Recharge systems for protecting and enhancing groundwate

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TOPIC 1
Recharge systems / Alternative recharge systems
Early 2004, after checking all distances, the infiltration pond was locally recalibrated to increase the distance with
the nearest wells.
Table 2. Repartition of distance between wells and infiltration pond
Distance
< 40 m
40 – 49 m
50 – 59 m
60 – 69 m
70 – 79 m
80 – 89 m
> 90 m
Number of wells
10
44
23
17
3
2
13
The surface area of the infiltration pond is 18,200 m 2 ; the infiltration capacity is 2,500,000 m 3 /year. Yearly
3,500,000 m 3 /year should be extracted, or 1,4 the infiltration rate, to ensure that the infiltration water is totally
recaptured. The groundwater is treated with the existing plant: aeration and rapid sand filtration.
Monitoring wells were installed; three are controlled online, as is the level in the infiltration pond.
Results of artificial recharge
Infiltration started the 8 th of July, 2002 and apart from half September until half December 2002, and 10 days at the
end of January 2004, Torreele produced normally (Fig. 3). The salinity of the water extracted out of the infiltration
area gradually decreased, from 800 µS/cm before infiltration started to around 400 µS/cm (Fig. 3). When half
May 2004, UF filtrate no longer was used for the infiltration water, salinity declined again. Now the salinity stabilized
around 300 µS/cm.
Figure 3. Production of infiltration water and evolution of salinity (left)
Monitoring between the infiltration pond and the extraction wells showed that:
• near the infiltration pond there is a great vertical flow to the lower layers; this flow reduced significantly with
depth and was locally hindered by clayey sediments;
• more distant from the infiltration pond, the vertical flow reduced and the water flowed mainly horizontally
through the aquifer;
ISMAR 2005 ■ AQUIFER RECHARGE ■ 5th International Symposium ■ 10 –16 June 2005, Berlin