5 Colo. Code Regs. § 1002-61.28
The provisions of 25-8-202(1)(d) and (2) and 25-8-501 to 504 C.R.S. provide the specific statutory authority for the amendments to this regulation adopted by the Commission. The Commission also has adopted in compliance with 24-4-103(4) C.R.S., the following statement of Basis and Purpose.
BASIS AND PURPOSE:
Overview
These revisions are being made to include requirements for discharges to ground water via land application or impoundments. Such requirements have been anticipated since sections for these items, 6.14.2 and 6.15.0, have been "reserved" in the regulations since the 1981 revisions. These amendments are being made to provide specific regulatory guidance for protection of ground water standards or Division established numerical protection levels for discharges from land application systems and impoundments.
The concept of Division established numerical protection levels was brought forward in a joint Commission/Division policy statement for the implementation of the "Basic Standards for Ground Water", dated March 13, 1987. Its purpose is to provide a mechanism for regulatory control of individual discharges to ground water in the absence of site-specific classification and standards, while preserving the notion that the ground water in the vicinity of the activity will be formally classified by the Commission at some future time. The Commission intends that in developing numerical protection levels the Division would use the criteria in the "Basic Standards for Ground Water" so that, to the maximum extent possible, numerical protection levels would be consistent with standards that the Commission would be likely to establish. For example, in response to comments submitted by several parties, the Commission has clarified that only "reasonably probable" future uses should be considered by the Division in determining numerical protection levels. The Commission assumes that these provisions will be applied in a manner consistent with C.R.S. Section 25.8.302 . Any affected party can object to numerical protection levels and ask the Commission for site specific classification and standard-setting, which would override any inconsistent determination made by the Division. No classification and standard-setting authority is being delegated to the Division; rather, the Division is authorized to make a determination applicable to a specific facility unless and until the Commission reaches a different result through rulemaking.
Because of their nature, discharges from impoundments and land application systems are reaching state waters (ground water) whose beneficial uses must be protected. The Division will determine, after review of information supplied in the application, that one of three levels of permit conditions are necessary to protect the beneficial uses. The three levels are assumed to be:
Effluent limits may be determined by using published results of field studies or site-specific modeling results to predict attenuation of pollutants between the point of release and the point of compliance. Vadose zone monitoring is only anticipated to be used where a control regulation limiting the quality or quantity of a pollutant is in place or where the permittee would prefer such monitoring in lieu of installing ground water monitoring wells. In the latter case the Division will take further attenuation of pollutants beyond the monitoring device into account where available information (published material or modeling results) can support the proposed reduction and to the extent that beneficial uses are fully protected. Where the hydrologic or geologic characteristics in the vicinity of the discharge dictate, as shown through modeling or other appropriate analyses, attenuation of the mass pollutant(s) will be considered in establishing effluent limitations. The parties suggested that "background" concentrations of pollutants be taken into account by the Division in establishing effluent limitations. The Commission intends that, consistent with the regulatory approach that has been taken for surface waters, background concentrations will be taken into account in its determination of applicable standards and classifications or in a Division determination of numerical protection levels in accordance with the criteria in the "Basic Standards for Ground Water".
Authority to regulate impacts to ground water via recharge of effluent which is discharged to surface waters has been added but will be used only where information (such as studies which include formal field data collection and analysis) documenting such impacts exists. Where the impacts are well documented the Division will include effluent limits and a schedule of compliance, if necessary, to protect the ground water below the recharge zone. In other cases additional monitoring or studies may be required by the permit in order to fully document impacts before additional treatment is required.
The process for determining a "point of compliance" in the regulation has been referenced to the Basic Standards for Ground Water so that a consistent approach is maintained. For discharges to surface waters where the zone of recharge begins prior to the site boundary the Commission has determined that it is appropriate to establish the point of compliance using the same criteria for a direct discharge to ground water. The Commission recognizes that there may be situations where ground water is not impacted for a significant distance beyond the site boundary. In these cases the point of compliance may be set at a point no further downstream than the beginning of the zone of recharge. This is consistent with the overall framework the Commission has established that ground water contamination inconsistent with standards not be allowed beyond the site boundary.
The fate of pollutants as they travel through the soil/water matrix can be predicted using published material or modeling results but such predictions may be subject to significant error. Because the real possibility that undesirable concentrations of pollutants could reach and go beyond the point of compliance exists, requirements for detection wells or other verification monitoring and a control plan have been included. These elements will provide the permittee with a mechanism to detect excess contamination before it reaches the point of compliance and to eliminate such contamination if necessary to insure beneficial uses are protected and effluent limitation violations are avoided. If excess contamination is detected the permittee has the opportunity to take additional samples from existing or new wells, and/or use any other additional information to re-model the effluent/ground water mixture. If he can show that the effluent limits at the point of compliance can be met then remediation will not be required. Additional wells and/or monitoring may be required in order to verify new assumptions. If the results are negative then the permittee may request a variance from meeting standards for the effluent parameters of concern. It is only if such a variance request is denied that remediation will be required.
Several parties commented in rebuttal statements and at the rulemaking hearing that additional language was necessary to clarify the enforceability of the proposed amendments. The Commission has determined that a new section, 6.15.1(3), should be added to provide the necessary clarification.
Program Scope
Several parties proposed exclusions for activities which they believe would not have a significant impact on ground water. Specific criteria, identified in advance, were relied on to determine the types of activities which would be exempt from, or eligible for a waiver from, the requirements of the regulations. Elsewhere, as a matter of policy, the Commission has chosen to include facilities with a potential for causing an impact to ground water and structured the regulations with sufficient flexibility so that an unnecessary burden will not be placed on low impact facilities. An example of this is the provision in Section 6.15.8 which allows the Division to issue a permit without effluent limits, where it determines that the potential for adverse impact is minimal. Such permits would require reasonable monitoring and reporting to assure that the conditions upon which the decision was made to not require effluent limits do not appreciably change. This type of permit would generally be applicable to facilities whose discharge could be shown to have a minimal probability of impacting the underlying ground water. This would need to be demonstrated through documentation of geological factors (permeability rates, depth to ground water, etc.), hydrological factors (a large alluvial flow: discharge ration, small volume of discharge, etc.) or water quality factors which would preclude such an impact.
The Commission recognizes the expense of gathering ground water data and intends that information required of applicants will be tailored to the likelihood of an impact on the ground water.
The Commission feels it is appropriate for the Division to issue general permits for certain activities because of the limited nature of their impact on ground water. For example, it was suggested that a general permit be issued for temporary structures, which would most probably fit into the above-described categories of facilities with limited impacts. The decision as to what types of general permits may be appropriate is left to the Division, pursuant to its authority in Section 6.10.2.
Exclusions
The statutory reference, in Subsection 6.15.2 , to 25-8-202(7) C.R.S. is intended to exempt the activities identified therein from this regulation, provided those state implementing agencies are judged to be in compliance with the criteria of 25-8-202(7)(b)(ll).
Activities regulated by these agencies, where 'activity' is defined in part in Section 3.11.3 as "any operation that may discharge or cause a discharge of pollutants to ground water," are not subject to this permitting regulation, provided the Commission continues to determine that the implementing agencies are protecting present and future beneficial uses of ground water through those agencies' programs and that those agencies' actions are not causing a disproportionate burden on other dischargers or classes of dischargers who are subject to these, or implementing agencies', programs for implementing ground water standards established by the Commission.
In the event that Commission believes that an implementing agency is (1) not assuring compliance with the applicable ground water classifications and standards, (2) imposing a disproportionate burden on other dischargers or classes of dischargers subject to classifications and standards, or (3) not providing reasonable assurance that their implementation is in compliance with 25-8-202(7), the Division and the Commission shall make every effort to resolve apparent deficiencies, and any accompanying difference in understanding, through those interagency staff and Board/Commission communications discussed in the applicable Memorandum of Agreement.
In the event that these informal communications do not resolve the apparent deficiencies, the Commission may proceed to formal rulemaking to develop an appropriate regulatory procedure suited for those activities that appear to be inadequately regulated. This regulation, in its present form, has not been developed with those activities currently regulated by the implementing agencies considered. This regulation will not, therefore, be applied to such activities unless future Commission rulemaking finds it necessary and appropriate to broaden the scope of applicability.
Some parties expressed concern regarding whether impoundments that are part of a wastewater treatment system at a mining operation are intended to be covered by this regulation. Consistent with Section 25-8-202(7), the potential ground water quality impacts from such structures would be addressed in the first instance by the Mined Land Reclamation Division. The Commission assumes that the report now being prepared by the Mined Land Reclamation Division to describe how its programs will assure compliance with water quality standards and classifications will address these types of facilities. Only if it were determined at a later date that such facilities have existing or potential adverse ground water quality impacts that are not being adequately addressed by the Mined Land Reclamation Division would it be appropriate for the Commission to consider further rulemaking in this regard. The Commission recognizes that there are a number of existing programs which strive to protect ground water quality form certain types of activities. The Commission has adopted these amendments because there are other activities which may impact ground water and are not covered by existing programs. But, at the same time the Commission has provided a number of exemptions from the regulation in order to avoid duplicate regulations.
Exclusions were provided for the following seven types of activities in addition to those activities excluded under Section 6.15.2.
Raw and potable water storage impoundments, which would include impoundments filled with water supplied by a public water supplier, are not expected to impact ground water because of the quality of water contained in them. Other impoundments used in water treatment (presedimentation and filter backwash) are not expected to have a negative impact; however, the Commission reserves the right to eliminate the exclusion for these types of impoundments if information to the contrary is developed.
Stormwater retention and detention ponds are not expected to have a negative impact on groundwater since they generally will be adjacent to a stream and any seepage would drain to the stream itself. They will be covered by future amendments to the regulation specifically for stormwater. Again, the Commission reserves the right to delete this exclusion if negative impacts are discovered.
Impoundments installed under the UMTRA are required to be adequately lined and no impact from them is expected.
The Hazardous Materials and Waste Management Division will continue to have responsibility for the regulation of discharges to ground water from solid waste impoundments that are not part of a wastewater treatment system for which a facility is required to obtain a CDPS permit for surface discharge. An exception to regulation under this rule also has been provided for any portions of a system (e.g. a sludge storage or disposal site) that are already covered by a certificate of designation issued pursuant to the Solid Waste Disposal Sites and Facilities Act.
The Water Quality Control and Hazardous Materials and Waste Management Divisions recognize the potential for overlap between their respective programs and held discussions to determine an efficient way to avoid duplication. They agreed that if a system is already covered by a CDPS permit it made good sense to confine regulation of that system to one agency. The exception for portions of systems which already have a certificate of designation was made in recognition of the fact that a substantial analysis of potential impacts as well as a requirement to install a ground water monitoring and reporting system will be required for such systems. This in turn, would minimize the probability on an impact to ground water.
The definition of "tank" which is patterned after the RCRA hazardous waste regulations, has been included (Section 6.3.0 and an exemption has been provided for tanks which do not result in a discharge of contained liquids to state waters. This exemption replaced a previously proposed exemption for certain structures at mechanical wastewater treatment facilities, and should cover such structures and similar structures at other facilities. In doing this the Commission intends to parallel the distinction between tanks and impoundments in the RCRA regulations in recognition of the fact that tanks are designed and constructed to be impermeable. Where the design or construction of a tank has not been done in a manner which will provide the expected impermeability, or where poor maintenance has allowed the tank to deteriorate to the point where it is leaking, the owner is required to obtain a permit if a discharge to ground water will occur.
In general, because the design of a majority of tanks has been reviewed by a regulatory agency, the Commission does not foresee a large number of tanks being required to be covered by a permit. Therefore, positive certification by tank owners that certain design, construction, and maintenance criteria have been met is not being required at this time.
However, should the owner of a tank become aware of a significant loss of fluid from that tank then they are expected to notify the Division immediately so that a determination regarding existing or future ground water impacts can be made.
Discharges to ground water from underground injection wells which are covered by a permit issued pursuant to the Underground Injection Control (UIC) provisions of the Safe Drinking Water Act are not expected to impact ground water to an unacceptable degree since the UIC permits contain conditions which are aimed at protecting drinking water uses.
Land applications of sludge for beneficial use, consistent with the Domestic Sewage Sludge Regulations, should be protective of ground water since the Board of Health, in promulgating those regulations, took ground water impacts into account. Once the federal sludge disposal regulations are finalized, changes will be made to the State sludge regulations which should result in additional protection.
Other exclusions were requested for recharge of raw water in a canal and for feedlots. The Commission understands that these activities are not subject to permit requirements due to statutory exemptions provided at 25-8-503(5) and 25-8-504(2), respectively. The Commission anticipates that any ground water impacts from feedlots will be addressed in the upcoming triennial review of the Feedlot Control Regulation (8.1.0). impacts from diversion of surface waters into canals for recharge are expected to be minimal.
Application Requirements
The requirements for submittal of information by applicants who discharge to ground water are general in nature. The physical aspects of each site will be unique and it is impractical to include application requirements which would be specific enough to address every situation. The Division has indicated that they intend to establish tiered application requirements based on the applicants size, the potential for impacting ground water and other site-specific considerations.
Land Application
Land application is being divided into two areas, land disposal and land treatment, based on the Division's experience with the types of land application systems which are being installed in the state and the function of those systems. Land disposal generally is used as a means of providing irrigation water for public use or agricultural areas and land treatment is self explanatory but may contain some functional elements of a land disposal system. Effluent limitations for land disposal systems will be set at some point prior to application and will be based on protection of ground water without any further treatment beyond that point. Ground water monitoring will generally not be required in such cases. The minimum levels of treatment described in Section 6.9.2 (technology based treatment) will be required, to provide a consistent approach throughout the state.
Impoundments
The Division's design criteria requires that domestic wastewater and storage impoundments be sealed such that seepage from the impoundment does not exceed one-thirty-second of an inch per day (0.92 X106 cm/sec). Because this criteria has been used in the design of numerous domestic facilities, and it generally is considered to require an "impervious" liner to meet it, Section 15.9 allows the Division to grant a waiver of the requirement to obtain a permit for impoundments where seepage does not exceed 1x106 cm/sec. Test methods which would be acceptable in determining the seepage rate from a soil impoundment are described in "Design, Construction, and Evaluation of Clay Liners for Waste Management Facilities (EPA/530/SW-86/007F, November, 1988)". Test methods which would be acceptable for determining the seepage rate from impoundments which are lined with compacted soil or an artificial liner are described in "Lining of Waste Containment and Other Impoundment Facilities (EPA/600/288/052, September, 1988". Additional test methods which are not described in these documents will be considered on a case-by-case basis. In general, the accuracy of the test method will be required to be higher for those impoundments which are expected to have a greater potential for impact on ground water quality. Therefore, small facilities which contain only domestic wastewater and which would not be expected to have an adverse impact, will be allowed to use simpler methods, such as a flow balance, to demonstrate the seepage rate. The Commission believes it is appropriate that this waiver be provided for both lined and unlined impoundments that meet the impermeability test, so long as the impoundment can be properly maintained throughout its design life. If this test cannot be met then there is a potential for adverse impact to the ground water quality and a permit should be required.
Implementation
A significant number of facilities may be impacted by these regulations. Therefore, in order to proceed in a rational fashion without exceeding the Division's resources, all new facilities will be required to comply immediately and existing facilities, as prioritized by the Division, will be required to apply for a permit within sixty days of notification or, at a maximum, within two years of the effective date of the regulation. An exception is provided for facilities whose land application systems or impoundments are currently described in the rationale for a CDPS permit. These facilities will be required to submit the appropriate information at the time of renewal of the CDPS permit.
The Commission has determined that the effective date of these amendments to the Discharge Permit Regulations will be July 1, 1991. This has been done in order to allow the Division time to pursue funding for necessary additional program support during the 1991 legislative session.
PARTIES TO THE PROCEEDINGS OF THE PUBLIC RULEMAKING HEARING STATE DISCHARGE PERMIT SYSTEM NOVEMBER 5, 1990
5 CCR 1002-61.28