PROGRAM FOR WATER AND WASTEWATER OF KARLOVAC CITY: VERIFICATION OF THE EXISTING DRAINAGE SYSTEM OF KARLOVAC CITY, CROATIA

Transcription

1 PROGRAM FOR WATER AND WASTEWATER OF KARLOVAC CITY: VERIFICATION OF THE EXISTING DRAINAGE SYSTEM OF KARLOVAC CITY, CROATIA HYDRAULIC CALCULATION BY MEANS Of THE MATHEMATICAL MODEL OF THE EXISTING AND FUTURE SITUATION WITH TECHNICAL ANALYSIS OF THE VERSIONS' SOLUTIONS B.Sc. Draženka Kvesić, civ. eng. PRONING DHI d.o.o., Račkog 3, Zagreb Croatia. Contact author B.Sc. Vesna Rogulja, civ. eng. PRONING DHI d.o.o., Račkog 3, Zagreb Croatia. Key words: MOUSE, mathematical model, measurements, calibration, existing and future situation ABSTRACT In the area of Karlovac city is no complete sewerage system and untreated wastewater is discharged at several locations into the closest water flow. In order to protect the water flow and in order to satisfy Croatian and European regulations, this project is one of the actions which will lead to the construction of an entire system of drainage and wastewater treatment in the area of Karlovac and Duga Resa. The model of the Karlovac sewerage system has been done with the hydraulic calculation and the mathematical model. The approach of solving the given issues is based on the application of methodology and approach, which are included in the technology of the MOUSE. During the simulation, two hydrological-hydraulic scenarios have been used: - for the existing situation - for the future situation Hydrological-hydraulic measurements have been conducted at the catchments and structures of the sewerage system in order to develop a model of the existing state and the conduction of the discharge simulation in the Karlovac sewerage system and its calibration. Six meters have been installed in the sewerage system and six ombrographs as displayed on the schematic layout on the following figure. As there are several different structures at the existing sewerage system of Karlovac city, their number will even more increase in the future. It is planned to construct even more pumping stations, overflow structures, siphon crossings and stormwater tanks.

2 1. INTRODUCTION Karlovac is Croatian city 50 km southern of Zagreb, has inhabitants with four rivers Kupa, Korana, Mrežnica and Dobra. In the area of Karlovac city is no complete sewerage system and untreated wastewater is discharged at several locations into the closest water flow. In order to protect the water flow and in order to satisfy Croatian and European regulations, this project, i.e. one part of it, is one of the actions which will lead to the construction of an entire system of drainage and wastewater treatment in the area of Karlovac and Duga Resa. The model of the Karlovac sewerage system, namely of the existing state of development, has been done with the hydraulic calculation and the mathematical model. Afterwards, the model of the future situation has been done. 2. METHODOLOGY The approach of solving the given issues is based on the application of methodology and approach, which are included in the technology of the MOUSE. "IDF" curves have been used for the requirements of this project. During the simulation, two hydrological-hydraulic scenarios have been used: - for the existing situation (existing city development and existing sewerage system development), - for the future situation (planned city development and planned sewerage system development). 3. MATHEMATICAL MODEL OF THE EXISTING SITUATION The mathematical model of the existing situation consists of the hydrological model and the hydraulic model of the existing situation. This means that all input data as well as all data bases are border requirements that have been defined during the elaboration of the mathematical model at the beginning of INPUT DATA In order to create the mathematical model, data on population, water consumption, industry, geometrical data on the sewerage system, including data on channels and structures and hydrological data have been used as input data. Total number of population is , connecteted to the water supply network is inhabitions. Daily wastewater quantity per inhabitant is 127 l/inh/day. The following Data on geometrics of the existing drainage system sources have been used:

3 1. Outline in ACAD format with marked channels of profile larger than 60 cm by "Vodovod i kanalizacije" Karlovac. 2. Outline in ACAD, 5000 with contour lines 3. GIS of the sewerage system (incomplete) The total water consumption, which has been delivered to the business sector in 2006, is m3/s. The biggest one is Karlovac brewery with m 3 /annual wastewater in and 0,0163 m 3 /s. The Karlovac brewery operates in three shifts with higher production during the summer and before Christmas CONCEPT AND SCHEME OF THE SYSTEM The sewerage system Karlovac consists of several subsystems, out of which each one has its own outlet into the river Kupa or Mrežnica, the subsystems are as follows: - subsystem GRAD Inhabitants, total catchments area: 722 ha, one outlet - subsystem Drežnik Inhabitants, total catchments area: 34 ha, two outlets - subsystem Banija Inhabitants, total catchments area: 117 ha, two outlets - subsystem Borlin- 800 Inhabitants, total catchments area: 20 ha, one outlet - subsystem Velika Švarča Inhabitants, total catchments area: 40 ha, with two outlets - subsystem Southern channel - mainly industry area, with three outlets These subsystems are independent from each other, which mean that they do not have a point of contact. Some of them consist of their own subsystems as in the case of the southern channel subsystem. The HYDRAULIC model has been acquired after the schematization of the detailed model and represents the geometry of the Karlovac sewerage system with the current state of development (2007); it consists of: 398 nodes; 1 overflow; 1 pumping station; 10 outlet; 406 pipes MEASUREMENTS Hydrological-hydraulic measurements have been conducted at the catchments and network of the sewerage system in order to develop a model of the existing state and the conduction of the discharge simulation in the Karlovac sewerage system and its calibration. These measurements are conducted by a specially trained and equipped team from the IGH Company. SIX flow meters have been installed in the sewerage system and SIX ombrographs as displayed on the schematic layout on the following figure.

4 Figure 1 FLOW METER (RJEČKA) (VOJARNA) The measurements that PRONING DHI d.o.o. has taken over from IGH are for the time period , which is in total seven months, whereof test measurements have been conducted throughout the first month. Based on the conducted analysis of the quality of measurement results, it has been determined that it is not possible to use all data from the measurement period. Ombrographs from Gaza, Grabrik and Borlin have been used for the calibration of the mathematic model of Karlovac city CALIBRATION The calibration has been conducted on the model of the Karlovac sewerage system with the existing situation of development and measurement data which were available to us. Since no meter devices could be placed at the subsystems Banija and Drežnik, which would reliably measure the flow, five meters were set up at the subsystem "GRAD". One additional meter device was set up at the southern channel. Since the southern channel has not been mathematically modeled, the meter is not used at the calibration of the mathematical model. This means that for the calibration of the mathematical model of Karlovac city- subsystem "GRAD", the following meter devices have been used: "Gaza", "Jamadol", "Luxor", "Kod Vojarne" and "Riječka cesta". The ombrographs used for the calibration of the subsystem "GRAD" are "Gaza", "Grabrik and "Borlin".

5 Dry weather flow calibration Dry weather flow, as known, consists of industrial water, population and infiltration water. The precise flow from population has been calculated after the calibration, q st =127 l/inh/day. Information on industrial water is gained from the pollution register, while infiltration water is not known, but it is assumed that they make up ca % of the dry weather flow. The total dry weather flow is examined with daily oscillations. The dry weather flow has been calibrated on the basis of measurements in the dry weather period. The period from April has been selected, when no rain was recorded, from the gathered data on measurements. Table 1 - Recorded values of flow for the dry weather period: Measurement location Qmin (l/s) Qmax (l/s) Qaver. (l/s) Gaza Luxor Jamadol Barracks (Vojarna) Riječka The final simulation results are displayed in the figures: Figure 2 Comparison of the simulated and measured flow at the measure location Gaza [m3/s] Time Series DISCHARGE BRANCHES (SUH3-21.PRF) DISCHARGE BRANCHES GAZ GAZ DISCHARGE - gaza_q Figure 3 Comparison of the simulated and measured water depth at the measure location Gaza [m] 0.60 Time Series DEPTH (SUH3-21.PRF) DEPTH GAZ-804 WATER LEVEL - gaza_h Figure 4 Comparison of the simulated and measured flow at the measure location Rječka cesta [m3/s] Time Series DISCHARGE BRANCHES (SUH3-21.PRF) DISCHARGE BRANCHES GRA-MM -- GRA DISCHARGE - rijecka_q Figure 5 Comparison of the simulated and measured water depth at the measure location Rječka cesta [m] Time Series DEPTH (SUH3-21.PRF) DEPTH 158 WATER LEVEL - rijecka_h

6 Calibration of the total flow Approximately 20 rains have been recorded over the six months of measurement that have been recorded by all ombrographs. This means that there was rain in the entire monitored catchments area. The final simulation results for two rain events at two locations are displayed in the figures: Figure 6 Comparison of the simulated and measured flow at the measure location Gaza - 2. March 2007 Figure 7 Comparison of the simul. and measured water depth at the location Gaza - 2. March 2007 [m3/s] Time Series DISCHARGE BRANCHES ( PRF) DISCHARGE BRANCHES 2.0 GAZ GAZ DISCHARGE - gaza_q [m] Time Series DEPTH ( PRF) DEPTH GAZ-804 WATER LEVEL - gaza_h :00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00 00:00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00: Figure 8 Comparison of the simulated and measured flow at the measure location Rječka cesta-19. March 2007 [m3/s] Time Series DISCHARGE BRANCHES ( PRF) DISCHARGE BRANCHES 0.70 GRA-MM -- GRA DISCHARGE - rijecka_q Figure 9 Comparison of the simul. and measured water depth at the location Rječka cesta- 19. March 2007 [m] Time Series DEPTH ( PRF) DEPTH 158 WATER LEVEL - rijecka_h :00:00 12:00:00 18:00:00 00:00:00 06:00:00 12:00:00 18:00:00 00:00:00 06:00:00 12:00:00 18:00:00 06:00:00 12:00:00 18:00:00 00:00:00 06:00:00 12:00:00 18:00:00 00:00:00 06:00:00 12:00:00 18:00: MATHEMATICAL MODEL OF FUTURE SITUATION Through the development of Karlovac, its expansion, built up and by planning the construction of a wastewater treatment plant, the look and concept of Karlovac sewerage system changes. Several concepts had been analyzed by the mathematical modeling on possible development of the sewerage system with the aim to bring wastewater to the plant INPUT DATA Input data has already been gathered and used at the elaboration of the mathematical model of the existing situation, with that that additionally all data has been used which

7 influences the change of incoming / border conditions for modeling the Karlovac sewerage system. Data on population figures planning, wastewater consumption and industry development have been used from the input data in order to create the mathematical model of the future situation. Geometrical and hydrological data on the sewerage system, which is from the existing documentation, is also used. Urbanistic layouts that show the city development planning, the Urban General Plan of Karlovac, are very significant CALCULATION OF RELEVANT QUANTITIES OF DRY WEATHER FLOW AND RUN-OFF The calculation of relevant dry weather and rainwater flow, as well as calculations of all other parameters connected to the dimensioning of channels and sewerage system structures is based on the ATV norm and the calculated daily quantity of wastewater per resident of 130 l/inh/day. With regard to the fact that wastewater of twice the size of the dry weather flow is brought to the wastewater treatment plant of Karlovac, as well as to maintain the critical flow and bring it to the treatment plant, it is necessary to define the sizes of the retention volume on each rain overflow which should accept these quantities. ATV norms A 128 from 1992 have been used for the calculation of the required volumes. The relevant quantities of dry weather flow, through which the flow in the Karlovac sewerage system for the future development is modeled, are displayed in the following table. Table 2 Subsystem: Qinhab. (l/s) Qind. (l/s) Qinf. (l/s) CITY (GRAD) Drežnik 1,8 1 0,9 northern Banija 3 1,5 1,4 southern Banija 4,5 1,5 1,8 Švarča and Mostanje 1,8 0,5 0,7 PPK channel ,5 Relevant quantities of rainwater are defined by using the simulation for IDF rain of the reversible period of 3 years, duration 20 minutes. The quantities for each main channel are defined through the mathematical simulations, as well as the structures of the system CONCEPT AND SCHEME OF THE SYSTEM MATHEMATICAL MODEL OF THE FUTURE SITUATION During the elaboration of the project a number of concept versions on the future situation of the Karlovac sewerage system have been worked out. There were a number of limiting factors while defining the concept of the system, which arose from the need to preserve some cultural heritage of the old city Karlovac- Zvijezda. According to the protection

8 requirements for the old town Zvijezda, it is necessary remove all major works, structures and channels from that zone. With that, to define the concept of the system has been partly limiting, because the most convenient hydraulic solutions couldn't be entirely satisfied. Figure 10 Schematic lay-out of the proposed concept solution for the Karlovac sewerage system 4.4. MAIN FEATURES OF THE DEVELOPMENT PLAN FOR THE KARLOVAC SEWER SYSTEM The following will give the most important characteristics of the concept solution for the planned development of the discharge system of Karlovac according to the proposed version, as well as describe planned structures, as a result of the mathematical model of the sewerage system. Here are all data in one place, which will be required for further designing and which refer to the following: Table 3 - Dry weather and double dry weather flow for each subsystem: Relevant values Subsystem Qs (l/s) 2Qs (l/s) CITY (GRAD) Drežnik 8 15 CITY (GRAD) + dry weather Drežnik Banija northern 12,2 23 Banija southern PPK-before the river Kupa Pumping station before the river Korana "lift station" Švarča 5,5 10,2

9 Table 4 - Features of stormwater overflows: Overflow structure Max. flow for relevant event (IDF 3 years 20 min) accumulated volume for relevant event (IDF 3 years 20 min) V (m3) Planned crest level Orientation width of overflow sill Qov C. L. (m3/s) (m as/l) Internal overflow in node 24 4, ,30 6 Internal overflow in node 487 1, ,30 5 Overflow GRAD before Kupa 6, ,00 10 Overflow northern Banija 0, ,50 5 Overflow southern Banija 0, ,50 10 Overflow Drežnik 0, ,20 5 Overflow Švarča 0, ,20 4 B (m) Table 5 - Size of the stormwater tank: Subsystem Necessary retention volume Existing available retention volume Required retention volume to be constructed Vnec. (m3) Vex. (m3) Vcon. (m3) CITY (GRAD) Northern Banija 150 / 150 Southern Banija 180 / 180 Drežnik 110 / 110 Švarča 120 / 120