN 12566-3)
C Infiltration into the ground
4 Septic tank built in situ (see prEN 12566-4)
D Outlet of treated wastewater (effluent)
5 Filtration systems (see prEN 12566-5)
1 Prefabricated septic tank (see EN 12566-1)
NOTE National regulations may specify different arrangements between the products described in the standards
series EN 12566.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Report: Austria, Belgium, Cyprus, Czech Republic, Denmark,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
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Introduction
This document gives guidance for soil infiltration systems which can be used together with small waste water
systems according to EN 12566-1, prEN 12566-3 or prEN 12566-4 in places of use where legally provisions for soil
infiltration systems do not exist.
National forewords of this document may give information on provisions for soil infiltration in the place of use (see
Clause 5).
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1 Scope
This document specifies the recommended requirements for soil infiltration systems ranging in size from a single
house to 50 PT receiving domestic wastewater from septic tanks manufactured according to the requirements
given in EN 12566-1 and prEN 12566-4.
This document gives design parameters, construction details, installation and component requirements for soil
infiltration systems.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
EN 1085, Waste water treatment – Vocabulary
EN 12566-1, Small wastewater treatment systems for up to 50 PT — Part 1: Prefabricated septic tanks
prEN 12566-4, Small wastewater systems for up to 50 PT — Part 4: Septic tanks assembled in situ from
prefabricated kits
EN 12056-2, Gravity drainage systems inside buildings - Part 2: Sanitary pipework, layout and calculation
EN ISO 10319, Geotextiles – Wide-width tensile test (ISO 10319:1993)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1085 and the following apply.
3.1
biological layer
biological film which grows on the base of the infiltration system or on top of the filter material when pre-treated
effluent infiltrates the subsoil or the filter material
3.2
connection pipe
non-perforated pipe used to connect the septic tank to the distribution chamber
3.3
disposal area
total area of the site where the pre-treated effluent is discharged into the ground using a soil infiltration system
3.4
distribution chamber
chamber allowing even gravity distribution of pre-treated effluent via the distribution pipes
3.5
distribution layer
layer of the system composed of granular fill material in which pre-treated effluent is discharged through infiltration
pipes
3.6
distribution pipe
non-perforated pipe used to connect the distribution chamber to a single infiltration pipe
3.6
dosing chamber
small tank receiving pre-treated effluent and containing a dosing device e.g. a pump, a hydraulic siphon or a tipping
trough, which automatically discharges the desired quantity
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3.7
end connection
perforated and non-perforated pipes and fittings that connect the lower ends of any parallel infiltration pipes, to
enable airflow between infiltration pipes. The connecting fittings may incorporate ventilation and access provision.
3.8
filter material
granular inert material, usually sand, placed beneath the distribution layer, the purpose of which is to provide a
degree of filtration to the pre-treated effluent
3.9
geotextile
fabric, which is permeable to liquid and air but prevents solid particles from passing through it and is resistant to
decomposition
3.10
granular fill material
inert material in which the infiltration pipes are placed in the distribution layer
3.11
impermeable film
inert membrane, which is impermeable to liquid
3.12
infiltration
percolation of effluent around the point at which it is discharged
3.13
infiltration bed
wide excavation in which a number of infiltration pipes are placed in parallel and surrounded by fill material
3.14
infiltration pipes
perforated pipes through which the pre-treated effluent is discharged to the infiltration trench or bed
3.15
infiltration system
series of infiltration pipes, placed in either single trenches or one large bed, used to discharge effluent in such a
way that it percolates into the disposal area
3.16
infiltration trench
trench in which a single infiltration pipe is placed and surrounded by fill material and separated from other
infiltration trenches by undisturbed soil
3.17
land drains
surface or subsurface channels for the transportation of rain water. They are used to dewater ground and divert the
natural flow of surface and subsurface water away from infiltration area
3.18
long Term Acceptance Rate
LTAR
amount of pre-treated effluent which the system can infiltrate during its lifetime without water logging or clogging
2
(l/m /d)
3.19
mesh
fabric, which is permeable to liquid and air but prevents rough solid particles from passing through it and which is
resistant to decomposition. The hole diameters are approximately 1 mm.
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3.20
permeability coefficient
k
measure of the percolation ability of the soil (m/d)
3.21
prefilter
device that helps to prevent clogging of infiltration system
3.22
pre-treated effluent
wastewater that has undergone at least primary treatment
3.23
subsoil
unconsolidated material beneath the topsoil and above the bedrock
3.24
topsoil
upper layer of soil
3.25
water table
level below which the soil is saturated with water
3.26
water table level
surface of the groundwater when related to the ground level or other point of reference
4 Symbols and abbreviations
k Darcy's permeability coefficient determined from small tube permeable test (m/d)
k Normalised permeability coefficient determined from falling head percolation test (m/d)
N
k Constant permeability coefficient determined from constant head percolation test (m/d)
C
5 General
Infiltration systems provide a measure of treatment when constructed according to this document or to appropriate
national regulations; their effectiveness is usually not measured.
The systems described are intended to illustrate the main principles of construction and are subject to national
variation. Provisions in the place of use shall be taken into account. The regulatory authorities shall be contacted.
6 Design parameters
6.1 General
To ensure that a sustainable solution is achieved each site shall be assessed (see Annex A and Annex B). The
choice of infiltration system will depend upon the site considerations detailed in 6.2. The preferential order of
systems is:
Infiltration trench (see 10.2),
Shallow infiltration bed (see 10.3.1),
Vertical infiltration bed (see 10.3.2),
Infiltration mound (see 10.3.3).
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Pre-treated effluent discharging to unsuitable sub-soils may result in system failure.
6.2 Site considerations
6.2.1 Climatic conditions
When designing, constructing and locating the soil infiltration system, climatic conditions in the area such as
extremes of temperature, rainfall, snow shall be taken into consideration.
6.2.2 Water table
The seasonally highest groundwater table shall be determined in the disposal area, prior to the construction.
Unless specified in national regulations or guidance, a minimum of 1,0 m of unsaturated soil and/or filter material
shall be present above the determined seasonally highest level of the groundwater table.
Where these dimensions cannot be accommodated, alternative arrangements (e.g. raised disposal area) shall be
adopted to achieve these dimensions (see 10.3.3).
6.2.3 Location
6.2.3.1 General
In order to take into consideration all relevant site features when locating the disposal areas a detailed site
investigation shall be carried out. Annex A lists the site considerations which should be assessed as part of the site
investigation; all or some of these considerations may be defined by the national authorities.
In absence of any national regulations or guidance, the disposal area shall be located according to the following
minimum criteria:
No part of the soil disposal area shall be closer than 4 m to the nearest point of the nearest habitable
dwelling.
No part of the disposal area shall be within 4 m of the nearest road boundary or ditch nor within 2 m of the
boundary of the adjoining site. Disposal areas in the vicinity of small water courses shall be at least 10 m
from the highest level. Larger water courses will need special considerations.
The growth of any type of tree or plant which develops an extensive root system is limited to a minimum
distance of 3 m from the infiltration system. This restriction also applies to the cultivation of crops which
would inevitably necessitate the use of machinery, even light machinery, likely to disturb the materials
installed at a shallow depth.
Water supply pipes or underground services other than those required by the infiltration system itself shall
not be located within the disposal area.
Access roads, driveways or paved areas shall not be located within the disposal area.
6.2.3.2 Groundwater protection
Groundwater, in particular any water to be used for drinking shall be protected.
The risk of polluting groundwater is minimised when the disposal area is hydraulically downslope of groundwater
sources.
NOTE The direction of the groundwater flow may be estimated from a trial hole test (see Annex B) and also from the
topography, wells and local knowledge.
Distances are based chiefly on the most important geological and hydrogeological factors, e. g. the type and depth
of subsoil and the depth to the water table, all of which can be assessed as part of the detailed site investigations.
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It is not possible to specify with certainty the minimum safe distance between disposal areas and any system,
which collects drinking water. As a guide for countries where no national regulations or guidance exists a minimum
distance of 30 m may be used. However local conditions may require a far greater distance.
6.3 Dimensioning
The biological layer restricts the infiltration into the subsoil. The layer's properties depend on the permeability of the
soil, the loading rate (hydraulic and organic) and oxygen conditions.
Soil properties such as grain size distribution (soil type), relative compaction, discontinuities and saturation (Table 1
and Annex B) affect the permeability.
Table 1 — Relations between K-values and LTAR
k
Soil type k k LTAR
N C
2
m/d(m/s)
(l/m /d)
m/d m/d
Medium and coarse > 100 > 12 Not applicable Direct infiltration is
gravel not permitted
-3
(> 1 × 10 )
Mixtures of fine gravel 1 to 100 0,8 to 12 1,5 to 12 20 to 50
-5 -3
and coarse sand
(1 × 10 to 1 × 10 )
Fine or silty sand or till 0,5 to 10 0,6 to 2 0,5 to 1,2 15 to 30
-6 -4
(6 10 to 1 10 )
× ×
Silt or sandy silt 0,1 to 1 0,4 to 0,8 0,15 to 0,5 10 to 15
-7 -5
(1 × 10 to 1 × 10 )
Silty clay loam 0,01 to 0,1 0,1 to 0,4 0,15 10
-7 -6
(1 × 10 to 1 × 10 )
Silty clay or clay < 0,001 < 0,1 < 0,15 Direct infiltration
-8
not possible
(< 1 × 10 )
The Figures 1 to 3 show maximum recommended values for LTAR depending on the k coefficient type.
National regulations or guidance may determine which evaluation method should be used and the acceptable
criteria. From the determined LTAR and the anticipated loading, the area of any infiltration system can be
calculated in accordance with equation 1.
Figure 1 — Relation between LTAR and k
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Figure 2 — Relation between LTAR and k
N
Figure 3 — Relation between LTAR and k
C
A = Q LTAR (1)
d
where
A is the infiltration system area (m²);
3
LTAR is the value given either from Table 1 or Figures 1 to 3 or Annex B (B.3.1) (m /m²/d);
3
Q is the total daily flow (m /d).
d
Annex B describes some methods of how the soil parameters could be determined and gives some information
about the determination of LTAR.
6.4 Influent parameters
The infiltration system shall be designed to accept the total daily flow from at least one house.
The infiltration systems are intended to receive only domestic wastewater (without any other water such as
rainwater) pre-treated in a septic tank. Systems to treat commercial wastewater (restaurants, hotels, etc.) require
different design.
In the absence of national regulation or guidance or other reliable data, a minimum value of 150 l per day and per
inhabitant may be used for loading calculation.
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6.5 Selection of infiltration system
Start with LTAR and progress across the Table 2 considering each parameter in turn. See also informative
annexes.
Table 2 — Infiltration system basic selection matrix
Measured Water table Soil Fissured Slope Replace System
LTAR level stability rock native soil type
Good Low Good No — No Infiltration
trench
Good Low Bad No Shallow No Shallow
infiltration
bed
Low Low — Yes Shallow Yes Vertical
or steep infiltration
bed
Very high High or — Yes — Yes Infiltration
or very none mound
low
7 Components
7.1 General
In the absence of any national regulation or guidance the following requirements apply.
7.2 Pipes
7.2.1 General
All pipes shall be manufactured in accordance with the requirements of the relevant EN, if available or, in their
absence, with the specifications valid in the place of use.
7.2.2 Distribution pipe
The following specific requirements shall be complied with:
The nominal diameter of the distribution pipe located between the septic tank and the distribution chamber,
shall at least be equal to the diameter of the outlet of the septic tank.
For the distribution pipes following the distribution chamber, the minimum internal diameter (ID) shall be
80 mm for gravity systems and 32 mm for pressure systems.
7.2.3 Infiltration pipe
7.2.3.1 General
Fields drainpipes shall not be used.
7.2.3.2 Infiltration pipe diameter
The minimum internal diameter of the infiltration pipes shall be 80 mm for gravity systems and 32 mm for pressure
systems
7.2.3.3 Infiltration pipe perforation
The infiltration pipes shall have holes or slots and a smooth internal inner surface.
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The perforations shall be dimensioned and spaced to ensure that granular fill cannot enter the infiltration pipe and
that effluent can flow easily through the perforation without clogging.
7.3 Granular fill material
Granular fill materials used in Europe vary greatly, however it is usually sand in the range of 2 mm to 8 mm or
gravel in the range of 8 mm to 32 mm.
Granular fill shall be inert, washed and graded.
7.4 Geotextile and mesh
Infiltration pipes shall be covered, with a suitable geotextile T (Table 3) to prevent contamination of the granular fill
material e.g. by fine particles of soil. In fissured rock, to avoid sand from being washed out into the ground, a more
porous geotextile B (Table 3) or mesh X shall be used.
Geotextile shall be in accordance with EN ISO 10319.
Table 3 — Geotextile and mesh properties
a
Characteristics Geotextile T Geotextile B Mesh X
Tensile strength
≥ 12 kN/m ≥ 6 kN/m ≥ 6 kN/m
-1 -1 -1
Permittivity
≥ 0,05 s ≥ 0,03 s ≥ 0,03 s
Filtration porosity > 140 µm > 140 µm
≤ 125 µm
Class 1 1 -
a
geomesh can replace geotextile B
7.5 Impermeable film
Impermeable film may be used on the sides of the infiltration system to prevent lateral flow.
This film shall be at least 200 µm thick HDPE or an alternative material of an equivalent strength, which will not
puncture or tear.
7.6 Effluent pumping systems
Effluent pumping systems may be used to transport effluent to remote infiltration systems, to raise effluent from
deep septic tanks and/or for pressure infiltration systems.
Effluent pumps shall not be installed directly in septic tanks but in a separate pumping chamber, which may be
constructed as part of other structures on site.
Suitable wastewater pumps with a minimum free passage of 10 mm should be used.
7.7 Dosing system
To provide efficient distribution of the effluent over the full length of the infiltration pipes, the use of a dosing system
is highly recommended.
7.8 Chambers
Chambers shall be watertight, smooth on the inside and be fitted with a removable cover to facilitate maintenance
and inspection.
Dosing and distribution chambers may be combined into a single structure.
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To prevent backflow the inlet of the chamber shall be above the highest operating water level within the dosing
chamber.
The outlets from the distribution chamber shall be adjustable to enable even flow to the distribution pipes, and may
also include optional outlets for alternative infiltration areas.
8 General requirements for the installation of septic tanks
8.1 General
Septic tank shall be installed in accordance with national regulations or guidance and manufacturers instructions.
The outlet pipes from the septic tank shall have a fall of at least 0,5 %. Prior to installation, the use of grease
separator shall be considered.
The use of a prefilter shall also be considered.
8.2 Ventilation
Generally, a ventilating stack provides an air outlet. National requirements may specify either a separate ventilation
stack or the buildings ventilating stack. When using building ventilation stack, requirements are given in
EN 12056-2.
An independent ventilation pipe may be required in certain circumstances.
The ventilating stack shall not be fitted with an air admittance valve.
9 Construction requirements
9.1 General
All infiltration systems require a margin of 1 m, which is part of the disposal area. Excavation of trenches or beds
should be carried out very carefully in order to avoid disturbing the surrounding soil.
9.2 Installation on sloping sites
Generally, the infiltration pipes shall be installed parallel to contours of the ground (see Figure A.2).
9.3 Land drains
Land drains shall be installed when it is required to prevent migration of surface water or groundwater into the
infiltration system.
9.4 General precautionary measures for excavation works
Excavation is not recommended when the ground is wet.
Trenches and beds should be covered during rainy weather and back-filled as soon as possible.
The excavation process shall not cause compaction of the ground area which is intended for the infiltration. If
necessary, the sides and base of the excavation shall be raked. Machinery shall not traverse the area after the
work has been completed.
9.5 Installation of chambers
9.5.1 General
Chamber connections shall be watertight and accommodate soil settlement.
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9.5.2 Distribution chamber
The chamber should be placed directly on the granular fill material so that it is level and stable. For a gravity
system a minimum gradient of 0,5 % shall be provided between the septic tank and the distribution chamber.
9.5.3 End connections
When used, the end connections shall be installed level within the granular fill material.
9.6 Inspection of infiltration pipes
Before installation, the holes in the infiltration pipes shall be inspected to check that they are of the correct size and
aperture and free from debris.
9.7 Access and inspection
Access points are required at distribution chambers and dosing chambers. Access or inspection points are
recommended at the ends of infiltration pipes. The covers shall be visible and installed to prevent the entry of
water.
The access and inspection points can also provide an indication of the extent of the infiltration systems.
All covers shall be accessible for maintenance and inspection of the system.
9.8 Backfilling
Soil, free from large objects such as stones or lumps may be used as backfill. This soil shall be laid in successive
layers over the geotextile, taking care that the pipes and chambers are not displaced.
Sand or soil shall be used to backfill over the end connections.
In order to accommodate any subsequent settling of the backfill material, an allowance shall be made when
backfilling.
9.9 Covering
The area over the infiltration system shall not, even partially, be covered by a surface, which is air and water
impermeable.
Climatic conditions can require frost insulation which shall be permeable.
9.10 Health and safety
Relevant national health and safety requirements shall be complied with.
10 Specific construction requirements
10.1 General
In addition to the common requirements of clause 9, the following requirements shall also apply in specific
circumstances.
NOTE It is advisable to construct the infiltration system as close to ground level as possible.
Infiltration pipes shall be laid on the fill material with the perforations facing downwards.
10.2 Infiltration trench
10.2.1 General
Figures 4 and 5 show examples of infiltration trenches.
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10.2.2 Excavation of trenches for the distribution chamber and distribution pipes
Ensure that adequate fall is available to construct a gravity fed system. If this is not possible, a pumped system
shall be used.
Excavation shall allow for a 0,10 m thick sand layer below the distribution chamber and pipes.
The sides and base of the trench shall be free from any large object. The base shall be level.
...
SLOVENSKO SIST-TP CEN/TR 12566-2
TEHNIČNO
september 2005
POROČILO
Male čistilne naprave do 50 PE – 2. del: Sistemi za infiltracijo v zemljo
Small wastewater treatment systems for up to 50 PT –
Part 2: Soil infiltration systems
Petites installations de traitement des eaux usées jusqu'a 50 PTE –
Partie 2: Systemes d'infiltration dans le sol
Kleinkläranlagen für bis zu 50 EW – Teil 2: Bodeninfiltrationssysteme
Referenčna oznaka
ICS 13.060.30 SIST-TP CEN/TR 12566-2:2005 (sl)
Nadaljevanje na straneh II in od 1 do 50
© 2016-05. Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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NACIONALNI UVOD
Tehnično poročilo SIST-TP CEN/TR 12566-2 (sl), Male čistilne naprave do 50 PE – 2. del: Sistemi za
infiltracijo v zemljo, 2005, ima status slovenskega tehničnega poročila in je istoveten evropskemu
tehničnemu poročilu CEN/TR 12566-2 (en, de, fr), Small wastewater treatment systems for up to 50 PT
– Part 2: Soil infiltration systems, 2005.
NACIONALNI PREDGOVOR
Evropsko tehnično poročilo CEN/TR 12566-2:2005 je pripravil tehnični odbor Evropskega komiteja za
standardizacijo CEN/TC 165 Odvajanje in čiščenje odpadne vode. Slovensko tehnično poročilo SIST-
TP CEN/TR 12566-2:2005 je prevod evropskega tehničnega poročila CEN/TR 12566-2:2005. V primeru
spora glede besedila slovenskega prevoda v tem tehničnem poročilu je odločilno izvirno evropsko
tehnično poročilo v enem od treh uradnih jezikov CEN. Slovensko izdajo tehničnega poročila je potrdil
Strokovni svet SIST za splošno področje.
Odločitev za izdajo tega standarda je dne julija 2005 sprejel Strokovni svet SIST za splošno področje.
ZVEZA S STANDARDI
S privzemom tega evropskega standarda veljajo za omejeni namen referenčnih standardov vsi
standardi, navedeni v izvirniku, razen tistih, ki so že sprejeti v nacionalno standardizacijo:
SIST EN 1085 Čiščenje odpadne vode – Slovar
SIST EN 12566-1 Male čistilne naprave do 50 PE – 1. del: Predizdelane greznice
SIST EN 12566-4 Male čistilne naprave do 50 PE – 4. del: Montažne greznice, sestavljene na
mestu vgradnje
SIST EN 12056-2 Težnostni kanalizacijski sistemi v stavbah – 2. del: Sanitarni sistem,
načrtovanje in izračun
SIST EN ISO 10319 Geotekstilije – Natezni preskus na širokih preskušancih (ISO 10319:1993)
OSNOVA ZA IZDAJO STANDARDA
– privzem standardizacijskega dokumenta CEN/TR 12566-2:2005
OPOMBE
– Povsod, kjer se v besedilu dopolnila uporablja izraz "evropsko tehnično poročilo", v SIST-TP
CEN/TR 12566-2:2005 to pomeni "slovensko tehnično poročilo".
– Nacionalni uvod in nacionalni predgovor nista sestavni del tehničnega poročila.
– Ta nacionalni dokument je istoveten CEN/TR 12566-2:2005 in je objavljen z dovoljenjem
CEN/CENELEC
Upravni center
Avenue Marnix 17
B-1000 Bruselj
This national document is identical with CEN/TR 12566-2:2005 and is published with the
permission of
CEN/CENELEC
Management Centre
Avenue Marnix 17
B -1000 Brussels
II
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TEHNIČNO POROČILO CEN/TR 12566-2
TECHNICAL REPORT
RAPPORT TECHNIQUE
TECHNISCHER BERICHT junij 2005
ICS 13.060.30
Slovenska izdaja
Male čistilne naprave do 50 PE – 2. del: Sistemi za infiltracijo v zemljo
Small wastewater treatment Petites installations de traitement Kleinkläranlagen für bis zu 50 EW
systems for up to 50 PT – des eaux usées jusqu'a 50 PTE – - Teil 2: Bodeninfiltrationssysteme
Part 2: Soil infiltration systems Partie 2: Systemes d'infiltration dans
le sol
Ta tehnično poročilo je CEN sprejel 19. decembra 2007. Pripravil ga je tehnični odbor CEN/TC 165.
Člani CEN so nacionalni organi za standarde Avstrije, Belgije, Cipra, Češke republike, Danske, Estonije,
Finske, Francije, Grčije, Irske, Islandije, Italije, Latvije, Litve, Luksemburga, Madžarske, Malte, Nemčije,
Nizozemske, Norveške, Poljske, Portugalske, Slovaške, Slovenije, Španije, Švedske, Švice in
Združenega kraljestva.
CEN
Evropski komite za standardizacijo
European Committee for Standardization
Comité Européen de Normalisation
Europäisches Komitee für Normung
Upravni center: rue de Stassart, 36, B-1050 Brussels
© 2005 CEN. Lastnice avtorskih pravic so vse države članice CEN Ref. oznaka: CEN/TR 12566-2:2005 E
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SIST-TP CEN/TR 12566-2 : 2005
Vsebina Stran
Predgovor . 4
Uvod . 6
1 Področje uporabe . 7
2 Zveze s standardi . 7
3 Izrazi in definicije . 7
4 Simboli in kratice . 9
5 Splošno . 9
6 Parametri projektiranja . 10
6.1 Splošno . 10
6.2 Pogoji mesta uporabe . 10
6.2.1 Podnebne razmere . 10
6.2.2 Vodna gladina . 10
6.2.3 Lokacija . 10
6.3 Dimenzioniranje . 11
6.4 Parametri vtoka . 13
6.5 Izbira sistema za infiltracijo . 13
7 Sestavni deli . 13
7.1 Splošno . 13
7.2 Cevi . 13
7.2.1 Splošno . 13
7.2.2 Razdelilna cev . 13
7.2.3 Infiltracijska cev . 14
7.3 Zrnati polnilni material . 14
7.4 Geotekstilije in mreža . 14
7.5 Neprepustna obloga . 14
7.6 Sistemi za črpanje odpadne vode . 14
7.7 Dozirni sistem . 15
7.8 Komore . 15
8 Splošne zahteve za vgradnjo greznic . 15
8.1 Splošno . 15
8.2 Prezračevanje . 15
9 Zahteve za konstrukcijo . 15
9.1 Splošno . 15
9.2 Namestitev na strmih mestih uporabe . 15
9.3 Drenaže . 16
9.4 Splošni previdnostni ukrepi za izkopavanja . 16
9.5 Namestitev komor . 16
9.5.1 Splošno . 16
9.5.2 Razdelilna komora . 16
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9.5.3 Končni priključki . 16
9.6 Pregled infiltracijskih cevi . 16
9.7 Dostop in pregled . 16
9.8 Zasipavanje . 16
9.9 Prekrivanje . 16
9.10 Zdravje in varnost . 17
10 Posebne zahteve za konstrukcijo . 17
10.1 Splošno . 17
10.2 Infiltracijski jarek . 17
10.2.1 Splošno . 17
10.2.2 Izkop jarkov za razdelilno komoro in razdelilne cevi . 17
10.2.3 Izkop infiltracijskih jarkov . 17
10.3 Infiltracijska ležišča . 21
10.3.1 Plitko infiltracijsko ležišče . 21
10.3.2 Vertikalno infiltracijsko ležišče . 23
10.3.3 Infiltracijski nasip . 25
11 Vzdrževanje . 29
11.1 Splošne zahteve . 29
11.2 Komore in cevovod . 29
Dodatek A (informativni): Predhodna obravnava mesta uporabe . 30
Dodatek B (informativni): Raziskava tal . 37
Dodatek C (informativni): Izbira primernega peska . 46
Literatura . 50
3
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SIST-TP CEN/TR 12566-2 : 2005
Predgovor
Ta dokument (CEN/TR 12566-2:2005) je pripravil tehnični odbor CEN/TC 165 Odvajanje in čiščenje
odpadne vode, katerega sekretariat vodi DIN.
Opozoriti je treba na možnost, da so lahko nekateri elementi tega dokumenta predmet patentnih pravic.
CEN ne prevzema odgovornosti za identifikacijo nekaterih ali vseh takih patentnih pravic.
Ta dokument se uporablja kot kodeks ravnanja in določa splošne zahteve za predizdelane in/ali na mestu
postavitve sestavljene čistilne naprave za čiščenje gospodinjskih odpadnih voda za skupno število
prebivalcev in populacijskih ekvivalentov (PE) 50 PE (glej točko 1).
Skupina standardov EN 12566 s skupnim naslovom "Male čistilne naprave do 50 PE" vključuje naslednje
dele:
– 1. del: Predizdelane greznice (določa zahteve in laboratorijske preskusne metode za enote
predizdelanih greznic. Zahteve in preskusi za učinkovitost čiščenja niso določeni)
– 2. del: Sistemi za infiltracijo v zemljo (uporablja za sisteme za infiltracijo v tla, sestavljene na mestu
vgradnje. Zahteve v zvezi s čiščenjem niso določene; tehnično poročilo)
– 3. del: Predizdelane in/ali na mestu postavitve sestavljene čistilne naprave za gospodinjske odplake
(določa zahteve in laboratorijske preskusne metode za vrednotenje predizdelanih čistilnih naprav
za odpadno vodo, ki morajo prečistiti odpadno vodo v skladu z navedeno kakovostjo)
– 4. del: Montažne greznice, sestavljene na mestu vgradnje – Standard za izvedbo (v pripravi)
– 5. del: Filtrirni sistemi (v pripravi)
– 6. del: Preskusne metode za vrednotenje učinka čiščenja na mestu uporabe
Uporaba delov standarda EN 12566 je prikazana v spodnji shemi:
4
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SIST-TP CEN/TR 12566-2 : 2005
C
1 ali 4
2
A B
C
1 ali 4
5
A B D
3
A D
Legenda:
A gospodinjska odpadna voda (vtok) 1 predizdelana greznica (glej EN 12566-1)
B predčiščena odpadna voda 2 sistem za infiltracijo (v tla)
C infiltracija v tla 3 čistilna naprava za odpadno vodo
(glej EN 12566-3)
D iztok očiščene odpadne vode (odtok)
4 greznica, sestavljena na mestu vgradnje
(glej EN 12566-4)
5 filtrirni sistemi (glej EN 12566-5)
OPOMBA: Nacionalni predpisi lahko določajo drugačne ureditve proizvodov, opisanih v standardih skupine EN 12566.
Skladno z notranjimi predpisi CEN/CENELEC morajo ta evropski standard prevzeti nacionalne
organizacije za standarde naslednjih držav: Avstrije, Belgije, Cipra, Češke republike, Danske, Estonije,
Finske, Francije, Grčije, Irske, Islandije, Italije, Latvije, Litve, Luksemburga, Madžarske, Malte, Nemčije,
Nizozemske, Norveške, Poljske, Portugalske, Slovaške, Slovenije, Španije, Švedske, Švice in
Združenega kraljestva.
5
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Uvod
Ta dokument podaja navodila za sisteme za infiltracijo v tla, ki se lahko uporabljajo z malimi čistilnimi
napravami v skladu z EN 12566-1, prEN 12566-3 ali prEN 12566-4 na mestih uporabe, kjer določbe za
sisteme za infiltracijo v tla zakonsko ne obstajajo.
Nacionalni predgovori tega dokumenta lahko vključujejo informacije o določbah za infiltracijo v tla na
mestu uporabe (glej točko 5).
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1 Področje uporabe
Ta dokument določa priporočene zahteve za sisteme za infiltracijo v tla v velikosti od ene hiše do 50
PE, ki sprejemajo gospodinjsko odpadno vodo iz greznic, izdelanih v skladu z zahtevami standardov
EN 12566-1 in prEN 12566-4.
Ta dokument podaja parametre zasnove, podrobnosti konstrukcije ter zahteve za vgradnjo in sestavne
dele za sisteme za infiltracijo v tla.
2 Zveze s standardi
Za uporabo tega dokumenta so nujni naslednji referenčni dokumenti. Pri datiranih sklicevanjih se
uporablja samo navedena izdaja. Pri nedatiranih sklicevanjih se uporablja zadnja izdaja referenčnega
dokumenta (vključno z morebitnimi dopolnili).
EN 1085 Čiščenje odpadne vode – Slovar
EN 12566-1 Male čistilne naprave do 50 PE – 1. del: Predizdelane greznice
prEN 12566-4 Male čistilne naprave do 50 PE – 4. del: Montažne greznice, sestavljene na mestu
vgradnje
EN 12056-2 Težnostni kanalizacijski sistemi v stavbah – 2. del: Sanitarni sistem, načrtovanje
in izračun
EN ISO 10319 Geotekstilije – Natezni preskus na širokih preskušancih (ISO 10319:1993)
3 Izrazi in definicije
V tem dokumentu se uporabljajo izrazi in definicije, navedeni v EN 1085, ter naslednji:
3.1
biološki sloj
biofilm, ki nastane na dnu sistema za infiltracijo ali po vrhu filtrirnega materiala, ko predčiščena odpadna
voda infiltrira v podtalje ali filtrirni material
3.2
priključna cev
neperforirana cev, ki se uporablja za povezavo greznice z razdelilno komoro
3.3
območje odvajanja
celotno območje mesta uporabe, kjer se predčiščena odpadna voda odvaja v tla prek sistema za
infiltracijo
3.4
razdelilna komora
komora, ki omogoča enakomerno težnostno porazdelitev predčiščene odpadne vode prek razdelilnih
cevi
3.5
razdelilni sloj
sloj sistema iz zrnatega polnilnega materiala, kamor se prek infiltracijskih cevi odvaja predčiščena
odpadna voda
3.6
razdelilna cev
neperforirana cev, ki se uporablja za povezavo razdelilne komore s posamezno infiltracijsko cevjo
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3.7
dozirna komora
majhen rezervoar, ki sprejema predčiščeno odpadno vodo in vsebuje dozirno napravo, npr. črpalko,
hidravlični sifon ali prepustnik, ki samodejno odvede želeno količino
3.8
končni priključki
perforirane in neperforirane cevi ter nastavki, ki povezujejo spodnje konce katerihkoli vzporednih
infiltracijskih cevi in omogočajo pretok zraka med njimi; priključni nastavki lahko vključujejo
prezračevalne in dostopne funkcije
3.9
filtrirni material
zrnati inertni material, navadno pesek, položen pod razdelilnim slojem, da zagotavlja določeno stopnjo
filtracije za predčiščeno odpadno vodo
3.10
geotekstil
material, ki prepušča vodo in zrak, vendar preprečuje prehod trdnih delcev, ter je odporen proti
razkrajanju
3.11
zrnati polnilni material
inertni material, v katerem so infiltracijske cevi položene v razdelilnem sloju
3.11
neprepustna obloga
inertna membrana, ki ne prepušča tekočin
3.12
infiltracija
pronicanje odpadne vode v območju mesta njenega odvajanja
3.13
infiltracijsko ležišče
široka izkopanina, v kateri je vodoravno položenih in s polnilnim materialom obloženih več infiltracijskih
cevi
3.14
infiltracijske cevi
perforirane cevi, po katerih se predčiščena odpadna voda odvaja do infiltracijskega jarka ali ležišča
3.15
sistem za infiltracijo
sklop infiltracijskih cevi, položenih v posameznih jarkih ali enotnem večjem ležišču, ki se uporablja za
odvajanje odpadne vode s pronicanjem v območje odvajanja
3.16
infiltracijski jarek
jarek, v katerem je položena infiltracijska cev, obdana s polnilnim materialom in ločena od drugih
infiltracijskih jarkov z neporušenimi tlemi
3.17
drenaže
površinski ali podpovršinski kanali za odvodnjavanje deževnice, ki se uporabljajo za odvajanje in
preusmerjanje naravnega toka površinske in podpovršinske vode z območja infiltracije
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3.18
stopnja dolgoročnega sprejemanja (LTAR)
količina predčiščene odpadne vode, ki jo sistem lahko infiltrira v svoji življenjski dobi, ne da bi prišlo do
2
zamašitev ali zagozditev (l/m /d)
3.19
mreža
material, ki prepušča vodo in zrak, a preprečuje prehod grobih trdnih delcev, ter je odporen proti
razkrajanju; premeri odprtin so približno 1 mm
3.20
koeficient prepustnosti
k
stopnja zmožnosti pronicanja v tla (m/d)
3.21
predfilter
naprava, ki preprečuje zamašitev sistema za infiltracijo
3.22
predčiščena odpadna voda
odpadna voda, očiščena vsaj s postopkom primarnega čiščenja
3.23
podtalje
nekonsolidiran material pod površinskim slojem tal in nad trdno podlago
3.24
površinski sloj tal
vrhnji sloj tal
3.25
vodna gladina
nivo, pod katerim so tla nasičena z vodo
3.26
nivo vodne gladine
gladina podzemne vode v povezavi z nivojem tal ali drugo referenčno točko
4 Simboli in kratice
k Darcyjev koeficient prepustnosti, določen na podlagi preskusa prepustnosti majhne cevi (m/d)
k koeficient normalizirane prepustnosti, določen na podlagi preskusa pronicanja s spremenljivim
N
hidravličnim padcem (m/d)
k koeficient nespremenljive prepustnosti, določen na podlagi preskusa pronicanja s konstantnim
C
hidravličnim padcem (m/d)
5 Splošno
Če so sistemi za infiltracijo zasnovani v skladu s tem dokumentom ali z ustreznimi nacionalnimi predpisi,
zagotavljajo ustrezno stopnjo čiščenja; njihova učinkovitost navadno ni merjena.
Opisani sistemi so predvideni za prikaz glavnih načel postavitve in se lahko razlikujejo med
posameznimi državami. Upoštevati je treba določbe, veljavne v kraju uporabe. Vzpostaviti je treba stik
z upravnimi organi.
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6 Parametri projektiranja
6.1 Splošno
Za zagotavljanje trajnostne rešitve je treba oceniti posamezno mesto uporabe (glej dodatka A in B).
Izbira sistema za infiltracijo mora temeljiti na pogojih mesta uporabe, ki so podrobno opisani v 6.2.
Prednostni vrstni red sistemov je naslednji:
- infiltracijski jarek (glej 10.2),
- plitko infiltracijsko ležišče (glej 10.3.1),
- vertikalno infiltracijsko ležišče (glej 10.3.2),
- infiltracijski nasip (glej 10.3.3).
Odvajanje predčiščene odpadne vode v neprimerno podtalje lahko privede do odpovedi sistema.
6.2 Pogoji mesta uporabe
6.2.1 Podnebne razmere
Pri projektiranju, postavitvi in lociranju mesta uporabe sistema za infiltracijo v tla je treba upoštevati
podnebne razmere v območju uporabe, na primer skrajne temperature, padavine in sneg.
6.2.2 Vodna gladina
Pred postavitvijo je treba določiti najvišji sezonski nivo gladine podzemne vode v območju odvajanja.
Nad določenim najvišjim sezonskim nivojem gladine podzemne vode mora biti vsaj 1,0 m nenasičenih
tal in/ali filtrirnega materiala, razen če nacionalni predpisi ali smernice ne določajo drugače.
Kjer te dimenzije niso na voljo, je treba uporabiti drugo ureditev (npr. dvignjeno območje odvajanja), da
so te dimenzije zagotovljene (glej 10.3.3).
6.2.3 Lokacija
6.2.3.1 Splošno
Pri določanju lokacije območja odvajanja je treba izvesti podrobno raziskavo mesta uporabe in
upoštevati vse pomembne značilnosti tega mesta. V dodatku A so navedeni pogoji mesta uporabe, ki
jih je treba oceniti kot del njegove raziskave; vse ali nekatere od teh pogojev lahko določajo nacionalni
organi.
Kadar ni ustreznih nacionalnih predpisov ali napotkov, mora biti lokacija območja odvajanja določena v
skladu z naslednjimi najnižjimi merili:
- Noben del območja odvajanja v tla ne sme biti manj kot 4 m oddaljen od najbližje točke najbližjega
bivalnega območja.
- Noben del območja odvajanja ne sme biti manj kot 4 m oddaljen od najbližjega roba cestišča ali
obcestnega jarka in manj kot 2 m od meje sosednjega mesta uporabe. Območja odvajanja v bližini
manjših vodnih tokov morajo biti na razdalji vsaj 10 m od najvišjega nivoja. Pri večjih vodnih tokovih
je treba upoštevati posebne pogoje.
- Rast katerekoli drevesne ali rastlinske vrste z razvejanim koreninskim sistemom je omejena na
razdaljo vsaj 3 m od sistema za infiltracijo. Ta omejitev se uporablja tudi za kultivacijo poljščin, pri
obdelavi katerih se ni mogoče izogniti uporabi strojev ali lahke mehanizacije, ki lahko vpliva na
plitko vgrajene materiale.
- V območju odvajanja ne sme biti vodovodnih cevi ali podzemnih napeljav, razen tistih, ki so
potrebne za sistem za infiltracijo.
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- V območju odvajanja ne sme biti dostopnih cest, dovoznih poti ali asfaltiranih površin.
6.2.3.2 Varstvo podzemne vode
Podzemno vodo, zlasti katerokoli vodo, ki je namenjena za oskrbo s pitno vodo, je treba zavarovati.
Tveganje onesnaženja podzemne vode je manjše, kadar je območje odvajanja hidravlično dolvodno od
virov podzemne vode.
OPOMBA: Smer toka podzemne vode je mogoče oceniti s poskusno jamo (glej dodatek B) ter tudi na podlagi topografije,
izvirov in poznavanja lokalnih razmer.
Razdalje temeljijo v glavnem na najpomembnejših geoloških in hidrogeoloških dejavnikih (npr. vrsta in
globina podtalja ter globina do vodne gladine), ki jih je mogoče oceniti v okviru podrobne raziskave
mesta uporabe.
Najkrajše varnostne razdalje med območji odvajanja in katerimkoli sistemom za odvzemanje pitne vode
ni mogoče določiti z gotovostjo. Kot vodilo za države brez ustreznih nacionalnih predpisov ali napotkov
se lahko uporabi najkrajša razdalja 30 m. Vendar lokalne razmere lahko zahtevajo bistveno večjo
razdaljo.
6.3 Dimenzioniranje
Biološki sloj preprečuje infiltracijo v podtalje. Lastnosti sloja so odvisne od prepustnosti tal, obremenitve
pri odvajanju (hidravlične in organske) ter količine prisotnega kisika.
Na prepustnost vplivajo lastnosti tal, kot so zrnavost (vrsta tal), relativna utrjenost, nehomogenost in
nasičenost (preglednica 1 in dodatek B).
Preglednica 1: Razmerja med vrednostmi K in stopnjo dolgoročnega sprejemanja
Vrsta tal k k k LTAR
N C
2
m/d (m/s) m/d m/d (l/m /d)
Srednji in grob gramoz > 100 > 12 Se ne Neposredna infiltracija
–3 uporablja ni dovoljena
(> 1 x 10 )
Mešanice drobnega 1 do 100 0,8 do 12 1,5 do 12 20 do 50
gramoza in grobega –5 –3
(1 x 10 do 1 x 10 )
peska
Drobni ali muljasti pesek 0,5 do 10 0,6 do 2 0,5 do 1,2 15 do 30
ali zmes ilovice in peska –6 –4
(6 x 10 do 1 x 10 )
Mulj ali peščeni mulj 0,1 do 1 0,4 do 0,8 0,15 do 0,5 10 do 15
–7 –5
(1 x 10 do 1 x 10 )
Muljasta glinasta ilovica 0,01 do 0,1 0,1 do 0,4 0,15 10
–7 –6
(1 x 10 do 1 x 10 )
Muljasta glina ali glina < 0,001 < 0,1 < 0,15 Neposredna infiltracija
–8 ni mogoča
(< 1 x 10 )
Slike 1 do 3 prikazujejo največje priporočene vrednosti za stopnjo dolgoročnega sprejemanja v
odvisnosti od vrste koeficienta k.
Nacionalni predpisi ali napotki lahko določajo metodo za vrednotenje in sprejemljiva merila. Na podlagi
določene stopnje dolgoročnega sprejemanja in pričakovane obremenitve je mogoče izračunati območje
kateregakoli sistema za infiltracijo v skladu z enačbo 1.
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SIST-TP CEN/TR 12566-2 : 2005
Slika 1: Razmerje med stopnjo dolgoročnega sprejemanja in koeficientom k
Slika 2: Razmerje med stopnjo dolgoročnega sprejemanja in koeficientom kN
Slika 3: Razmerje med stopnjo dolgoročnega sprejemanja in koeficientom k
C
kjer so:
2
A območje sistema za infiltracijo (m )
3 2
LTAR vrednost iz preglednice 1 ali s slik 1 do 3 ali iz dodatka B (B.3.1) (m /m /d)
3
Q celotni dnevni pretok (m /d)
d
12
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SIST-TP CEN/TR 12566-2 : 2005
V dodatku B so opisane nekatere metode določanja parametrov tal in podane nekatere informacije o
določitvi stopnje dolgoročnega sprejemanja.
6.4 Parametri vtoka
Sistem za infiltracijo mora biti projektiran za sprejemanje celotnega dnevnega pretoka iz vsaj ene hiše.
Sistemi za infiltracijo so predvideni za sprejemanje
...
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