Introduction to Discharge Test Software Mixing zones Introduction to Discharge Test Software Dju Bijstra (NL)

Contents Tiered approach Tier 2: discharge test Worst case approach starting points limitations application of discharge-test (software tool) (example) developments of discharge-test in the Netherlands

Example of a mixing zone Small heat discharge of high temperature Heat discharge 1 Heat discharge 2 Intake2 Intake 1 15| 16| 17 | 18| 19| 20| 21| 22| 23| 24| 25| 26| 27| 28| 29| 30|

Tiered Approach (1) TIER 0: Are prioritary substances present in the discharge in concentrations >EQS? NO  Stop TIER 1: is the discharge significant? NO  Stop Yes

Tier 1 STOP Yes Can criteria in table be met? No GO TO TIER 2

Tiered Approach (2) TIER 0: Are prioritary substances present in the discharge in concentrations >EQS? NO  Stop TIER 1: is the discharge significant? NO  Stop TIER 2: determination of mixing-zone whith the discharge-test: are dimensions of MAC-MZ and/or EQS-MZ bigger than criteria proposed? NO  Stop TIER 3: Complex modelling: Is MZ a problem? NO  Stop TIER 4: Local (effect)assessment (i.e. bioassays) (optional): Is MZ a problem? NO  Stop Yes Yes NL-discharge-test measures or Yes measures or Yes measures Yes If necessary new complex modelling

EXPERT DETAILED RESEARCH Discharge test (1) Fast and easy No problems Little info needed Worst case conditions: Q90 and max. load sieve EXPERT DETAILED RESEARCH Time consuming Lots of data needed Potential problems Option: Go to Tier 3 or 4

Concentration at predefined or user Discharge test (2) Input: Q90 flow of water body and max. load of discharge Water body data: Width, depth,bottom- roughness Discharge test Fisher equations Concentration at predefined or user defined distances Dimensions of mixing zone LMZ ≤ Lpredefined? CL ≤ MAC or EQS? Can criteria be met? yes no Activity can be permitted no Tier 3 and 4 More detailed information concerning the water body and/or discharge is needed. Complex assessment (e.g. complex models) Take supplementary measures no yes Can criteria be met? Activity can be permitted

Concentration at checkpoint L: Distribution pattern X- axis Concentration at checkpoint L: CL=EQS C Point of dicharge Distribution pattern: In this slide the distributions pattern as a function of the distance to the discharge point is shown. Mixing in the Y-direction rectangular to the flow direction increases when the distance to the discharge point increases.The EQS is given by the red rectangles. The red dotted line gives the concentration as a function of the distance to the discharge point at the river bank.At checkpoint at a distance L from te point of discharge the conecntration in the surface water has to meet EQS. depth Y-axis (water body)

Discharge test and WFD X1 CL=EQS X2 CL=EQS Point of monitoring flow XL Cb+Cb Cb X P2< P1 P1=allowable load Discharge-test can be used as tool to achieve WDF-standards at water body level In general X >> XL (size of the mixing zone) and therefore dilution at monitoringspoint >> than at X2 and X1 Attention!: for relative large discharges at small waters complete mixing can be achieved whithin the mixing zone! Space for extra discharges in that case, depends on substance properties (e.g. biodegradability, volatility etc..)

Mixing zones in fresh waters View from above Direction of flow X ≤ XMAC EQS 1,5 EQS 2EQS MAC XL ≤ predefined allowable length XEQS C > MAC Cross-section waterbody at black dotted line C > MAC MAC 2EQS 1,5EQS EQS Migration is guaranteed

Criteria EQS mixing zone: 10*width of the waterbody with a maximum of 1000 m MAC mixing zone: 0,25*width of waterbody with a maximum of 25 m In the discharge test an option has been taken up for giving in a user defined length of the mixing zone Attention!: when using other dimensions for the mixing zone, than predefined in the discharge test, it has to be checked whether or not WFD standards at water body level still can be achieved

Discharge test (3) Limitations NOT (specific) FOR: Coastal waters Open sea Tidal rivers (Tidal) harbours

Application of Discharge test (example) Q90 flow = 15 m3/s Cb = 1 mg/l Discharge flow: 275 M3/h Concentration: 100 Mg/l Criteria: EQS: 2 mg/l MAC: 10 mg/l Depth: 3 m Width : 30 m Example will be worked out for two watertypes: river river with high bed roughness

Input discharge test Water body: Flow: 15 m3/s Cb: 1 mg/l width: 30 m Depth: 3 m (2 m) Discharge: Flow: 275 m3/h Cdischarge : 100 mg/l Pipe-diameter: 0,2 m Criteria: MAC: 10 mg/l EQS: 2 mg/l Snelkoppeling naar IM-toets-1.3(niet gebl)-english-new-9.xls

Conclusions example Water body characterics do matter! River (Chezy = 50)  necessary reduction: 31% River (high bed roughness) (Chezy = 23)  necessary reduction: 15% Normal river River with high bed roughness (99) (67) EQS mixing zone is limiting! MAC mixing zone is limiting! Water body characterics do matter!

Development of discharge test in the Netherlands 2009: inventory to the experiences with the discharge test in NL has been carried out Results: the following aspects have identified as bottleneck: - lack of water system data (water quality and quantity) - Mixing zones in (tidal) harbours and tidal waters (including coastal waters and open sea) cannot be calculated In NL a web-based application has been developed with modules for fresh waters, (tidal) harbours, tidal rivers, coastal water and open sea. databases with water system data can be coupled to the web-based application

Summary (1) and Water system characteristics: flow, Cbackground, dimensions, bed roughness Characteristics of the discharge: flow, Cdischarge, diameter pipe and location Flexible: User-defined options and Discharge test concentrations at predefined distances (XL and Xmac) and user defined distances X and the increase in concentration after complete mixing Dimensions of the EQS and MAC mixing zone

Summary (2) Simple Flexible Worst case But less appropriate for (tidal)harbours and tidal waters For these situations the web-based application is more appropriate

Questions?