Project area
• Zadar County, administratively: city of Zadar
• Project scope:
• WS & WW network
• WW treatment
Project base data
Agglomeration Zadar Petrčane
Population (2011.) 72.008 + 3.000 1.416
Tourism - overnights
20151.002.400 469.400
Tourism seasonality
July + August~55 % ~65 %
Total water consumption (m3/y),
2012 – 2015 average~4.900.000 ~200.000
Water consumption ratios (%)
households/tourism/industry68% / 27% / 5% 20% / 12% / 68%
Connection rate – WS ~99% ~99%
Connection rate – WW ~72% ~0%
Existing state – water supply
• Water intakes:
• Zrmanja river – main source
• Groundwater wells (secondary sources)
• Number of local intakes (auxiliary sources)
• Water supply system covers city of Zadar and 11
additional municipalities, including the suppy of several
islands
• Total network length – approx. 1.250 km
• 44 water tanks, 29 booster stations
• Total number of customers ~ 123.000Indicator Value
Total abstracted water
(m3/yr)28.976.000
CARL (m3/yr) 18.893.000
Real water losses - ILI 17
Non-revenue water 71,00%
Existing state – WS network
Northeastern direction of supply
(intake from Zrmanja)
Water tank Pudarica
Northwestern direction of supply
(intakes Jezerce, Bunari 4 i 5)
Water tanks Zadar I i Zadar II
Existing state – WW network
• 185 km of network + 20 PS
• Mostly mixed WW system
• 2 separate subsystems:
• Centre and Borik
• 2 WWTPs:• WWTP Centre
• 100.000 PE
• Secondary treatment
• WWTP Borik
• 15.500 PE
• Primary treatment
• Settlement Petrčane
• No public network
• 2 private networks withWWTPs (hotel complexes)
Existing state – identified issues
• Improvement of connection rates for agglomeration Zadar
• Insufficient connection rates a result of nonexisting system
• Around 25% of population doesn’t have access to WW system
• Hydraulic model of WW system showed bottlenecks in the system –
inadequate profiles
• 1,9 km of collectors to reconstruct
• Seawater intrusion in certain areas of Zadar (coastal collectors)
• Worst section identified in subsystem Borik
• 1,5 km of CIPP rehabilitation for coastal collectors included in STIP
• WW network and treatment in agglomeration Petrčane non-existent
Base design data
Agglomeration Zadar Petrčane
Population (2031) 76.900 + 3.000 1.500
Population consumption (l/cap/day) 110-140 110-140
Tourism - overnights 2031 ~1.260.000 480.000 (322.000)
Total consumption (m3/year)~5.185.000 ~235.000
Projected WW connection rates 90% 85%
WWTP load (PE)107.400 5.800
Recipient coastal sea - Zadar channel, "normal" sea
Treatment level required secondary "appropriate"
UWWTD deadline 2018 2023
Project scope and justification
- all agglomerations -
Measure Justification
WWTP in the project area Compliance with Urban Waste Water Treatment
Directive (91/271/EEC)
Compliance with requirements Croatian law
(Water Act)
• Implementation before end 2018/2023
• Normal area
• Minor upgrades on existing WWTPs to be
carried out
Extension of sewerage systems Increase the collection rate
Reconstruction of existing sewers Reduce sea intrusion
Improve hydraulic aspects
Reconstruction of water supply pipelines Impossible to avoid while constructing WW
network – estimate of 30% of WW network –
needs to be confirmed
Supervision Ensure supervision and FIDIC Engineer services
Project Management Mitigate lack of technical/administrative capacity
of the End Recipient
Option analysis carried out
Intervention Option analysis
WW network Pipeline routes in public corridors
Sewer rehabilitation based on CCTV records
No significant route options
WS network Pipeline routes in public corridors
No significant route options
WS reconstruction provided only for damaged
sections due to WW system construction (narrow
streets)
WWTP location for
agglomeration Petrčane
Two potential solutions analyzed
Sludge management and
disposal
Option analysis to be carried out
Preferred solution identified and quantified (for
discussion)
Option analysis – WW treatment for subsystem Borik
• Two main options considered:
• V1: Upgrade of WWTP Borik to secondary treatment (in accordance with
UWWTD)
• V2: Construction of transportation system from WWTP Borik to WWTP
Centre in Zadar and treatment on that location
• Comparison based on LCC (NPV, 30 years, 4% DR)
• In V1 – no available space for upgrade – not applicable
• 3 possible routes of transportation system analyzed
• Similar NPV results in all three proposed routes
• Route chosen due to comparative advantages with regards to installation crossings
(easy to build criteria)
• Mechanical treatment to remain in WWTP Borik – 5% reduction in
BOD calculated for loads coming into WWTP Centre
Option analysis – WW treatment for agglomeration
Petrčane• Two main options considered:
• V1: Construction of a new WWTP Petrčane, for capacity of 5.800 PE and
appropriate treatment level
• V2: Construction of transportation system to WWTP Centre in Zadar and
treatment on the existing location
• Comparison based on LCC (NPV, 30 years, 4% DR)
• In V1 – costs of WW network and CAPEX/OPEX of a new WWTP
• In V2 – costs of WW network, transportation system and OPEX for WWTP Centre
• V2 preferred and chosen
Recapitulation of variant solutions for agglomeration Petrčane NPV (HRK) Index
V1 –WWTP Petrčane 63.162.409
1,020WW system for settlements Petrčane and Kožino 40.288.768
New WWTP Petrčane, primary treatment (5.800 PE) 22.873.642
V2 – connection to WWTP Centre 61.937.665
1,000WW system for settlements Petrčane and Kožino 38.903.938
Transportation system from Petrčane to Zadar 19.979.308
OPEX for WWTP Centre (loads from agglomeration Petrčane) 3.054.419
Summary of loads on WWTP Centre
• Additional loads from subsystem Borik (5% reduction in BOD)
• Additional loads from agglomeration Petrčane
• Total calculated peak load – 110.000 PE (august 2031, seasonality factor
approx. 1,14)
• Nominal capacity of existing plant – 100.000 PE
• It is estimated that the existing plant can cope with exceeding loads (10% of
nominal capacity) in the projected period
• Exceeded loads are due to occur only in peak tourism season (10 days)
• If additional loads are to be received at WWTP Centre (agglomeration
Bibinje-Sukošan) upgrade would be necessary
200,00
225,00
250,00
275,00
300,00
325,00
350,00
375,00
85.000
90.000
95.000
100.000
105.000
110.000
115.000
120.000
1 2 3 4 5 6 7 8 9 10 11 12
l/sES
mjeseci
UPOV Zadar Centar - rezultati analize
Kapacitet (ES) Maksimalni satni dotok (l/s)
STIP summary
• WW system
• ~102,5 km of gravity collectors
• ~10,4 km of pressure pipelines
• ~5.300 connections (new)
• 20 pump stations
• WS system
• ~22,5 km of WS network (reconstruction due to WW construction)
• ~1.250 connections (reconnections)
• WWTP Centre and Borik
• Minor upgrades to WWTP Centre (no additional capacity)
• Replacement of ME equipment on WWTP Borik
Option analyses –sludge management
• To be fully carried out
• Sludge management
• preferred solution – transport to RWMC Biljane Donje
• FS for Biljani Donji took into account sludge disposal for
agglomerations Zadar and Petrčane
• Gate-fee calculated at 20€/tonne of sludge delivered to RWMC –
deemed as acceptable
• Transport from WWTP Centre to RWMC – to be included in this Study
Investment cost estimate
Component Investment estimate (HRK)
WW system construction/reconstruction – agglomeration Zadar 155.500.759
WS system reconstruction – agglomeration Zadar24.195.000
WW system construction/reconstuction – agglomeration Petrčane 64.435.427
WS system reconstruction – agglomeration Petrčane 6.893.000
SUBTOTAL 251.024.186
Supervision 12.551.000
Project Management 5.020.000
Visibility 750.000
Equipment supply 0
Contingencies (10%) 26.934.519
TOTAL (HRK) 296.279.705
Retrofit investments on WWTP Zadar Centre
1. Septic equalisation tank
2. Upgrade of odour treatment
3. Grit/grease trap and primary settlers to be covered
4. Replacement of diffusers in bioreactors
5. Technical water system to be added
6. Floating sludge issue
7. Potential for anaerobic sludge digestion