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Know where your wastewater goes -
does the drain lead to a sanitary sewer and a treatment facility, or does the water flow
directly to a nearby creek or river? In either case, you want to reduce pollutants, but if
you are sending wastewater directly to a river, stream, or lake, you will want to take
extra precautions. |
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Check with your local waste water
treatment operator to determine any restrictions or permit requirements for wastewater
discharge. Some districts prohibit certain types of wastewater from being discharged to
the sanitary sewer system. If your wastewater flows directly into a river or stream, you
may be required to obtain a permit. |
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Plant carefully in the area in
which vehicles are washed. Any impervious surface like concrete or asphalt used for
washing cars should be wide enough to avoid accidental spraying of other equipment.
Drainage surfaces should be graded in a way to direct wash water appropriately. Keep water
away from shop repair areas or chemical storage. |
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Whenever possible, wash vehicles
on a grassy area that absorbs and naturally filters wastewater. Businesses that wash only
a small number of vehicles might design a swale - a grass lined ditch - to catch and
filter wastewater. |
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Keep cleaning solutions to a
minimum. The smaller the amount of detergents, brighteners, and other materials used, the
less impact on water quality and the greater cost savings. Look for the least hazardous
products and use biodegradable substances whenever possible. |
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Before discharging any wash water
to a sanitary sewer, remove as many pollutants as possible
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Use a grit trap or a detention
tank to catch solids.
A coalescing-type oil/water separator or similar unit will catch oil. |
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Keep wash water that contains
soaps, detergents, hot water, steam, or other chemicals out of the storm drains. There are
several ways to do this:
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Wash vehicles on a grass-covered
surface when possible.
Install a sump or a grit trap to collect and filter the wastewater.
Collect wash water with a portable vacuum recovery unit.
If the water drains to a catch basin, make sure that the outlet to the storm drain
is closed during washing. |
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Install catch basins with
sediment traps and create an inverted elbow outlet to trap floating oils. Clean catch
basins when they are 30% full with solids - at least once a year. Make sure oil and solids
are disposed of properly. |
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Reduce the amount of paint chips
and heavy metals removed from vehicles during the washing process. This might require
changing the cleaning agent or reducing water pressure. Paint and metals should be kept
out of the sewers. |
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If your washing takes place on
painted or metal surfaces, don't use abrasive detergents. These washing agents will draw
pollutants from the surfaces into the wash water. |
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Use detergents that are
phosphate-free and break down easily in water. |
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Cleaning operations that use
metal brighteners, caustics, acids, halogenated hydrocarbons or solvents should apply
various methods to trap and hold water before it reaches the sewers. These include:
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An oil/water separator to remove
floating oil; |
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An air stripper to remove
volatile organics; |
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A sand filtration unit to remove
dissolved solids and metals; |
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A carbon column to remove
organics and metals; and |
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A reverse osmosis unit to remove
metals. |
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If your business discharges
wastewater to a sanitary sewer district, be sure to contact your local sewer authority.
Each local sewage treatment provider sets standards for pretreatment. Your local agency
can advise you on ways to save money and reduce water pollution. |
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The best way to prevent pollution
and save money on water use and sewer fees is to recycle wash water. Such systems require
up-front investment but should result in cost-savings over time from lowered water and
sewer bills. |