7000 HARDESON RD 2018-01-02 MF Import

Calculations must be submitted for the compost filtef treatment system and the upstream control structures showing that the developed peak rate of Clow from the 6 month, 24-hour storm will be routed to and treated by the compost filter treatment system. A contingency plan must be submitted to the City for review and approval, defining what constitutes failure of the system and indicating the steps to be taken in the event of system failure. A monitoring plan must also be submitted to the City for review and approval. The goal of the monitoring plan is to document that stormwater runoff from the 6 month, 24-hour storm is flowing through the compost media before discharge to Merrill and Ring Creek. It would appear that flow measurement from each bay of filters is possible. Is it proposed? How often? What flow rates are expected from each bay? In addition, the height of compost media within the cartridges should be measured periodically (if settlement of the media is a possible problem). I also have the following questions, which may or may not be answered by the operations and maintenance manual: Do the radial cartridges come "pre -filled" with compost, or are they filled on site? If they are filled on site, the plans or maintenance manual should specify the procedure to be used. When maintaining the system, are entire cartridges replaced, or is just the compost within the cartridge replaced? If settlement of the compost media in the radial filters is a possible concern, will the cartridges be "topped off" periodically to prevent stormwater flow from passing through the cartridge without being treated by the compost media? Given the configuration of the system, is it possible to determine if an individual cartridge has failed, or just a section of cartridges? What signals the need for replacement of the cartridges? How will sediment that accumulates in the treatment cells be removed?