7000 HARDESON RD 2018-01-02 MF Import

JUL 24'96 17:00 FR U & H PACIFIC 206 822 5341 TO 12062598829 P.05/09 W. Michael Crowson, P.E. June 11, 1996 Page Throe in orifice How. First you must insure that there ate no backwater influences causing the outlet to be in outlet control. It should be relatively easy to periodically check the level of the media in the cartridge. However, we have had units tested for a number of months and seen no significant settling. If you do pe fomt then observations we would greatly appreciate your feedback for our information and reference_ The radial flow filters come charged with filter media. Refilling is addressed in the O&M When the system is maintained the cartridges are removed and the filter media is replaced. If CSFTS is providing the maintenance, the cartridges will be replace with new ones with fresh compost. If maintained by others, they can remove and replace the compost in the same cartridges. We have not seen settlement of the compost media, however the cartridges are inspected after installation to insure they are lull. If they we not, additional media is added at that time. Given the configuration of the system it is difficult to tell if an individual cartridge has failed - However, the system tends to be self-correcting. For example, if a cartridge receives a heavier sediment loading than the others, it will pass less water and trap less sediment. This allows the others to "catch up." We are estimating that the cartridges need to be recharged once every two to three years. This is to insurc that, given' nw l circumstances there is no significant level of pollutants that would trigger any levels of classification as a dangcmus or harandou s waste. If backwashing of the filter does not mestore the permeability or the filter m tdia disassociates, it should then be replaced. The O&M manual will provide much higher level of detail. As we gain more field experience the maintenance processes and procedure will be refined and available to filter owners. Sediment from the treatment cells should be removed using a vector truck or by hand whichever the maintenance organimtion finds most economic. The sediment should be disposed in the same manor as sediments removed from other storm water treatment facilities. 07/24/96 16:52 TX/RX NG.0327 P.005 M