How frequently does HRC need to be applied?
The frequency that HRC needs to be applied varies from site-to-site and is dependent on the site’s application strategy and goals. There are two treatment approaches, grid- and barrier-based, used for HRC projects. A grid-based application pattern can be used to treat a specified area while a barrier-based approach can be used to stop plume migration or treat a lengthy (> 500 feet) plume. The grid-based approach is typically used to treat the zones of higher concentrations and is intended to be a single application. Barrier-based applications are often used to cut-off plume migration when a source is still present on the subject site. Therefore the frequency of application will be dictated by the presence of the source. If the source is not removed groundwater will continue to be impacted and in most cases the barriers will need to be recharged every 12-18 months.
