CWA - Guidelines and Standards
Direct dischargers (an OCS operator, for example) must comply with the effluent
limitations guidelines and the new source performance standards in the NPDES permits;
indirect dischargers must comply with the pretreatment standards.
Technology Based Effluent Limitations Guidelines
Existing point source dischargers (exploratory wells and grandfathered development and
production facilities) are regulated using technology based effluent limitations
guidelines (ELG). Regulated wastes include drilling fluids and cuttings, produced
water, sanitary wastes, and deck drainage among others. Three broad categories of
pollutants are identified in the guidelines: conventional, toxic, and non-conventional.
The level of required discharge control is dependent on the category of the
pollutant.
Conventional Pollutants
The EPA specified the following five pollutants as conventional: biological oxygen
demanding pollutants (BOD), total suspended solids, pH, fecal coliform, oil, and grease.
These pollutants are regulated by the best conventional pollutant control
technology (BCT) standards.
Toxic and Non-conventional Pollutants
EPA developed a list of six toxic chemicals, known as priority pollutants:
Aldrin/Dieldrin, DDT, Endrin, Toxaphene, Benzidine, and Polychlorinated Biphenyls (PCBs).
At present, only PCBs might be associated with OCS operations if a vessel or
platform had transformers that used PCB oils as a coolant. A non-conventional
pollutant is anything not included in the other two categories that still may pose a
threat (ex. thermal pollution). Toxic and non-conventional pollutants are regulated
using the best available technology economically achievable (BAT), a stricter standard
than BCT.
New Source Performance Standards
New point sources and existing point sources of pollutants have different NPDES
regulations. New sources are subject to more rigorous effluent limits than existing
sources based on the idea that it is cheaper to minimize effluent pollutants if
environmental controls are considered during plant design than if an existing facility is
retrofitted. New source discharges must comply with standards based on the
performance of demonstrated technology with the greatest degree of effluent reduction.
These new source performance standards (NSPS) should represent the most stringent
numerical values attainable. NSPS are based upon the best available demonstrated
control technology (BADCT) and are at least as stringent as BAT.
NPDES guidelines define a new source as any area in which significant site preparation
work is done. EPA interprets “significant site preparation” for offshore
effluent guidelines as “the process of clearing and preparing an area of the ocean
floor for purposes of constructing or placing a development or production facility on or
over the site.” Thus, development and production facilities at a new site would
be new sources. Development and production facilities are existing sources if
significant site preparation work took place before NSPS became effective.
Exploratory wells are not considered new sources in any circumstance because it is not
considered significant site preparation.
Pretreatment Standards
Pretreatment standards are designed to prevent the discharges of pollutants that pass
through, interfere with, or are otherwise incompatible with publicly owned treatment works
(POTW). Since no offshore facilities currently discharge into POTWs, pretreatment
standards are not an issue for the offshore petroleum industry and are reserved.
For more information, contact Mary
Boatman.
