Containment & Filtration Solutions

Oil Water Separator Maintenance

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Courtesy of Courtesy of Containment & Filtration Solutions

Oil water separators (OWS) can be co$tly to maintain, $20,000 or more on average per cleaning and if not properly managed, can be very expensive conduits of pollution. Have you taken steps to minimize the effects and consequences on your operating co$t?

  1. When was your facility’s last OWS maintenance performed?
  2. Is your employee’s attitude, don’t worry we have an Oil Water Separator?
  3. What is your company’s last local, state, or EPA inspection?

A typical maintenance schedule for an OWS properly sized and maintained with moderate to light loads should be quarterly,

YES quarterly!

Example, light-solids of 75ppm in a flow of 100 gpm flow will produce 20 cubic feet of sludge a week!

Not many Oil Water Separators can handle that amount of sludge without becoming impaired or even worse completely none effective, passing the oil straight through the system into your outflow. The effectiveness and/or removal rates can be significantly reduced or all together stopped. Most Oil Water Separators have detection for high oil/hydrocarbon collection, but provide no warning if the collection/treatment process is not happening.

Just because the system is not backed up, doesn’t mean it is still working. Ultimately the time between maintenance/cleanings is directly related to the separator’s ability to handle solids and oil while maintaining function, and for a majority of facilities, this is 3-4 times a year. Function is the key.

To effectively discuss FUNCTION, we need to go over the fundamentals of how an Oil Water Separator works. Without getting into too much detail, an OWS removes or reduces the amount hydrocarbons in a given flow. This separation is accomplished by using what the industry refers to as coalescer filters. A coalescer filter is a technological device performing coalescence/coagulation (the process by which two or more droplets, bubbles or particles merge during contact to form a single larger droplet, bubble or particle).

The process of coalescence cannot happen properly or at all when the solids, oil and sludge overwhelm the coalescer filters. When sludge builds up, flow in those areas is reduced and redirected within the coalescer, causing an increase in the velocity above design limits, impeding or stopping the particles from coalescing or coagulating into larger droplets/bubbles/particles. In some cases this flow can even reintroducing particles already removed increasing the level of suspended pollution within the system. This in turn keeps the stormwater in an emulsified state not allowing oil/hydrocarbons to float to the surface and/or the Total Suspended Solids (TSS)/solids from sinking to the bottom. Therefore, this sludge fouling the coalescer filters can lead to significantly decreased removal capabilities, too much equals not at all! If oil is staying emulsified/suspension then the outcome will simply be the contamination will remain within the stormwater and the Oil Water Separator becomes a very expensive conduit for the pollution to continue into a local stream, river, or lake.

The scariest part is this is a silent failure that can go undetected by all except the Local, State or EPA Officer who is performing a random outfall test just behind your facility.

  1. “What?” Load is the pollution. (TSS, Oil, Sediment, etc.)
  2. “Why” Load is made by the action performed within a given area.
  3. “How?” Load is introduced into a system via a stormwater inlet/drain/basin.
  4. “Effect?” Load controls the effectiveness of removal rate with in the OWS.

To reduce this co$t and exposure is simple, reduce and/or control the load going into the system. The answer is Drain Guardian™ platform; a simple stainless steel insert placed below the grate and within the basin will reduce the load by a multi staged filtration process and/or in the event of a larger loss/spill give the user the ability of absolute containment flow above the OWS system. These units can be cleaned and maintained with your personnel not co$tly contractor$. This practice of cleaning with your onsite personal is twofold; bringing awareness to the employees of losses and by helping identify practices which contribute the load within individual stormwater basin’s watershed that would otherwise go undetected.


Eliminate Load: Don’t rely on the Oil Water Separator to handle (fuel, coolant, solvent, oil, or paint) events/spills/losses by washing them into stormwater inlets. Instead, capture and/or reclaim these events/spills/losses when and where they occur. The further upstream an event is captured, the lower the co$t of dealing with it as well as increasing the effectiveness of capture!

Minimize Load: Minimize the amount of solids and oils that enter your facility’s stormwater system by tracking and analyzing the load captured with in the inserts at each basin and identifying the practice which supplied the contamination. This processes is the most important, by involving the employees in a given area the awareness will make all the difference in the reduction. The less solids and oils that reach the OWS, the less frequently sludge and floating oil must be removed from the OWS and the better it will works.

Set-up a Maintenance Schedule: This is a contracted task and will involve significant co$t, A field service crew with a Vacuum Truck can perform this service by pumping the sludge and oil then pressure washing from the surface. Bottom line this work is contracted out and is highly specialized and is reflected in the co$t, so the longer the interval between cleanings the more your facility budget will reflect the savings. By utilizing Drain Guardian™ with an OWS system, maintenance intervals have been shown to be reduced by half as much as those without. Clearly showing the cost associated with using the Drain Guardian is quickly recovered.

By understanding; “What, Why, How, & Effect” load plays on your Oil Water Separator can and will help by saving your facility in cutting overall co$t, and by bring awareness and focus on the day to day practices within your facility.

Safety and the Bottom Line (cost) can be related and share the rewards by the implementation of the right practices and equipment.

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