DE LOS SERVICIOS PERSONALES

oil/water separation is implemented at military installations to comply with the Federal, state and local requirements and to minimize the impacts of oils and greases on the collection system and downstream treatment systems. These considerations are further discussed below.

5.3.1 Regulatory Compliance. Regulations which may require

the use of OWSs are primarily associated with PL-100-4, Water Quality Act of 1987. Discharge of wastewaters to waters of the United States is regulated under 40 CFR Section 402 NPDES permit regulations, 40 CFR Section 403 Oily Wastewater Discharges to Sewers Under General Pretreatment Regulations, and Stormwater Permit Requirements under 40 CFR Section 122.26. These

regulations are enforced by Federal, state, or local regulatory authority. Military services also enforce these regulations for oily waste being discharged to Federally owned treatment works governed under the Federal Facility Compliance Act.

Discharges of oily waste from fuel storage areas must be permitted under the NPDES program. The installation should implement pollution prevention measures and best management practices to minimize or eliminate oily waste contact and discharge from diked areas at the fuel storage area which will eliminate the need for oil/water separation. Spill Prevention Control and Countermeasures Requirements, 40 CFR 112.7, is for emergency spill control actions and should be considered separate from routine operations. However, provisions of the General Pretreatment Regulations applicable to oily waste discharges to sewerage systems are found in Section 403.5(b). These provisions prohibit discharge of the following:

a) Any pollutants which cause interference or pass

through treatment works

b) Pollutants which create a fire or explosive hazard

in the sewerage system

c) Petroleum oil, nonbiodegradable cutting oil, or products of mineral oil srcin, in amounts that will cause

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interference or pass through or exceed effluent discharge limits (some sewer use ordinances also contain specific numerical limits)

d) Pollutants which result in the presence of toxic

gases, vapors, or fumes within the sewerage system that may cause acute worker health and safety problems

In addition to these provisions, many POTW sewer use ordinances prohibit oil and grease discharges that could accumulate in collection system piping and obstruct flow, or that could accumulate in the sludge of treatment works, resulting in hazardous substance disposal requirements.

5.3.2 Related Impacts on Collection/Treatment Systems. In

addition to impacts outlined in regulations, wastewater

containing significant quantities of oil and grease can impact the collection and treatment systems in the following ways:

a) Accumulation of oil and grease in collection

piping, causing obstruction of flow

b) Accumulation in treatment facility sludge,

resulting in hazardous substance disposal requirements For these reasons, wastewater discharges from maintenance facilities and washracks should be managed to prevent adverse effects to the treatment plant and to protect the environment from releases to surface waters.

5.4 Evaluating the Need for Oil/Water Separators.

Numerous oil/water separators (OWSs) exist at military bases, some of which are not needed or are not accomplishing their intended purpose. Misapplications and inadequate performance have resulted from poor design, improper selection of pre- manufactured units, failure to adequately understand the character of wastewaters being treated or pretreated, and lack of proper maintenance. Consequently, the need for an OWS should be carefully evaluated before undertaking its design.

Figure 10 presents a decision diagram for determining whether an OWS is needed at a particular location. In using the decision diagram, the following source control issues should be

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Figure 10

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a) Using detergents to clean up work areas increases

emulsification and inhibits gravity oil/water separation. Use of high-pressure water also causes emulsification but is generally less detrimental to oil/water separation than the use of

detergents.

b) Use of dry absorbents should be considered to

minimize the amount of oils reaching sewers. Dry absorbents may be collected and disposed of with solid waste materials. If possible, wet processes should be replaced with dry processes, and floor drains should be plugged.

c) Implementation of point source controls may

eliminate or reduce the wastewater volume and contaminant concentrations. For example, used oils may be segregated for disposal or reuse rather than allowing them to enter the

wastewater stream. Implementing point source controls may also be more economical than providing a wastewater treatment system. Point source control techniques include process change or

modification, material recovery, material substitution, wastewater segregation, and water reuse/recycling.

d) Consider changing the point of discharge to

negotiate less stringent requirements and to protect sensitive environmental areas. For example, it may be practical to reroute a stormwater permitted outfall to a sanitary indirect discharge when the stormwater flows are low and the permitted stormwater discharge limits are overly restrictive. Extraneous stormwater should be excluded from sanitary systems.

e) The stormwater pollution prevention plan should

implement best management practices which will minimize or eliminate the need for oil water separators in most instances.

f) The formation of oil emulsions should be minimized

and emulsions should be segregated for special treatment whenever possible. Emulsions are usually complex, and bench or pilot plant testing is generally necessary to determine an effective method for emulsion breaking.

g) Current process operating practices should be

investigated to determine if good housekeeping practices are employed and if changes can be made to reduce waste materials or use of excess water. In many cases, proper attention to control of operations can greatly reduce the amount of soluble oil requiring treatment. Minimizing leaks, avoiding spills, using

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drip trays, employing spill containment techniques, and

discarding oil only when it is no longer serviceable should be a part of any oily waste control program. OWSs are not to be used for spill containment.