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HWTR Pollution Prevention

My Watershed

Pollution Prevention Checklist for Metal Fabrication and Machining Departments

Photo: man welding metal.

The Washington Department of Ecology encourages schools and laboratories to find safer alternatives to reduce, or even eliminate the use of toxic substances.

The table below lists common hazardous substances found in metal fabrication and machining departments and preferred alternatives (in bold font), if available. Best management practices that can be used to reduce and prevent toxic wastes are also included.

Throughout all departments there are common issues with proper management of dangerous waste that is generated on site.  The following bullets identify the most common issues and give best management practices (BMPs) for proper identification, accumulation, and disposal of dangerous wastes.

More resources are listed at the bottom of this page.

Download a printable checklist in Word, or pdf.

For more information contact your local Ecology Regional Office.

Items or Processes of Concern Toxic Metal Dangerous Waste Preferred Alternatives
Metal-working fluid X


  • Use non-chlorinated metal-working fluids.
  • Use sulfur-free metal-working fluids.
  • Use dry machining.
  • Monitor and log metal-working fluid concentration, odor, turbidity, refractive index, alkalinity, conductivity, emulsion stability, or pH to avoid excess concentrate and biological growth.
  • Keep pH above 8.5.
  • Periodically clean and disinfect metal-working fluid sumps and trenches.
  • Consider tramp oil skimmers to keep metal-working fluid aerated and free of biological organisms.
  • Use pumps, spigots, and funnels to transfer metal-working fluids.
  • Use distilled or de-ionized water to keep the concentration of dissolved minerals low in metal-working fluids.
Welding X X
  • Use lead-free solders.
  • Use cadmium-free filler metals when fluxing.
  • Use alternative fluxes to reduce volatile organic compound emissions or avoid post cleaning.
  • Optimize flux delivery.
  • Optimize heating of filler metal.
Metal scraps

  • Filter chips to prevent contamination of the metal-working fluid.
  • Drain chips of metal-working fluid before disposal.
  • Store chips and scrap metal under cover.
  • Recycle chips and scrap metal.
  • If chips and scrap metal are not recycled, manage as dangerous waste.
Cleaning solvents   X
  • Use non-chlorinated solvents and thinners.
  • Use methyl alcohol (methanol) for paint stripping.
  • Use a spray bottle or plunger can to deliver solvents where they are needed.
  • Segregate solvent wastes, distill, reuse, or dispose of as dangerous waste.
  • Use solvents until they lose their effectiveness as opposed to when they look dirty.
  • Extend solvent life by filtering solids.


  • Use low or no-solvent adhesives, such as hot melt, heat seal, aqueous-based, or polyvinyl alcohol adhesives.
  • Evaluate your gluing operations to determine if too much is being mixed.
Floor cleaning X


  • Use biodegradable or water-based floor cleaning detergents with a pH of 6.0 to 10.5 at point of use.
  • Avoid the use of detergents with emulsifying agents that reduce the effectiveness of the oil/water separator.
  • Avoid the use of detergents that could cause waste cleaning water to designate as dangerous waste, (e.g., detergents with halogenated or aromatic compounds).
  • Use absorbent pads or trays to catch leaks or clean up spills to prevent waste from going down the drain.
  • Use oil/water separators to prevent oily wastes from being discharged down the drain.
  • Request approval from the local waste water treatment facility before discharging waste water down the drain.
Parts washer X X
  • Use an aqueous parts cleaner. See Automotive and Equipment Repair Departments.
  • Use non-halogenated organic solvent.
  • Recycle spent solvent cleaner.
  • Operate solvent sinks properly, use drip trays, and allow more drainage time.
  • Contract with a service company to maintain solvent sink.
Shop towels or wipes   X
  • Use cloth towels that can be laundered and reused.
  • Keep used wipes and towels in closed containers and label appropriately.
  • Reduce the size of the towel or wipe to reduce the amount of solvent used at the same time.
  • Reuse shop towels or wipes for repetitive tasks.
  • Don't dip towels or wipes in open solvent containers.
  • Limit the amount of solvent available for use each day.
  • Towels that are not laundered should be managed as the material they were used to absorb.
General inventory    
  • Use Environmentally preferable purchasing.
  • Review Material Safety Data Sheets (MSDSs) for hazardous substance information.
  • Properly store hazardous substances.
  • Review curriculum for potential hazardous substance reductions.
All generated waste streams

Spilled products

Unused and expired products
  • Use chemical inventory and tracking software to centralize product ordering, improve product tracking, storage requirement, waste management, reduce disposal of expired product, and minimize duplicate orders to prevent unnecessary disposal.
  • Identify all potential waste streams and establish designation procedures to determine if a hazardous waste or non-hazardous waste.
  • Implement dangerous waste designation, collection, accumulation, and disposal procedures for all waste streams.
  • See Common Dangerous Waste Compliance Issues.

Fluorescent lamps

Mercury-containing equipment
  • Use rechargeable batteries.
  • Use LED lamps when appropriate.
  • Use low-mercury fluorescent lamps.
  • Remove and/or replace mercury-containing equipment and manage as Universal Waste.
  • Implement a battery collection program and manage as Universal Waste.
  • Implement a whole-lamp recycling program and manage as Universal Waste.
  • If not recycled as Universal Waste collect, manage, and dispose of as dangerous waste.

Electronic equipment

  • Use energy-efficient computer and electronic equipment, and appliances.
  • Use vendor take-back programs.
  • Surplus old equipment
  • Recycle as Universal Waste.


This page last updated September 2015