La gestion intégrée des eaux pluviales - AQUA-ADD Interreg IVC ...

10
Long-term
projects
ECOLOGICAL MONITORING
AND MAINTENANCE
OF THE “RAINWATER”
HERITAGE
The Contal mixed development zone
La-Tour-de-Salvagny
Ecological monitoring of the lakes and wetland zones
In addition to monitoring the operation of works, full
ecological reviews are carried out regularly from the time
such works come into service.
These reviews cover the species of plants and animals
(essentially fish and amphibians) and the physico-chemical
quality of the water and sediments. By carrying out these
monitoring operations, it has been possible to modify
the servicing practices for the works to maintain
the balance of fauna and flora.
These results are shared with the local environmental
associations which bring them to the public’s attention,
in particular by means of educational panels.
The ecological development of the lakes is regarded
as remarkable by all the fauna and flora conservation
associations. All the local stakeholders are today working
to conserve the biodiversity of the site.
Monitoring of the water table downstream from
Grand Lyon’s percolation works
The renewal and the quality of the water table are analysed
regularly. Checks on the wastewater before percolation are
also carried out:
> On the wastewater (4 times per year): analysis
of the parameters DB05, COD, KN and hydrocarbons;
> On the ground water (4 times per year): analysis
of the parameters of conductivity, TOC, KN, nitrates,
hydrocarbons, pesticides containing nitrogen (former
agricultural zone) and heavy metals.
The ground in the percolation zone can also be charged
with pollutants due to its role as a filter during the percolation
of water. During maintenance interventions, soil samples
from a depth of 50 cm are taken and analyses then allow
the quantity of heavy metals, chlorinated solvents,
hydrocarbons and the pH and TOC (detection of carbon
pollution) to be measured.
OTHU: better understanding for better management
The Urban Hydrology Land Observatory (Observatoire
de Terrain en Hydrologie Urbaine - OTHU) is an off-site
laboratory which studies urban waste and its impact
on the receiving environments in particular in periods
of heavy rain. Its role is to propose new sewerage design
and management solutions in order to respond to the challenges
facing Grand Lyon. A partner of the OTHU, Grand Lyon makes
its wastewater and rainwater works available as a study
and research site. The results are then shared and used
in the public water policy.