444 4GERMAN ATV RULES AND STANDARDS W A S T E W A T E R W A S T E ATV-STANDARD ATV-A 105E Selection of the Drainage System December 1997 ISBN 3-934984-01-0 Marketing: Gesellschaft zur Förderung der Abwassertechnik e.V. (GFA) Theodor-Heuß-Allee 17 D-53773 Hennef Postfach 11 65 . 53758 Hennef -Ing.V. in particular data processing machines. Düsseldorf Dipl. in particular those of translation into other languages. (GFA).-Ing.-Ing. Bonn Contents December 1997 Page 2 . Karlsruhe Dipl. Stuttgart Guests: Dipl. Dübendorf/Switzerland Dipl. Pirmasens Dipl.2. Germering Dipl. "Planning of Drainage Systems". Hoffmann. Spellier.-Ing.ATV-A 105E This ATV Standard has been elaborated by the ad hoc Working Group "Drainage Systems" within the ATV Specialist Committee 1. Wien. without the written approval of the publisher. Bonn (as guest) Dr. Hennef All rights.-Ing.-Ing. Krejci. Belting. Brunner. The ad hoc Working group has the following members: Dipl. Gesellschaft zur Förderung der Abwassertechnik e. Lohaus. Hennef 1997 Original German edition produced by: JF•CARTHAUS GmbH & Co.-Ing.-Ing. Austria Dipl. Niedrée. Riedl. are reserved. No part of this Standard may be reproduced in any form by photocopy. Stumwöhrer. Dr. G. München (Chairman) Prof. microfilm or any other process or transferred or translated into a language usable in machines.-Ing. Dippold.-Ing. 4 3.1 2.4 5 6 Area of application Definitions Combined systems Modified combined system Separate system Modified separate system Criteria for the selection of the drainage system Principles Local conditions Technical aspects Cost aspects Planning.1.3 4.1 2. construction and operation Modified drainage systems Separate discharge of precipitation water Decentralised and semi-centralised percolation of precipitation water Central percolation Use of precipitation water Requirements on private property drainage Relevant regulations. literature 4 4 4 5 5 5 5 8 8 8 8 9 11 11 12 12 12 13 13 14 14 December 1997 3 .3 3.2 3.2 2.1 4.ATV-A 105E Notes for users Foreword 1 2 2.5 4 4.1 3 3.2.1 3.2 4. With its application no one avoids responsibility for his own action or for the correct application in specific cases. December 1997 4 . rules of procedure of the ATV and ATV Standard ATV-A 400). It applies for new planning and expansion of drainage systems as well as for the renewal or renovation of existing systems. stormwater or combined water can be dealt with by treatment measures. that the COD loading of the lake or river due to stormwater overflow facilities from combined sewer systems corresponds with that of the inflow of stormwater from separate systems. this applies in particular for the correct handling of the margins described in the Standard. in addition to traditional separate and combined systems. In some Federal German States there are. The revised ATV Standard indicates which aspects are to be taken into account with the selection of the drainage system. This is primarily due to the fact that most sewer systems in Germany have already been established and. Therefore it is not alone the efficiency of the sewage treatment plant but also the conception of the sewerage system with its stormwater overflows and stormwater treatment facilities which is relevant for keeping lakes and rivers clean. legal specifications which are to have priority. In the meantime. The special aspects of rurally structured areas are dealt with in ATV Standard ATV-A 200. technical-scientific/economic collaboration which has been achieved in accordance with the principles applicable for this (statutes. The specification for the elaboration of ATV Standard ATV-A 128 "Standards for the Dimensioning and Design of Stormwater Structures in Combined Sewers" (Edition 4/92) was. With the elaboration of ATV Standard ATV-A 105 (January 1983) one could not yet assume this equivalence. modified systems are gaining in significance. a contract or other legal reason. However. in addition. 1 Area of Application This Standard applies for the planning of drainage systems in which wastewater and precipitation water are disposed of [1]. Foreword With point sources of loading on lakes and rivers it is primarily the discharges of wastewater of the drainage areas. renovating and renewing the existing sewer systems. For this. there exists an actual presumption that it is textually and technically correct and also generally recognised. These aspects were to be taken into account in this current new edition. however. Decisive for an effective water pollution control is which portion of the carried pollutant load from discharged wastewater. not the sole source of information for correct solutions. according to precedents. With the application of ATV-A 128 one can therefore assume a water management equivalence of separate ands combined systems. therefore.. This Standard is an important. mainly in urban areas. The application of this Standard is open to everyone. an obligation for application can arise from legal or administrative regulations.ATV-A 105E Notes for Users This ATV Standard is the result of honorary. the current main task lies in expanding. so that the previous standard gave the water quality management aspects a wide scope. cooling or land drainage water into the stormwater sewer can lead to high costs with a possibly necessary stormwater treatment. is based on the usage. may not be discharged into the combined sewer. parking lots and commercially used hard standing areas an individual examination is necessary which. as a rule. With streets.ATV-A 105E The aim of the Standard is to facilitate achieving an objective decision for the selection of a drainage system by using a series of criteria. the precipitation water can be discharged into natural or artificial bodies of water. runoffs from roof and courtyard surfaces as well as runoffs from residential roads and footpaths. Unpolluted water .1. wells etc. It is incumbent on the diligence of the planner to elaborate an appropriate drainage concept for the protection of lakes and rivers. Due to the limited performance capacity of the sewage treatment plant and in order to limit the sewer crosssection for technical and economic requirements. While the wastewater is fed to the sewage treatment plant and is treated there. above all. 2 Definitions Below are terms used for precipitation water both requiring and not requiring treatment.1 Combined System In the combined system domestic and commercial wastewater and the precipitation water are discharged together in one sewer. 2. The limitation is based on the principle of not discharging any water to a sewage treatment plant whose degree of pollution is less than that required in the effluent of the sewage treatment plant. the soil and the groundwater which is optimised for the operator. The notes and decision criteria in this Standard can be of a general nature only. Information on stormwater treatment in a separate system can be found in the ATV Report "Recommendations for treatment when handling stormwater" [12].1 Modified Combined System The modified combined system is a variant of the combined system. well. The precipitation water not requiring treatment is discharged directly into a lake or river or precipitated in situ after removal. With this an as comprehensive as possible water pollution control is to be achieved at reasonable cost. Not requiring treatment are. stormwater overflows or stormwater retention facilities are installed at suitable points in the combined system. 2. the combined sewer. traffic loading and how often the parking lots are frequented. The discharge of nonpolluted water such as spring. Only domestic and trade effluent as well as precipitation water requiring treatment are fed to the combined sewer. this combined wastewater is discharged and treated. December 1997 5 . land drainage water.2 Separate System In the separate system domestic wastewater and trade effluent are discharged in the normal sewer and precipitation water in the stormwater sewer.such as runoffs from external areas. 2. springs. springs and wells etc. December 1997 6 . land drainage water. discharge. percolation. Sewer Combined water treatment and retention Sewage treatment plant Retention. springs and wells etc.ATV-A 105E Discharge from sewered areas Qs Domestic and commercial wastewater Qr Precipitation water requiring treatment Precipitation water not requiring treatment Runoff from external areas. land drainage water. land drainage water. Comb. Sewer Combined water treatment and retention Sewage treatment plant Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers Fig. utilisation Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers Fig. springs and wells etc. 2: Schematic diagram of modified combined system drainage Discharge from sewered areas Qs Qr Runoff from external areas. 1: Schematic diagram of combined system drainage Discharge from sewered areas Qs Domestic and commercial wastewater Qr Precipitation water requiring treatment Precipitation water not requiring treatment Runoff from external areas. Comb. 4: Schematic diagram of modified separate system drainage 2. December 1997 7 . land drainage water. Normal sewer Sewage treatment plant Stormwater treatment and retention StormW drain Retention. percolation.ATV-A 105E Domestic and trade effluent Precipitation water requiring treatment Precipitation water not requiring treatment Normal sewer Sewage treatment plant Retention. discharge.2. discharge. 3: Schematic diagram of separate system drainage Discharge from sewered areas Qs Domestic and trade effluent Qr Precipitation water requiring treatment Precipitation water not requiring treatment Runoff from external areas. Precipitation water not requiring treatment is percolated or discharged into a surface body of water immediately at source or after diversion. utilisation StormW drain Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers Fig.1 Modified Separate System With the modified separate system domestic wastewater and trade effluent are fed to the normal sewer. percolation. utilisation Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers~~~~~~Lakes~~~~~~Rivers Fig. springs and wells etc. this is fed in a stormwater drain to a stormwater treatment facility. 3. The water management objective today is. flooding levels and quality of the lake or river. retention separate system). Essential criteria for the selection of the drainage system are: − type. the discharge of precipitation water is to be delayed and throttled using suitable measures (retention combined system. − water protection zones. the existing and future discharges from the catchment area as well as the suitability of the lake or river or the sewage treatment plant and. The selection and effects of the respective drainage system are to be integrated early in the project management planning. material preloading of the ground. The results of individual planning tasks. Wastewater and precipitation water requiring treatment are to be removed and treated. Both combined systems as well as separate systems have advantages and disadvantages Separate and combined systems are to be assessed. flooding areas. to percolate or to discharge directly to a surface body of water. if required. precipitation water not requiring treatment. − position.ATV-A 105E Insofar as precipitation water requiring treatment cannot be avoided. as far as possible. 3 3. should be summarised as negotiation concepts. structural condition. stormwater utilisation. groundwater levels. of the hydraulic efficiency of the existing system. acceptance capability. Here the drainage system and sewage treatment plant are to matched to each other. The drainage and charges bylaws are to be matched to the solution for the drainage system (hard surface area. hydraulic efficiency of the existing system.1 Criteria for the Selection of Drainage Systems Principles The objective of municipal drainage have changed significantly in recent years. including costs and time sequence. − percolation capability. In some German Federal States they comply with legally laid down wastewater disposal concepts and/or plans. from a water quality management aspect. Information on the treatment of stormwater can be found in the ATV Report "Recommendations for treatment when handling stormwater" [12].2 Local Conditions The planning of a sewer system depends on the topography. − topography. − type and density of the buildings. As a rule in the past the total precipitation runoff from built up areas has been discharged as completely and as rapidly as possible. December 1997 8 . as being equal (see ATV Standard ATV-A 128 [2]) The selection of the drainage system is to take place within the scope of initial planning. − characteristics of the discharges into the system. separate scales of charges). If necessary. the type of buildings to be connected. − with a high proportion of precipitation water requiring treatment. 4. stormwater settling tanks and percolation facilities are to be examined carefully according to local conditions already at an early stage of planning.3 Technical Aspects Below are listed selection criteria for both the normal drainage systems. − in combination with wastewater lagoon systems [3]. whereby attention is to be paid to servicing and maintenance of the drainage systems and the effects on the sewage treatment plant and lake or river. Separate systems are suitable: − with close rivers or lakes − for small gradients. − with tight construction conditions.ATV-A 105E − type and efficiency of existing sewage treatment plants. Table. − small sewage treatment plants with wastewater aeration for connection values between 50 and 500 PE [5]. The modified systems represent variants with which specific constraints must be met. − the employment of pressure and vacuum drainage systems [6]. The necessary areas are to be identified with project management planning. high groundwater level. With separate collection of wastewater and precipitation water (separate system) both types of wastewater can be discharged and separately treated according to their different quality and quantity. Comparative investigations. 1: Criteria for the selection of the drainage system Separate system Combined system December 1997 9 . Combined systems are suitable: − with distant lakes and rivers. which are described in more detail in Chap. The arrangement and design of stormwater overflows. 3. − for good gradients. − with a high proportion of precipitation not requiring treatment. − with staged expansion of the sewer network. As a rule the criteria have a decisive influence on the economy of the system. According to ATV Standard ATV-A 200 [10] separate systems are to be employed with: − small sized sewage treatment plants in accordance with DIN 4261 [4]. taking into account the construction and operating costs should be undertaken. − with small technical sewage treatment plants or wetlands. retention space. Table 1 summarises the criteria which are to be taken into account with the selection of the drainage system. ATV-A 105E 1. Sewers to lake or river Short Long 5. Pollution of surfaces Residential areas Industrial-commercial areas 2. Roads. Sewage treatment plant with Good buffer effect Poor buffer effect 4.= application not possible/not suitable x x with extensive SW treatment x with extensive SW treatment December 1997 10 . Settlement density High Low 8. lanes Wide Narrow 9. Wastewater inflow from external areas x None x Large x Large with heavy pollution x = application possible/suitable . Separation of types of wastewater Very possible Barely possible x without SW treatment x with SW treatment x x x x x with SW treatment x x x x x x x x x x - x x x with extensive SW treatment x x x x x x x x - x 10. Loading capacity of the lake or river High Medium Low 3. Gradient in catchment area Slight Good 6. Groundwater level High Low 7. 5 Planning. with drinking water pipelines which have to be laid at the same height or depth to parallel running wastewater pipelines. All sewers.ATV-A 105E 3.separate or combined . be above flooding levels so that. Thus. near natural extension of the lake or river). should be laid deeper than the supply lines. If this cannot be achieved without great expense. the probable duration of a flooding event and the size of the sewage treatment plant (scale of the loading of lakes and rivers when taken out of service). appropriate protective measures are to be taken. The frequency HWn is to be determined dependent on the hazard potential. A conscientious and professional supervision is absolutely necessary with the construction and operation of sewerage systems . Necessary measures are to be matched to each other (retention measures.4 Cost Aspects The economic efficiency of the selected drainage system has great significance. as far as possible. no back-up in the sewer system takes place. The selection of the drainage system and the arrangement of discharge points can significantly influence the discharge behaviour into the lake or river. The weir crown of overflow structures should. the laying of the supply pipeline in an appropriately long jacket pipe can be practical from a technical and economic point of view rather than a diversion. with flooding.if required with the respective modified systems. 3. a minimum separation of 1 m is to be maintained and the possible wastewater percolation cone is to be taken into account. existing drainage networks then the existing system. The throttle flow set is to be examined at regular intervals for its agreement with the level of connections and the efficiency of the sewage treatment plant.in particular with separate systems due to possible bad connections as well as with open discharge and percolation facilities. with high financial expense. Under certain preconditions the updating of a separate system. if necessary. Stormwater overflows in existing sewer systems must be checked against the objectives of ATV Standard ATV-A 128 [2] and. renewed. It must be verified in each design. even stormwater sewers in a separate system. The verification of the economic efficiency must be carried out with the inclusion of construction and operational costs as well as the investment dates [7]. modified. With this not only the costs of the public drainage system but also those for the necessary expenses for the private property drainage are to be taken into account. If it is necessary to renovate. With hydraulic overloading of networks it is also to be investigated whether the decoupling of areas and/or the creation of retention space are cost effective. for example with the employment of pressure or vacuum drainage for the discharge of wastewater with the retention of the existing network for stormwater discharge. Construction and Operation Within a defined drainage area as far as possible only one drainage system . should be employed. is more cost effective that the basic renovation of the existing sewers [6]. On undercutting this minimum separation or with the crossing of a sewage drain. for example. should be examined for its efficiency. December 1997 11 . Channels. in order to achieve the same impoundment frequency. 4.ATV-A 105E 4 Modified Drainage Systems There are several possibilities for modification.1 Separate Discharge of Precipitation Water Precondition for this is a body of water in the vicinity of the drainage area. intensive discussion with the owners. open channels and troughs near the surface require lower frequencies for the design rainfall than lower-lying closed pipelines. From experience they are frequently misused for dumping rubbish. − separation between the highest groundwater level. troughs. Otherwise advanced treatment measures will be necessary with the release of combined water from the sump system [2]. They are a part of green areas and can be considered as balancing measures within the framework of the testing of environmental compatibility. often with intermediate retention elements such as. active soil zone of at least 0. whereby these cover only the non-treated part of precipitation water: − separate discharge of precipitation water.2 Decentralised and Semi-centralised Percolation of Precipitation Water With decentralised percolation the percolation systems are close to the source. and the base of the percolation system of at least 1 m. With open discharge systems the following is to be observed: − in comparison with conventional drainage they require additional space and increased maintenance resources. With combined systems the mixing rate laid down in Chap.2 m thickness with an area/trough percolation system. for example. open trenches with flat slopes. With troughtrench systems retention. − use of percolation water. December 1997 12 . − with regard to hydraulic dimensioning it is to be noted that. Within the framework of the modification of the drainage system. turfed troughs. The successful implementation of a decentralised/semi-centralised percolation presumes previous. The separate discharge takes place in channels. 9 of ATV Standard ATV-A 128 may not be undercut. The following aspects are to be noted: − permeable subsoil with kf values between 10-3 and 5 x 10-6 m/s. percolation and discharge are combined together. trenches and ponds are also employed to improve the town planning or landscaping formation of residential areas. − trenches with steep slopes are difficult to look after and are susceptible to erosion. − a covered. the concentration of the combined water or stormwater in the remaining sump system increases. with semi-decentralised percolation several adjacent property owners operate a common percolation system. ponds. − percolation of precipitation water. raised by the percolation. As a result discharges are loaded with high solid contents. pipes. 4. operation and maintenance are the responsibility of the property owners. A separation of 6 m from buildings and 3 m from property boundaries are not to be undercut. humus content > 2 %).3 Central Percolation Central percolating systems percolate precipitation water of a larger catchment area.1) 4. the loading of the groundwater with pollutants increases. operation and maintenance as a rule is the responsibility of the commune. primarily if overflow capacity in the form of rainwater barrels and cisterns is connected. Attention is drawn to the hygienic considerations emphasised at various points. trenches.ATV-A 105E − flat troughs with a percolation area of As of at least 7 % of the effective discharge area Ared (Ared : AS > 15:1). pipes and porous paving neutralises the purification effect of the active soil layer. − no treatment of percolation systems and effective discharge areas with salt. − minimum requirement on the soil properties of the active soil zone (pH value > 6. 4.4 Use of Precipitation Water A third route to the modification of a drainage network consists of the utilisation of precipitation water. December 1997 13 . If a significant element of precipitation requiring treatment is contained in the runoff. herbicides. The operational life of the percolation system is shortened. 4. Through this the danger of a colmation (self-sealing) increases considerably due to pollutants in particulate form in the percolation water. The risk of a cellar flooding is to be examined. The percolation method frequently favoured by owners via shafts. The necessary treatment can be ensured in accordance with the statements of the ATV Report "Treatment recommendations for the handling of stormwater" [12] or through equivalent measures. − construction. grass fertiliser. Construction. The areas necessary for percolation are to be indicated with construction planning (see also Chap. A significant reduction of the stormwater runoff exists only if an allyear-round permanent usage for toilets and washing machines is guaranteed. clay content > 5 %. It is recommended that the course of seepage lines is followed by expert soil appraisals. The utilisation for watering gardens relieves the drainage network to an insignificant degree only. The above mentioned requirements apply analogously also for decentralised percolation of precipitation water from public roads. it must be treated before percolation to protect the groundwater and for the avoidance of colmation. Due to the high cost relevance it is precisely the precipitation water discharge which must be considered already with the identification of construction sites and also with the planning of private property drainage systems so that the areas so to be connected are kept small or are covered. in accordance with DIN 1986 is to be carried out. Even with the combined system a separate collection in the building.ATV-A 105E 5 Requirements on Private Property Drainage Private property drainage must be matched to the drainage system and the drainage bylaws and correspond with DIN 1986 [8]. Bibliography DIN EN 752 Drain and Sewer Systems outside Buildings. An increase of the infiltration water amount in the sewer system and in the sewage treatment plant has to be reckoned with. but are to be closed off or the water is to be discharged separately. Construction and Operation of Wastewater Lagoons for Communal Wastewater. Issue 10/89 DIN 4261 Small Sewage Treatment Plants [2] [3] [4] December 1997 14 . 6 1] Relevant Regulations. Issue 04/92 ATV-A 201E Principles for the Dimensioning. To ensure this the planning documents for the private property drainage should be checked before implementation and the correct implementation approved before taking into service. The pipelines are connected together first outside the building [8].Generalities and definitions Part 3 . Possible existing land drainage pipelines may not be connected to the public wastewater or combined wastewater network (infiltration water). With the separate system the precipitation water and the wastewater in the private property drainage system are to be discharged in two separate pipelines. Precipitation water from commercially or industrially used courtyards or hard surface traffic areas with heavy pollution is basically to be fed into the sewer system. Part 1 . with usage of cellar level seepage lines for the percolation via land drains in catchment areas.Planning ATV-A 128E Standards for the Dimensioning and Design of Stormwater Structures in Combined Sewers. with separate control shafts or control pipes with inspection and cleaning ports. This is to be taken into account with the determination of drainage systems and the wastewater treatment system. With projects in the area of the groundwater cellars are to be built watertight. 1 „Hinweise zur Versickerung von Niederschlagsabflüssen“ [Notes on the percolation of precipitation runoff] (Not available in English). 1995 (Not available in English). KA 02/94 ATV Report of ATV Working Group 1. Berlin [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] December 1997 15 . Verlag Wilhelm Ernst & Sohn.4. KA 05/95 ATV Handbook „Planung der Kanalisation [Planning of sewer systems] 4th completely revised edition. Issue 05/97 ATV Report of ATV Working Group 1.3 „Umgang mit Regenwasser . 1994 (Not available in English).ATV-A 105E [5] ATV-A 122E Principles for the Dimensioning.3 „Handlungsempfehlungen zum Umgang mit Regenwasser“ [Treatment recommendations for the handling of stormwater] (Not available in English).Pressure Drainage Service.derzeitiger Stand der Regenwasserbehandlung im Trennsystem“ [The handling of stormwater . KA 08/96 ATV Report of ATV Working Group 1. Issue 01/90 ATV-A 200E Principles for the Disposal of Wastewater in Rurally Structured Areas. Verlag Wilhelm Ernst & Sohn. Construction and Operation of Small Sewage Treatment Plants with Aerobic Biological Purification Stage for Connection Values between 50 and 5000 Total Number of Inhabitants and Population Equivalents Issue 06/91 ATV-A 116E Special Sewer Systems .the current status of stormwater treatment in the separate system] (Not available in English). Berlin ATV Handbook „Bau und Betrieb der Kanalisation“ [Construction and operation of the sewer system] 4th completely revised edition. Issue 09/92 "Leitlinie zur Durchführung von Kostenvergleichsrechnungen" LAWA 1993 (Guidelines for the execution of cost comparison calculations)(Not available in English) DIN 1986 Site Drainage Systems for Buildings and Private Properties ATV-A 138E Construction and Dimensioning Facilities for Decentralised Percolation of Nonharmful Polluted Percolation Water.4.Vacuum Drainage Service .4.