Avoid shaking or aerating the sample to prevent low readings. A duplicate should be dipped and tested for confirmation. D. Test results shall be reported to DEQ no later than September 15. Complete backdrainage of the force main into the wetwell between pump cycles. This requires an ascending main.
Drainage is controlled through a pneumatic pinch or electric plug valve.
Solenoid valves do not last in this type of service. Compressed air injection. The design should include control instrumentation and an airflow meter. Air can also be injected into wetwells to freshen the sewage and extend the aerobic zone of the force main. Ferrous chloride is being used in one force main which discharges directly to an open plant headworks.