Anete Kubliņa

Latvian Environment, Geology and Meteorology Centre

Information Analysis Department

Inland Waters Division

Kaunas, 04.12.2014.

Modelled mixing zones in Latvian part of

Venta river basin district

ContentContentContentContent

� Description of hot spot selection;

� Description of discharges;

� Validation of modelling results;

� Summary of results of mixing zones modelling;

� Aizpute case;

� Conclusions.

Description of hot spot selectionDescription of hot spot selectionDescription of hot spot selectionDescription of hot spot selection

Used data sources:

• Data from “2-Ūdens” data base about all waste water discharges in

Venta RBD;

• State surface water quality monitoring results most up to date - of year

2013 or earlier, taking into account

� changed typology in frame of HOTRISK project.

Water sampling and water flow measurement sites in Venta

river basin district in framework of the project HOTRISK

Description of Description of Description of Description of dischargesdischargesdischargesdischarges (1)(1)(1)(1)

Tukuma municipal enterprise “Tukuma

ūdens” wastewater discharge site

description

Company “Tukuma piens” wastewater

discharge site description

Description of Description of Description of Description of dischargesdischargesdischargesdischarges (2)(2)(2)(2)

Company “Saldus Komunālserviss” wastewater

discharge site description Aizpute municipal enterprise "Aizputes

komunālserviss" wastewater discharge site

description

Description of Description of Description of Description of dischargesdischargesdischargesdischarges (3)(3)(3)(3)

Company “Kuldīgas ūdens” wastewater

discharge site descriptionVillage Novadnieki wastewater discharge site

description

Description of Description of Description of Description of dischargesdischargesdischargesdischarges (4)(4)(4)(4)

Village Venta waste water treatment plant

and wastewater discharge site descriptionEzere wastewater discharge site description

Description of Description of Description of Description of dischargesdischargesdischargesdischarges (5)(5)(5)(5)

Village Kusaiņi wastewater discharge site

description Village Iļģi wastewater discharge site description

Validation of Validation of Validation of Validation of modelmodelmodelmodelllllinginginging resultsresultsresultsresults

During the Project, there were done two rounds of measurements for mixing zones modeling purposes:

• 1st round for water quality measurements was done from 17.06.2014. to 26.06.2014., in the effluent

discharge and upstream the discharge place in river, where possible;

• 2nd round for water quality measurements was done from 05.08.2014. to 11.08.2014., in the effluent

discharge and downstream it in the modeled length of mixing zone or in the test criteria distance (10 * river

width).

1st and 2nd round measurements both were performed in summer low – water period, in which

• river discharge and flow of effluent discharge varies significantly between these two measurements;

• polluting substances concentrations in effluent are more comparable between those two rounds.

Validation of Validation of Validation of Validation of modelmodelmodelmodelllllinginginging resultsresultsresultsresults

• There were compared modelled and measured concentrations.

• Modelled concentrations were modelled with Excel discharge test, using actual river discarge

measurements (table 5.2.) and long-term minimal calculated river discharge (table 5.3.).

• Results show higher correlation coefficients, using actual measured river discharge values,

respectively, strong correlation coefficients – above 0.9 – is for Ntot., Ptot., Zn, Cu, about 0.7 for

chromium and Ni bioavailable, but medium – 0.44 – for Ni. There is no correlation for

chromium measurements.

Summary Summary Summary Summary of of of of mixing zones mixing zones mixing zones mixing zones modelmodelmodelmodelllllinginginging resultsresultsresultsresultsEffluent concentration comparing with EQS belongs to Tier 0 assessment according to Technical guidelines for the

identification of mixing zones pursuant to Art. 4(4) of the Directive 2008/105/EC.

EQS / limiting values exceedances were observed for such substances as :

� Ptot. (10 operators in 1st round, 10 - in 2nd round)

� Ntot. (9 operators in 1st round, 9 - in 2nd round)

� N/NH4 (6 operators in 1st round)

� N/NO3 (4 operators in 1st round)

� Ni (1 operator in 1st round, no operators - in 2nd round)

� Ni bioavailable (1 operators in 1st round, no operators - in 2nd round).

For other substances with EQS – Zn, Cu, As, Cr, phenols, formaldehyde, benzene, Cd, Pb - measured concentrations

were less than EQS.

Summary of results of mixing zones modelingSummary of results of mixing zones modelingSummary of results of mixing zones modelingSummary of results of mixing zones modeling

Modelled mixing zones of wastewater treatment plants

discharges for Ni., 1st round measurements

AA-EQS = 4 for bioavailable

concentration (directive 2013/39/EU)

AA-EQS = 20 (directive 2008/105/EC)

[VALUE] (60)

[VALUE] (60)

0 100 200 300 400 500 600 700 800 900 1000

Aizputes komunālais uzņēmums, TEBRA

m

Ni

Ni bioavailable

Ni

Modelled mixing zones of wastewater treatment plants

discharges for Ni., using Q90 data

How do mixing zones change,

when using long-term Q90 data?

[VALUE] (22m)

[VALUE] (750 m)

[VALUE] (40 m)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Saldus komunālserviss, DĪCMAŅU STRAUTS

Rumbas pagasta pārvalde, Ventas ciemats, VENTA

Aizputes komunālais uzņēmums, TEBRA

m

N/NO3

Modelled mixing zones of wastewater treatment plants discharges for Ptot., Ntot., N/NH4, N/NO3, 1st round

[VALUE] (60)

Cbackground > EQS (70)

Cbackground > EQS (22)

[VALUE] (200)

[VALUE] (600)

[VALUE] (750)

[VALUE] (4)

> [VALUE] (51)

0 200 400 600 800 1000

Tukuma piens, SLOCENE

Tukuma ūdens, SLOCENE

Saldus komunālserviss, DĪCMAŅU STRAUTS

Ezeres pagasta pārvalde, Ezere, VADAKSTE

Kuldīgas ūdens, VENTA

Rumbas pagasta pārvalde, Ventas ciemats, VENTA

Rumbas pagasta pārvalde, Novadnieku ciemats,…

Aizputes komunālais uzņēmums, TEBRA

m

Ptot.

Modelled mixing zones of wastewater treatment plants discharges for Ptot., Ntot.

Map of discharge of “Aizputes komunālais uzņēmums” (N400154) and surface

water quality monitoring station “Tebra, 1.5 km lejpus Aizputes”

Distance from discharge to

the closest surface water

quality downstream

monitoring station –

Tebra, 1.5 km lejpus

Aizputes –

1.1 km

→→→→

It means, that even

shortest in frame of

HOTRISK project modelled

mixing zone for total

phosphorus after 1stround sampling results -

3.5 km - are longer than

distance from discharge to

closest surface water

quality downstreammonitoring station

Water body

code, name

Monitoring

point

Provisional

ecological

quality due

to Ntot.,

according

to 1st river

basin

manageme

nt plans

typology

Provisional

ecological

quality due

to Ntot.

according

to reviewed

typology in

frame of

HOTRISK

project

Provisional

ecological

quality due

to Ptot.

according

to 1st river

basin

manageme

nt plans

typology

Provisional

ecological

quality due

to Ptot.

according

to reviewed

typology in

frame of

HOTRISK

project

Provision

al

ecological

quality

due to

N/NH4

according

to 1st

river

basin

managem

ent plans

typology

Provision

al

ecologica

l quality

due to

N/NH4

accordin

g to

reviewed

typology

in frame

of

HOTRISK

project

Year

V018, Tebra Tebra, 1.5 km

lejpus

Aizputes

1.31 1.31 0.151 0.151 0.10 0.10 2009

Tebra, 1,5 km

augšpus

Aizputes

0.89 0.89 0.101 0.101 0.10 0.10 2009

Results of provisional ecological quality due to Ptot., Ntot., N/NH4 according to last state surface water

quality monitoring data in water bodies V018, Tebra

Symbols

Colour

Provisional ecological

quality

High

Good

Moderate

Poor

Bad

Provisional ecological quality for Ptot., Ntot., N/NH4, O2 upstream and downstream selected hot spots,

monitored in the frame of project HOTRISK

Waterbody

type / type for

stream or ditch Ptot. Ntot. N/NH4 O2

Upstream Tukuma ūdens 3 0.078 1.78 0.048 9.6

Downstream Tukuma ūdens 3 0.14 1.9 7.9

Upstream Kuldīgas ūdens 6 0.023 0.68 <0.012 12

Downstream Kuldīgas ūdens 6 0.026 0.62 10.1

Upstream Saldus Komunālserviss 2 0.64 6.8 0.79 8.9

Downstream Saldus

Komunālserviss2

0.69 10.1 9.6

Downstream Saldus

Komunālserviss, grīva, pirms

ietekas Ciecerē

2

0.67 9.9 8.7

Upstream Aizputes komunālais

uzņēmums3

0.06 0.82 0.067 7.84

Downstream Aizputes komunālais

uzņēmums3

0.132 1.5 6.1

Upstream Ventas ciems 6 0.024 0.76 <0.012 11.4

Downstream Ventas ciems 6 0.024 0.65 9.3

Upstream Tukuma piens 3 0.07 2.02 0.044 10.6

Downstream Tukuma piens 3 0.05 1.7 8.1

Upstream Ezeres pagasta pārvalde 5 0.04 1.05 0.102 8.8

Downstream Ezeres pagasta

pārvalde 5 0.06 0.76 6.7

Upstream Novadnieku ciems 2 0.028 0.74 <0.012 11.4

Downstream Novadnieku ciems 6 0.028 0.6 9.5

ConclusionsConclusionsConclusionsConclusions� It is necessary to assess location of surface water quality monitoring stations below cities – if they are

not located in influence of mixing zones of polluting substances. If one of the existing monitoring point

is located within an area of EQS exceedance, - may be to declare that the monitoring point is ‘no longer

representative’ for that (those) substance(s), though it may remain representative for others purposes,

e.g. trends of substances concentrations in rivers. / “Technical guidelines for the identification of mixing

zones”/

� Excel based discharge tool is a good tool to calculate mixing zones for a tier 1-tier 2 assessment. There is

a need to adopt the national criteria for mixing zones:

� Conformity assessment of taking over default criteria from «Guidelines...» [10 x river width with a

maximum of 1 kilometer for AA-EQS and 0.25 * width for MAC];

� Conformity assessment for limiting values to model mixing zones for nutrients – use of limiting

value between good/moderate class is in line with aims of EU Water Framework Directive; is it in

line with best available technologies for phosphorus and nitrogen treatment?

� There is a need for long term, at least 12 times per year statistics of wastewater flow and quality to

find the best time to take wastewater samples to get data for worst case scenario.

ThankThankThankThank youyouyouyou forforforfor attentionattentionattentionattention!!!!

From: Stowa. Natural constructed wetlands between well-treated

waste water and usable surface water. Waterharmonicas in the

Netherlands (1996-2012). Rapport 2013/08.