65. In order to monitor the quality of the groundwater migrating into the soil where the disposal areas, a leachate or water treatment system or a stockpiling platform for contaminated soil or other residual materials intended to be used as cover material is sited, the operator must install 1 or more networks of observation wells in accordance with the following provisions.
If the leachate or water treatment system is situated in whole or in part within 150 m of the disposal areas, a single network of observation wells is required, otherwise the disposal areas and the location of the treatment system and the stockpiling platform, if applicable, must each have its own network.
The number of wells in a network of observation wells depends on the surface area occupied by the disposal areas, the treatment system and the stockpiling platform, if applicable. The location of the wells and the number of sampling points required depends on the hydrogeological conditions of the sites, subject to the following:
(1) no observation well is to be situated beyond the outside perimeter of a buffer zone established pursuant to section 18;
(2) the observation wells must be situated at a maximum distance of 150 m hydraulically downgradient from the disposal areas or the location of the treatment system or stockpiling platform, if applicable, so that the quality of the groundwater reaching that distance can be monitored. If all or part of a buffer zone has been established on an existing landfill, the monitoring perimeter may be extended to include the landfill, but without exceeding the distance of 150 m from the disposal areas or related treatment system or stockpiling platform;
(3) a network of observation wells must consist of at least 3 wells for the first 8 ha of land and 1 well for each additional 8-ha portion of land or remaining portion of less than 8 ha;
(4) at least 1 additional observation well to monitor the quality of groundwater before its migration into the soil where the disposal areas, treatment system or stockpiling platform, where applicable, is situated must be installed hydraulically upgradient, or if the hydraulic upgrade cannot be determined because of hydrogeological conditions, at any other location making it possible to ascertain the quality of the groundwater representative of the groundwater migrating into the monitoring perimeter established under this section.
For the purposes of this section, a pond, basin or reservoir, except surface water sediment basins, in which water accumulates that does not comply with the limit values set out in section 53 is considered to form an integral part of the water treatment system.
O.C. 451-2005, s. 65; O.C. 451-2011, s. 16; O.C. 868-2020, s. 2111.