Slide 37 of 52
Notes:
Materials deposited on the surface of the filter chamber (e.g., trash and litter) should be removed manually. Grass clippings and other organic debris from landscape areas on the catchment should be bagged and removed from the site to prevent them from washing into and contaminating the sediment and filter chambers. Vegetation growing within the basin should not exceed 18" in height.
Removal of silt from filter bed should be conducted when accumulation exceeds approximately one-half (1/2) inch. When the filter layer will no longer draw down within the design period, the top layer of sand or organic media, sacrificial failure zone, or ballast gravel must be removed and replaced with new materials conforming to the original specifications. Any discolored or contaminated material below the surface shall also be removed and replaced. Removed material should be replaced with fresh sand or organic media meeting the original design specifications. The contaminated material should be dewatered and disposed of at a pre-approved and permitted location.
Urban hotspot land uses, particularly automotive uses with heavy oil/grease loadings, will require semi-annual clean-out of the sedimentation chamber and more frequent inspection of the filter bed.
Access manholes, gate valves, flumes and other facilities shall be kept clean and ready for use.