CCP 05-10-1999 - Laserfiche WebLink

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, e e . CITY OF ARDEN HILLS MEMORANDUM DATE: April 29, 1999 TO: Brian Fritsinger, City Administrator Dwayne Stafford, Public Works Director 1) Sewer Maintenance Machine FROM: SUBJECT: Backl!.round The need for a sewer vacuum machine was identified by the City of Arden Hills when the current Director came on board in 1995, This truck-mounted machine is designed to vacuum sludge and debris from sewer manholes as lines are cleaned, while returning liquids back into the system, Currently, Public Works employees insert a shop-made screen in the downstream manhole while cleaning lines, This screen collects sand and debris that is then removed by hand, Beyond the physical aspects of this type of work, OSHA classifies any entry into a manhole or lift station as a "confined space entry," To legally perform this entry, the following steps must be taken: . Confined space entry permit must be filled out; . Air quality tests must be continuously performed; . Blowers must be provided to circulate fresh air; . An additional "spotter" person must be present while any worker is in a confined space, The vacuum machine eliminates most personnel entries into a confined space area, Other Machine Uses There are currently four (4) grit chamber manholes in place in the City's stormsewer system, These chambers collect the sand and debris washed into the stormsewer, thus reducing the amount that enters our lakes and streams, The need for more grit chambers will likely occur as more streets are reconstructed with curb and gutter and stormsewer, and room for sediment ponds is not available, To this point, the grit chambers have been cleaned with demonstration vacuum equipment. During water main, sewer main and force main repairs, other cities use their vacuum machines to draw the saturated soils away from the area to be repaired, This allows the dry soils to be returned and compacted in the repair excavation, When all the soils are excavated with a backhoe, often the entire excavation is hauled away and replaced with dry, compactable material.