Hinged aluminium lids and light-duty grates are factory-fitted to poly pump station packages for easier installation. Cast iron lids and heavy-duty galvanized grates are installed onsite. Both types of lids must be concreted into an in-situ concrete collar or cast as part of site paving/slab. The collar should sit above the concrete walls to support the lid's load. If the poly chamber is non-load-bearing, the collar or slab must be oversized to rest on virgin soil. In cases of expected soil movement, in-situ concrete walls or pillars may be required. The chamber should be set an extra 200mm into the ground. For high water table conditions, the chamber may need anchoring with a ballast block, an extended toe, or encasing in concrete. Stabilised sand can be used as an alternative backfill. Consult civil engineers on each project to confirm site requirements before installation.