nationaal congres bodemenergie effecten van bodemenergie op grondwaterkwaliteit
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Nationaal Congres Bodemenergie Effecten Van Bodemenergie Op GrondwaterkwaliteitTRANSCRIPT
1Watercycle Research Institute
2Watercycle Research Institute
Research questions and approach
Questions:- What are the risks of ATES systems on groundwater quality (chemical, microbiological and physical)?- Where can we allow what type of ATES systems?
Approach/this presentation:- Field: Monitoring ATES systems at 3 sites (mostly 7-17°C)- Lab: column experiments (5-60°C)(Numerical modelling with Seawat,Phreeqc: next step)
3Watercycle Research Institute
Field site – ATES system Eindhoven
Monitoring program 2005-2012 (Brabant Water)- What effects are visible at field scale?- What is the consequence for drinking water production?
4Watercycle Research Institute
Site description
ATES site
Drinking water Pumping station
- Coarse and heterogeneous aquifer
- High groundwater flow velocity (>25 m/year)
5Watercycle Research Institute
Field data – EindhovenAmbient groundwater quality: depth profiles
-ATES system is realized in Sterksel aquifer
-Vertical redox zonation: removal of NO3, SO4; followed by appearance of CH4
6Watercycle Research Institute
Field data Eindhoven: Water quality patterns in ATES wells
Ambient concentration range
Data shows: -Mixing of shallow Cl and SO4
enriched (anthropogenically influenced) and deep groundwaterCycling of redox zones (Fe, NO3, NH4) consequences in aquifer?
7Watercycle Research Institute
Initial situation:
Vertical stratified aquifer:shallow groundwater enriched in SO4
deep groundwater depleted in SO4
Mixing effect explained by a simple model simulation
8Watercycle Research Institute
End of next ATES season:
Injection in other ATES well. Bel drifted further
Initial situation:
Vertical stratified aquifer:shallow Cl/SO4 enricheddeep depleted
Start with ATES:
Extraction of shallow enriched SO4 water anddeep depleted water, mixing and reinjection
Mixing effect explained by a simple model simulation
9Watercycle Research Institute
End with season 1:
Part of injected bubble has drifted off.
Mixing effect explained by a simple model simulation
10Watercycle Research Institute
End of next ATES season:
Injection in other ATES well. Bel drifted further
Initial situation:
Vertical stratified aquifer:shallow Cl/SO4 enricheddeep depleted
Start with ATES:
Extraction of shallow enriched SO4 water anddeep depleted water, mixing and reinjection
End with season 1:
Part of injected bubble has drifted off.
End of storage season:
Injected bubble has away from ATES well.
Start of next ATES season:
Injection in other ATES well.
Mixing effect explained by a simple model simulation
11Watercycle Research Institute
Field data: microbiological observations
3x1034354.0x103454121.3Colony count 37°C (CFU/mL)
8.4x1032.4x1031.1x1041.6x1038.1x103195 Colony count 22°C (CFU/mL)
maxμmaxμmaxμ
29172919100Sulphite reducing clostridia
294296130Enterococci
2912921180E. coli
nPosnPosnPos
ATES well W10 ATES well W9 Ambient Groundwater
Parameter
- Increased elevated colony counts at 37°C - Higher prevalence of SSRC may indicate a faecal contamination - Cause unclear: drilling?, leakage along borehole?, sampling?- No likely risk however for PSWF due to subsurface residence time (>>100days)
12Watercycle Research Institute
Conclusions from field data
No chemical drinking water standards are exceeded. Biological standards were exceeded, but forms no likely risk for the PSWF.
Observed water quality impacts by the Eindhoven ATES system are explained by mixing/homogenisation of ambient vertical quality differences.
General conclusion (or hypothesis): mixing waters by ATES and potential microbiological contamination increases vulnerability of nearby pumping stations.
13Watercycle Research Institute
Laboratory investigations
Aim: - Detailed analyses of hydrochemical changes due to changing temperature
- Investigate more extreme temp.
14Watercycle Research Institute
Collection of soil cores
15Watercycle Research Institute
Sampling of influent water
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Installation in lab
Pumps
Circulation Coolers (5 and 12°C)
Cores
Control Unit(heatinglogging ofpH,DO &EC)
17Watercycle Research Institute
Selected results lab experiments: effluent curveswith 1 day residence time
Results @ 5 °C:Carbonate minerals dissolution(HCO3)
Results @ 25 °C: Desorption of trace elements (As)
Results @ 60 °C- precipitation of siderite-calcitesolid solutions (not pure calcite!)
- Desorption of cations (K, Li, Si) and trace elements (e.g. As)
18Watercycle Research Institute
Conclusions from column testing
- Lab studies show some effects at low T: carbonate dissolution (5°C) & desorption of trace elements (25°C).
- But most effect at 60°C: desorption of cations, precipitation of Fe-Mn carbonates and respiration of organic carbon
19Watercycle Research Institute
Questions?