Above
Grade Solutions eliminate confined space procedures
According
to the U.S. Dept. of Labor, many workplaces contain
spaces considered "confined" because their
configurations hinder the activities of employees who
must enter, work in, and exit them. A confined space has
limited or restricted means for
entry
or exit, and
it is not designed for continuous employee
occupancy. Confined spaces include, but are not limited
to underground vaults, tanks, storage bins, such as
those used in wastewater pumping applications.
OSHA uses the
term "permit-required
confined space," to describe a confined space that has one or
more of the following characteristics: contains or has the
potential to contain a hazardous atmosphere; contains a material
that has the potential to engulf an entrant; has walls that
converge inward or floors that slope downward and taper into a
smaller area which could trap or asphyxiate an entrant; or
contains any other recognized safety or health hazard, such as
unguarded machinery, exposed live wires, or heat stress.
The greatest danger facing the person entering a confined space
is a lack of oxygen. Several breaths of an atmosphere holding
less than 6 percent oxygen can disable in seconds and can kill
in minutes. Either the
volume percent of oxygen can be too
little (less than 19.5) or other gases (such as carbon monoxide)
in the confined space may interfere with the body's uptake of an
otherwise sufficient supply. Oxygen deficiency can also
debilitate sensors: Thus, a space with very low oxygen levels
can't be tested for combustible gases since standard instruments
for this purpose require oxygen to function. (The sensor
actually attempts to ignite a sample of the atmosphere and can't
do so when the fuel/oxygen ratio is too high.)
Not only is it dangerous to operate in a confined space, but
it is also costly and time consuming for municipalities to
maintain according to Metropolitan Industries Service Manager
Mike Schiazzano. He says a
permitted confined space needs a minimum three-man crew with the
following safety gear; two multi function gas monitors, tripod
with safety retrieval line, safety harness, a fresh air blower,
a fresh air tank with airline, respirator and escape pack.
Training the crew to use all safety gear along with the
retrieval equipment procedures is also an added requirement. He
adds by eliminating the need to enter or work in a confined
space a municipality can save time and money.
Solutions to Confined Space Applications
Above-grade applications eliminate the danger, costs and
manpower issues associated with confined space applications.
Installations typically consist of a small control and generator
building installed next to wells below grade containing pumps.
The pumps are easily accessible and can be easily removed and
installed without entering well using guide rails.
Costs and labor to maintain such an installation are minimal.
Given that it is above grade and anything below grade is
accessible from above, typically one person can operate the
entire station reducing operating costs. Also further reducing
cost is the elimination of the equipment and safety apparatuses
associated with confined space entry.
Metropolitan Industries, Inc. specializes in the design and
manufacture of above grade, lift station/control packages and
recently completed two such jobs in Merrillville, Ind. that
eliminated previous confined space applications.
Broadfield Lift Station
Working with Robinson Engineering and Contractor Hasse
Construction, Metropolitan Industries, Inc. supplied a triplex,
component lift station complete with a prefabricated building
that houses the controls, valves and generator.
The triplex concrete lift station uses three, 50 HP, rated
for a total 1442 gallons per minute (GPM) at 89.2 feet of total
dynamic head (TDH). One submersible level transducer and four
level switches control on, off, override and alarm levels in
side the basin. Access hatches, a pump removal lift out system
and guide rails allow easy access to pumps for maintenance
without having to enter the 32’ basin.
To eliminate confined space entry, all controls, valves and a back
up generator were housed in a prefabricated building measuring
19’ 3’’ long by 13’ 6’’ wide by 11’ tall building. The building
itself was divided into two sections, one side for the controls
and valves and the other side dedicated to just the generator.
On the control/valve side of the building, a triplex control
panel with programmable logic controller and touch screen
operator interface controls the system. The discharge pipe and
valve assembly are located above grade inside the building for
easy access.
The generator side of the building houses a Caterpillar 125kW,
3-Phase natural gas generator complete with accessories. A 400
amp automatic transfer switch allows for transfer to the
generator during power outages.
Other features of the building include an HVAC system for
climate control, high water alarm with dialer and battery back
up, lighting and smoke detectors.
John Wood School Lift Station
The John Wood School Lift Station is another example of an
above-ground application that eliminates confined space
applications. This application called for a duplex component
lift station again with a prefabricated control, valve and
generator building. The duplex concrete lift station uses
two 40HP submersible pumps, rated for a total 700 GPM at 113’
TDH. One submersible level transducer and four level switches
control on, off, override and alarm levels in side the basin.
Two lift-out hydraulic sealing flange assemblies allow pump
removal for maintenance and repair without entering the sump.
Just as the last example, all controls, valves and a back up
generator were housed in a prefabricated building but this one
measured 18’ long by 13’ 6’’ wide by 9’ tall. The building as
well was divided into two sections, one side for the variable
speed controls and valves and the other side dedicated to just
the natural gas Caterpillar generator inside.
Other feature of the building include an HVAC system for
climate control, high water alarm with dialer and battery back
up, lighting and smoke detectors.
Conclusion
Above grade applications eliminate the dangers and costs
associated with confined space procedures. Towns and villages
save money by eliminating the special safety gear and reducing
the personnel required by OSHA on a service call. Municipalities
will save time by eliminating the requirement of obtaining a
“confined space permit” that designates what is to be done, when
and by whom. No longer will the local fire and police
departments need to be involved as sometimes the permits
dictate. As demonstrated a “permitted confined space” requires
special handling, equipment and a fair amount of extra time and
work if all the rules are followed. Eliminate these hurdles with
an above grade application.
