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

2. 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

3. Example of a mixing zone
Small heat discharge of high temperature
Heat discharge 1
Heat discharge 2
Intake2
Intake 1
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4. 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

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

6. 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

7. 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

8. 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

9. 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)

10. 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..)

11. 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

12. 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

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

14. 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

15. 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

16. 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!

17. 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

18. 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

19. 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

20. Questions?