Check whether the outlet is clogged Y__ Check whether the underdrain Standing water is present after 1 pipes are clogged or damaged the design drain time N__ Ventilate the underdrain pipes Work Order# _________ Check whether the filter fabric Sand or pea gravel present in the Y__ around the pipe is broken and 2 discharge pipe or outfall of the repair if necessary sand filter N__ B2 Work Order# __________ Underdrain Check whether the seasonal high water table is above the bottom of the sand filter Continuous discharge of water Y__ from the outfall when it has not 3 A retrofit may be required if the rained within the past 72 hours N__ system is intercepting and the bed is completely dry groundwater Work Order# __________ Note:
B2 Underdrain 1 Standing water is present after the design drain time Y__ N__ Check whether the outlet is clogged Check whether the underdrain pipes are clogged or damaged Ventilate the underdrain pipes Work Order# _________ 2 Sand or pea gravel present in the discharge pipe or outfall of the sand filter Y__ N__ Check whether the filter fabric around the pipe is broken and repair if necessary Work Order# __________ 3 Continuous discharge of water from the outfall when it has not rained within the past 72 hours and the bed is completely dry Y__ N__ Check whether the seasonal high water table is above the bottom of the sand filter A retrofit may be required if the system is intercepting groundwater Work Order# __________ Note:
05-surface-sand-filter-underdrain-main-field-manual-april-2015.docx