Michael E. Norman
ENSR Consulting & Engineering
Houston
Sunil Kapoor
ENSR Consulting & Engineering
Houston
G. Allen Smalley Jr.
ENSR Consulting & Engineering
Houston
Bruce M. Daniel
ENSR Consulting & Engineering
Redmond, Wash.
Since 1990, two U.S. Environmental Protection Agency (EPA) regulations have essentially made all wastewater produced in U.S. refineries hazardous wastes.
These two rules--the Toxicity Characteristic (TC) rule and the Primary Sludge listing--can have severe repercussions on a refinery's wastewater treatment System.
This second article in a three-part series presents an overview of the hazardous waste regulations most likely to have a major impact on refinery wastewater systems.
TC RULE
The TC Rule, promulgated Mar. 29, 1990 (55 FR, 11797), expanded the list of characteristically toxic compounds by adding 25 organic chemicals (Table 1). The list had previously included eight metals and six organic pesticides and herbicides, but no other organics.
Wastewater comprised over 90% of the newly regulated wastes under this rule, and wastewater sludges are a major portion of the remainder.
The TC rule changed the method of determining whether a solid waste contains characteristic constituents. The new method is called the Toxicity Characteristic Leaching Procedure (TCLP). If the leachate from this test contains toxic constituent concentrations that exceed the regulatory threshold, the waste is considered hazardous.
For solid wastes, it is possible that the leachate concentration will be below the threshold hazardous level, even if the total concentration in the waste itself is above the threshold. In this case, the waste is not subject to RCRA hazardous waste regulations.
For wastewater, however, the concentration in the wastewater is the concentration upon which the hazardous determination is made.
The TC compounds most likely to be found in refinery wastewater streams, and their threshold concentrations, are:
- Arsenic, 5.0 ppm
- Chromium, 5.0 ppm
- Mercury, 0.2 ppm
- Benzene, 0.5 ppm
- Cadmium, 1.0 ppm
- Lead, 5.0 ppm
- Selenium, 1.0 ppm.
Benzene, with a defined hazardous threshold of 0.5 ppm, is the compound of most concern in refinery wastewater systems.
IMPOUNDMENTS
Currently, the major impact of the TC rule on wastewater systems is on the use of impoundments (55 FR 39410, Sept. 27, 1990). Impoundments that receive or store waste that exceeds TC limits must be Resource Conservation and Recovery Act (RCRA) permitted, and must meet the following Minimum Technical Requirements (MTRs) by Mar. 29, 1994:
- Double liner
- Leachate collection system
- Groundwater monitoring program.
Existing impoundments must either be retrofitted to meet these requirements by Mar. 29, 1994, or stop receiving TC-hazardous wastes by that date. These units will also have to be closed, under stringent RCRA requirements, within 6 months of last receipt of waste.
In some cases, an operator may delay closure if the impoundment will be kept in nonhazardous operation. However, this requires that all hazardous wastes, including sludges and contaminated soil, be removed to the extent practicable. This option would preclude closure in place and require more costly off site treatment and disposal.
A key provision is that compliance is measured at the entrance to the impoundment, not after the entering stream is mixed with water already in the impoundment. This means that TC rules apply if the wastewater stream entering the impoundment exceeds TC levels, even if it is diluted to nondetectable levels by water already in the impoundment.
This interpretation has a significant influence on the continued use of impoundments to manage rainwater that falls inside battery limits, because this rainwater may become contaminated from surface spills and leaks.
Even if a facility has a totally segregated stormwater system, impoundments would be subject to this rule if any of the rainwater that enters the impoundment is TC hazardous, even if samples taken from the impoundment never exceeded TC limits.
Facilities need to carefully evaluate whether other areas that may contain wastewater meet the definition of a surface impoundment. A surface impoundment is defined in 40 CFR 260.10 as, "a facility or part of a facility which is a natural topographic depression, manmade excavation, or diked area formed primarily of earthen materials (although it may be lined with manmade materials), which is designed to hold an accumulation of liquid wastes or wastes containing free liquids, and which is not an injection well."
Surface drainage ditches could be included in this definition, if not properly designed and maintained to eliminate areas of standing water. Ditches or surface sewers that hold water could be construed as "storage" basins or impoundments, rather than conveyances, which are exempt. Other diked areas, such as tank farms, may also meet the definition of an impoundment.
BIOLOGICAL TREATMENT
Biological treatment units, such as activated sludge or aeration basins, may be required to meet MTR standards if the influent water to the unit is TC hazardous. RCRA Section 3005(j)(3) does provide an exemption from MTRs for these impoundments if:
- The impoundment contains wastewaters undergoing aggressive biological treatment.
- It is part of a wastewater treatment facility subject to regulation under Section 307(b) or 402 of the Clean Water Act (CWA).
- It is in compliance with groundwater monitoring requirements.
The exemption is not automatic. Facilities have to submit evidence for exemption within 2 years after promulgation of the TC regulation, which was Mar. 29, 1992.
RCRA Section 3005(j) also provides two other exemptions, under very limited circumstances, which will not be discussed in this article.
SYSTEM DESIGN
Rather than retrofit or build impoundments to meet RCRA MTR requirements, many facilities are opting to segregate clean stormwater and store and treat process wastewater in tanks that are currently exempt from RCRA requirements (to be discussed later).
Compliance with Benzene National Emission Standards for Hazardous Air Pollutants (Neshaps) will remove major sources of benzene from the wastewater. However, it will not necessarily control those streams that have between 0.5 and 10.0 ppm benzene, which would still be TC hazardous. Process upsets could also lead to process wastewater that would become TC hazardous.
Construction of tank systems to replace impoundments is the most prudent course of action. Impoundments that meet MTR standards could be built, but the cost for large-capacity units may exceed the cost of tanks.
Future land disposal restrictions (also discussed later) could negatively affect the use of impoundments, even if they meet MTRs. New air regulations will probably require control of emissions from wastewater systems. In most cases, it will be less expensive to control air emissions from tanks than from impoundments.
Stormwater presents additional problems, even if segregated from process water. The first rainwater that falls may become TC hazardous by contamination from spills and leaks.
After the "first flush" rainfall has cleaned off the surface contamination, subsequent stormwater may not be hazardous. However, as explained above, surface impoundments under this scenario still have to meet MTRs.
A facility may choose to handle all stormwater in tank systems, totally eliminating impoundments. For some areas of the country, however, this may be impractical because of large rainfall volumes.
An alternative is a system that routes the first flush stormwater to tanks, and allows the remainder of the stormwater to flow into impoundments, under the assumption (which can be tested) that it will not be hazardous. If process water does not overflow into the stormwater system, and proper housekeeping practices keep surface spills cleaned up, this is a reasonable approach.
PRIMARY SLUDGE
On Nov. 2, 1990, EPA published the final rule for what is referred to as the "Refinery Primary Sludge Listing" (35 FR 46354). The listing designates most sludges generated in petroleum refinery process wastewater systems, upstream of aggressive biological treatment units, as a listed hazardous waste, with waste codes F037 or F038.
Because these are listed wastes, they do not necessarily have to exhibit any hazardous constituents, as discussed under the TC rule. These wastes may also be generated by process wastewater that is not TC hazardous.
The listing became effective on May 2, 1991. On May 13, 1991, EPA published an interim final rule exempting noncontact, once-through cooling water (36 FR 21955). API separator sludges and Dissolved Air Flotation (DAF) float retained their previous listing designations as K048 and K051, respectively.
The primary sludge rule applies regardless of where the sludges are generated or whether the generation was intentional. The F037 and F038 sludges may be generated in sewers, sumps, ditches, tanks, separators, air/gas flotation units, or any other portion of the wastewater system that generates sludges from the gravitational, physical, or chemical separation of oil, water, and solids.
As with the TC rule, the principal impact of the primary sludge rule is on the use of impoundments. Surface impoundments used to manage process wastewater that could generate these wastes have to be RCRA permitted. They also must comply with MTRs by Nov. 2, 1994, or cease receiving/generating the sludges by that date. Affected impoundments built after May 2, 1991, have to meet MTRs when built.
Technically, if no solids or float are generated in the impoundment, these standards do not have to be met. However, this is generally difficult to achieve in practice.
EXEMPTIONS
Much of the discussion about impoundments affected by the TC rule also applies to impoundments affected by the primary sludge rule. There are two important exemptions, however, for biological treatment and stormwater. Sludges generated in, or following, aggressive biological treatment are not covered by the rule, but may be regulated at a later time. EPA defined four types of aggressive biological treatments:
- Activated sludge
- Trickling filters
- Rotating biological contactors
- High-rate aeration (6 hp/million gal volume;
Sludges generated in segregated stormwater units that receive flows only during storm events are also exempt from the listing, even if they receive process water during those storm events. Conversely, sludges generated in stormwater units that also receive dry weather process water flow are not exempted.
Impoundments used for aggressive biological treatment or impoundments receiving water only when it is raining are not regulated under this rule and do not have to meet MTRs at this time. However, if the influent to these units is TC hazardous, MTRs will still be required under that rule.
SYSTEM DESIGN
The general effect of this rule is to encourage both the use of totally segregated stormwater systems and the elimination of impoundments in the process wastewater system. By using a segregated system, impoundments can still be used to handle large quantities of nonhazardous stormwater.
Even if a facility decides to handle stormwater in tanks because of the TC rule, it should be segregated from process water to reduce the amount of hazardous waste that will have to be treated and disposed of at a high cost.
Stormwater systems typically generate large volumes of solids washed from process unit pads, roads, tank farms, and other areas. When combined with oily process water, these solids end up as hazardous primary sludges which have to be treated and disposed of at a high cost. By segregating stormwater, generation of hazardous wastes in the process water system will be reduced.
LORS
Land Disposal Restrictions (LDRs) require that hazardous wastes be treated to reduce the level of hazardous constituents before disposal in a permitted land-based unit (such as a landfill or surface impoundment) that meets MTRs.
Under the terms of a court settlement, EPA agreed to issue final treatment standards for primary sludge by May 31, 1992, and for TC wastes by Apr. 30, 1993.
Treatment standards are effective immediately upon promulgation unless EPA finds that sufficient treatment capacity does not exist, and consequently issues a national capacity variance.
There is a conflict between the TC and primary sludge rules and LDRs, regarding the time allowed to retrofit impoundments to meet MTRs. The TC and primary sludge rules allow a facility 4 years from promulgation of the rule to retrofit impoundments--Mar. 29, 1994, and Nov. 2, 1994, respectively.
However, RCRA Section 3005(j)(11) prohibits the placement, for storage or treatment, of any waste subject to LDRs in an impoundment that does not meet MTR standards. It also requires that hazardous residues be removed at least annually. RCRA 3004(h)(4) stipulates that, even if there is a national capacity variance, surface impoundments can be used only if MTRs are met.
These rules have the effect of forcing impoundments to meet MTR standards prior to the 1994 compliance deadlines, possibly as early as May 1992 for F037/38 sludges.
On Feb. 4, 1992, EPA published a proposed rule (57 FR 4170) to clarify this conflict. This rule would allow non-MTR impoundments to receive untreated wastes subject to LDRs during a period of a national capacity variance.
Impoundments would still have to meet MTRs within 4 years of the waste becoming classified as hazardous, or whenever the national capacity variance ends, whichever is earlier.
EPA has proposed (57 FR 958, Jan. 9, 1992) that the treatment standards for primary sludge be the same as those for K048-51 refinery wastes, which are based on incineration, thermal desorption, or solvent extraction.
EPA has issued an Advance Notice of Proposed Rulemaking for TC wastes (56 FR 55159, Oct. 24, 1991). Per this notice, EPA is considering concentration-based standards for wastewater, which will be at or below the characteristic level for the new TC wastes. EPA has also proposed the following in regard to F037/38 wastes:
- A capacity variance for wastes generated in surface impoundments only. The variance does not apply to sludges generated anywhere else. The maximum length of the variance is 2 years and it can be revoked any time EPA determines that sufficient capacity exists. This variance is based on the lack of available MTR impoundments or tanks in which to accumulate these sludges, and not on the lack of actual treatment capacity.
- Sludges placed in impoundments (with or without MTR standards) have to be removed annually. Based on the agency's comments, these materials would have to be treated before disposal.
- If treatment capacity is available, wastes in an impoundment will have to be removed and treated when the impoundment is closed. Thus, impoundments must be "clean-closed."
Based on these proposed rules, refineries will still have until May or November 1994, to retrofit or eliminate impoundments managing TC wastes or primary sludge, respectively, unless the capacity variance is eliminated. However, sludges will have to be removed, treated, and disposed of annually.
In addition, the requirement to ultimately clean-close non-MTR impoundments will be substantially more expensive than the close-in-place options (such as stabilization), which many facilities are planning.
To minimize closure costs (assuming the proposed rules are adopted), the following options should be considered:
- Begin a program to biologically treat the wastes in the impoundments to reduce the volume that will have to be removed, treated, and disposed of upon closure.
- Investigate proposed corrective action rules (55 FR 30797, July 27, 1990) which may allow use of Corrective Action Management Units (CAMUs) to avoid LDRs.
RCRA REQUIREMENTS
RCRA imposes specific requirements on facilities and units used to store, treat, or dispose of hazardous wastes. These requirements include:
- Management procedures
- Permitting
- Double liners
- Leak detection and leak collection systems
- Groundwater monitoring
- Emission controls
- Closure plans
- Financial assurance.
There are two exemptions in 40 CFR 261.4, however, that apply to wastewater operations and are critical to compliance and planning for future activities. These exemptions apply to most units that are part of a wastewater system associated with:
- Industrial discharges that are mixed in a sewer with domestic sewage that flows to a Publicly Owned Treatment Works (POTW) under CWA, Section 307(b); and
- Industrial discharges that are regulated by CWA Section 402 (National Pollutant Discharge Elimination System [Npdes] permit).
These exemptions essentially cover all units in the wastewater system that meet the definition of "tank," from process unit drain to facility discharge. Surface impoundments are specifically not exempted and have to meet RCRA requirements, as discussed earlier.
Care should be taken so that certain units are not construed as impoundments instead of as tanks eligible for the exclusion. EPA's interpretation of the tank definition (40 CFR 260.10) was recently upheld in a court case, and includes the "foundation" and "water-tightness" tests: "the unit must be completely self supporting and watertight when filled to capacity and, hypothetically removed from the ground."
Neither of these "tests" are expressly contained in the tank definition in 40 CFR 260.10.
The court also accepted EPA's interpretation that the definition of "tank" and "impoundment" are mutually exclusive.
This interpretation could cause some units, such as concrete-lined aeration basins, sumps, and ditches, to be ruled as impoundments, and thus become ineligible for the wastewater treatment tank exemption.
A third exemption could have an indirect affect on some wastewater operations:
- Water recovered and reinjected during free-phase hydrocarbon recovery operations until Jan. 25, 1993.
If the exclusion is not extended, recovered water from these operations would have to be treated before reinjection, placing an additional burden on the treatment facility.
If the existing wastewater treatment facility is to be used for treatment of this water, the Npdes permit should be reviewed to make sure groundwater is listed as an allowable stream. If it is not, the permit needs to be amended to keep the RCRA exemption intact.
If a separate facility is constructed to treat the recovered water, it would have to meet RCRA standards because it might not qualify for an exemption.
SYSTEM DESIGN
Although most of a refinery wastewater system can usually qualify for an exemption from RCRA, new construction or design should consider the possibility that the exemption could be limited or even eliminated in the future.
When making design decisions, compare the cost of building to meet RCRA standards, or building to enable easy upgrades, to the cost and risk of having to upgrade to RCRA standards in the future.
For example, constructing a tank with a double bottom or liner so that it could be modified to meet RCRA leak detection requirements at later date is usually far less expensive than upgrading standard tank design.
TSD FACILITIES
On June 21, 1990 (55 FR 25452), EPA issued the first of two standards limiting organic emissions from hazardous waste treatment, storage, and disposal (TSD) facilities. The first set of rules covered process vents and equipment leaks (40 CFR 264-65, Subparts AA and BB), and was effective Dec. 21, 1990.
Process vents associated with the treatment of hazardous wastes having 10 ppm or more total organics are required to have control devices that reduce total organic emissions by at least 95%.
Leak standards are imposed on any equipment that contains or contacts a hazardous waste stream containing 10% or more total organics, and apply to emissions from valves, pumps, compressors, and pressure relief devices.
The standard requires monthly monitoring to determine that there are no detectable emissions, which are defined as 500 ppm over background. If emissions are detected, the rule has a mandated period of time in which to attempt and make repairs.
The second set of standards, covering surface impoundments, tanks, containers, and miscellaneous units, was proposed on July 22, 1991 (56 FR 33490). EP set a target date of July 199 for issuing the final rule.
The proposed rule sets single action level of 50 ppm Volatile Organic Compounds (VOCs) in the hazardous waste, and require 95% emission control on an unit that contains or contacts a hazardous waste exceeding this level.
The rule does not apply to hazardous wastewater stored or treated in units exempted from RCRA permitting. Impoundments would not be exempt, but it is unlikely that waste streams managed in impoundment would exceed 500 pp VOCs.
However, if an impoundment is affected, the effective date for emission controls could be as early as late 1992. This, of course, is prior to 1994, when MTRs will be required for impoundments managing hazardous wastes.
For those facilities planning to construct MTR impoundments to handle hazardous wastewaters, the total expected VOC concentration should be determined, because installing emission controls on impoundments can be both difficult and expensive.
Biological treatment systems, the second largest source category targeted by this rule, are not exempted. Affected biotreatment systems would have to be contained in an air-supported or rigid structure with emission controls on the vent gas. No detectable emissions will be allowed.
Conversion to a bioreactor tank system may be a more reasonable alternative. When planning new or upgraded wastewater systems, the impact of this rule should be considered in case the RCRA exemption is lost in the future.
RCRA REAUTHORIZATION
RCRA reauthorization bills are currently being drafted by the U.S. Congress and Senate. Although many of those involved have vowed to get a bill out of committee this year, it will probably be in 1993 instead.
Several issues that are likely to be included in the bill may affect wastewater systems. These are briefly discussed below, along with implications for current upgrades.
- RCRA standards applied to wastewater systems
Industrial wastewater Systems operating under Npdes permit authority may lose the RCRA exemption now in effect for many parts of the system if the water is hazardous. This would mean many parts of the system, including sewers, sumps, tanks, and biological treatment units, could have to meet RCRA standards.
Wastewater upgrades should be designed to meet RCRA standards or to allow for easy upgrade in the future.
- New standards for nonhazardous industrial impoundments
The U.S. Senate is considering imposing regulations designed to protect groundwater at surface impoundments that receive industrial nonhazardous wastes. The requirements would be similar to those recently imposed under Subtitle D for municipal landfills, and would include groundwater monitoring, liners, leak detection systems, and overtopping controls.
New impoundments, or upgrades of existing impoundments, for nonhazardous water (including stormwater) should probably include at least a single liner, with provisions to add a leak detection system at a later date. This rule, along with the one above, may force all biotreatment to take place in tanks rather than in impoundments.
- Additional hazardous wastes
The new act will probably broaden the definition of hazardous waste characteristics to include acute toxicity, bioaccumulation potential, aquatic toxicity, and carcinogenicity. Wastewater streams not currently hazardous may become hazardous in the future, triggering many of the additional controls discussed in this article.
Although not part of RCRA reauthorization, EPA has also agreed (as part of a court settlement with the Environmental Defense Fund) to consider listing as hazardous, 15 specific refinery wastes by Oct. 31, 1996. These wastes include various process sludges and spent catalysts that may affect some wastewater systems.
EPA also agreed to study other additional refinery waste streams by June 30, 1996, to determine if they should be listed as hazardous wastes in a future rulemaking. Included in these possible waste streams are off spec products, desalter sludges, resins, and treater clay.
- Mandated waste minimization
The new act will require waste minimization and set specific standards for reductions. Information being collected as part of new SARA 313 Form R reports will be used to establish baselines. Wastewater systems offer a large potential for achieving waste reductions if you consider every gallon of water discharged as a waste.
Copyright 1992 Oil & Gas Journal. All Rights Reserved.
