Procedures for Determining Needed Action for Point Source
Ground Water Pollution Events
If not already known, the Department will identify, if possible, the source(s) of contamination and the responsible party (or parties). The Department will notify the responsible party after the determination has been made. A responsible party is to complete the following protocol in accordance with Chapter 6, 001.
Part I. IMMEDIATE ACTION
Step 1. Initial Review
1) Perform an initial review to determine whether immediate action is needed to eliminate the existence or likelihood of an imminent and substantial threat to the public health and welfare or the environment or to mitigate the significantly increasing difficulty of cleanup if action is delayed, and if so, what actions are required. Base the review on as many of the items addressed in Steps 6 and 7 as possible.
a) imminent - a short time span (i.e., less than 90 days) 2) If the need for immediate action is apparent or if the need cannot be readily determined, proceed to Step 2 and work in conjunction with Department.
b) substantial - a significant impact on the public or environment (e.g., human illness or death, serious financial loss, severe ecological damage)
c) significant - if action is delayed, cleanup costs increase by one or two orders of magnitude
d) immediate actions - may include cleanup to at least an initial level, stabilization or containment, monitoring, shutdown/ termination of facility/activity, or any combination of measures. These actions are carried out by the responsible party.
3) If no immediate action is necessary (e.g., due to the nature of the pollution event developing over many years or moving slowly), proceed to Step 4.
Step 2. Implementation of Immediate Actions
1) Implement the immediate actions identified as required by Step 1 or as determined necessary in consultation with the Department.
2) Proceed to Step 3 when the immediate actions have been completed.
Step 3. Evaluation of Immediate Actions
1) Determine if immediate action has successfully eliminated the imminent and substantial threat to the public health and welfare and the environment or successfully mitigated any significant increase in difficulty of cleanup associated with delayed action.
2) If the immediate action was unsuccessful, return to Steps 1 and 2.
3) If requirements were met, proceed to Step 4.
Step 4. No Immediate Threat Present
Immediate action is not now needed, but additional measures for complete and permanent resolution of the problem may be required. Further assessment is necessary to determine the need for any final remedial action..
Part II. FINAL REMEDIAL ACTION
If at any time during the Part II assessment an immediate threat is identified, return to Step 1 (Part I).
Step 5. Preliminary Assessment
1) Complete a preliminary assessment to evaluate the possible threat of contamination to ground water. This assessment involves a review of existing information and require the collection of minimal or no field data. If it can be determined from this preliminary assessment that there is no threat of ground water contamination, proceed to Step 11. If ground water contamination is possible or likely, proceed to Step 6.
Step 6. Initial Site Assessment
1) Before this or any subsequent assessments are started, contact the Department to establish what information must be collected. In some cases where ground water contamination is immediately evident, or where ground water could not be used as drinking water, it may acceptable to combine Steps 6 and 7.
2) Complete an initial site assessment to determine if ground water has been or is likely to be impacted by the point source. Work will be approved by the Department prior to beginning the assessment. This assessment may involve test holes to determine the proximity of contaminants to ground water. If this initial assessment reveals that there is no threat of ground water contamination, proceed to Step 11; otherwise proceed to Step 7 under the direction of the Department.
Step 7. Detailed Site Assessment
1) Perform a detailed site assessment to determine the vertical and horizontal extent of the ground water contamination and its impact or potential impact to human health and/or the environment through examination of all pertinent factors. Work will be approved by the Department prior to beginning the investigation. 2) Provide the detailed site assessment to the Department. The Department may, at any time, request additional information.
Step 8. Define Preliminary Cleanup Levels
A remedial action class (RAC) is defined for pollution events in three types of ground water (or overlying soils) depending on the degree (or potential) of use of the ground water as drinking water. The extent of remedial action recommended will differ depending on the RAC of the contaminated (or likely to be contaminated) ground water. The RAC assigned will be determined from the condition of the ground water prior to the pollution event. The Department will assign the RAC based on information submitted by the responsible party in the detailed site assessment and other available information.
RAC-1. This category includes ground waters of Class GA and the portion of Class GB in a 500-foot radius (or greater, if determined necessary by the Department) around all private drinking water supply wells. RAC-1 is automatically assigned anytime a public or private drinking water supply well has been polluted.
RAC-2. This category includes ground waters of Class GB (except for the portion of Class GB placed in RAC-1) and Class GC(R).
RAC-3. This category includes, but is not limited to, ground waters of Class GC (except for Class GC(R) which was placed in RAC-2).
The RAC categories are not intended to represent a ground water classification system but rather a pollution event ranking scheme. It gives the Department a method to determine the importance of remedial action based on the use of the ground water. For instance RAC-1 is the category of highest rank; it represents that ground water actually being used for drinking water and that ground water intended to be used in a public drinking water supply. Therefore, RAC-1 events will normally receive the most extensive remedial action measures.
RAC-2 events involve ground water not now directly used as drinking water but having a reasonable potential to be used in the future. The potential for use exists if the ground water is located in a highly populated area or is part of a regional, high-yielding aquifer or if otherwise justified. The RAC-2 category also includes ground water with prior contamination that may be easily or cost-effectively treated to drinking water quality.
Pollution events will be of lowest importance, RAC-3, if the ground water involved is not used, or likely to be used, as drinking water. Generally remedial action measures will be least extensive for this category since the future use of ground water for drinking is improbable. Justification for assigning events to RAC-3 will be based on a combination of several different reasons. One reason for unusability is poor natural quality which makes the ground water unfit for human consumption. Insufficient yield is another reason the ground water may not be used for drinking. A third reason is historical contamination that occurred prior to the pollution event currently being investigated (see NRS § 81-1505(2)(d)). This past contamination may have rendered ground water unsuitable for drinking and uneconomical to treat. Past and present intensive land use is also a reason why ground water could be unusable as drinking water. This includes areas of concentrated industrial development or densely populated areas where ground water is likely to be contaminated or will not be used as drinking water.
The ranking of some events as RAC-3 does not mean there will be places in the State where wholesale contamination of ground water will be allowed. Departmental authority through its various programs to control practices or discharges that may contaminate ground water will still be in effect. RAC-3 events will be given a lower priority and less staff effort by the Department than RAC-1 or RAC-2 events.
RACs were developed primarily for use with the principal aquifer--the ground water commonly used for drinking. They will also be adapted for use with both deeper and perched ground water. When doing so, interconnections with overlying or underlying ground water of different quality will be considered.
Some contamination threats may occur in which the use potential of the ground water would be RAC-1 or RAC-2, but the soil, geology, and other site-specific characteristics are such that ground water contamination is virtually impossible. After an appropriate assessment, the event may be downgraded to RAC-3.
In every ground water contamination occurrence, certain minimum requirements will be imposed upon the responsible party, depending on the RAC. Cleanup of readily removable contaminants (e.g., free product) will be required. Additional cleanup and/or mitigation may also be required. If additional cleanup is not required, the remaining contaminated ground water will be managed and monitored to prevent any further damage.
In RAC-2, cleanup of readily removable contaminants (e.g., free product) will be required. If additional cleanup is not required, the remaining contaminated ground water will be managed and monitored to prevent any further damage.
In RAC-3, cleanup of readily removable contaminants (e.g., free product) will be required. Monitoring may also be necessary.
In addition to the minimum requirements listed above, RAC-1 and RAC-2 events are potentially subject to additional cleanup requirements. No further cleanup will be required for RAC-3 events based on drinking water usage. In certain cases,
1) The Department will set a preliminary cleanup level for additional cleanup required. in RAC-1 and RAC-2 events. The idealistic goal of the Department for any ground water cleanup is restoration - returning the ground water to its quality before contamination (background levels). Most (if not all) of the time these levels are impractical, unattainable, and (in some cases) unmeasurable. Therefore, the preliminary cleanup level will be based on the level necessary to maintain a drinking water use, although a preliminary cleanup level set at the background level may be considered in some cases. If a Department or EPA ground water/drinking water standard exists for the contaminant, it will be the level used. If there is no established standard, EPA's Ambient Water Quality Criteria, Health Advisories, and other documents will be used to set the preliminary cleanup level. The level will be set at the concentration which is estimated to result in a 1 in a 1,000,000 (10-6) excess cancer risk over a lifetime, at the concentration which is expected to result in no adverse health effect for longer-term or lifetime exposure, or the laboratory detection limit (if higher and within an acceptable range). If appropriate EPA data is nonexistent, data found in the literature will be used to determine the preliminary cleanup level. If sufficient information regarding acceptable levels is not found, the preliminary cleanup level will be set at background or the acceptable laboratory detection limit.
Sometimes the background level of a contaminant (as reported by the responsible party and approved by the Department) may be higher than what would be proposed as the preliminary cleanup level in the preceding paragraph. In these situations the background level will be used as the preliminary cleanup level.
In a few cases ground water cleanup based on drinking water use may not be sufficient to maintain other beneficial uses. For these unusual instances, preliminary cleanup levels will be based on the level needed to maintain the uses other than drinking water. This may necessitate cleanup even in RAC-3 events. Although the ground water in RAC-3 areas is not used as drinking water, it may serve other important uses (e.g., irrigation, industrial). It may also be necessary to set cleanup levels which protect streams and lakes from a contaminated ground water discharge that would violate surface water standards. Finally, the proximity to RAC-1 or RAC-2 areas, the likelihood of slow but eventual migration to these areas, and the cumulative effects of a series of contamination events must be considered when setting the preliminary cleanup level for RAC-3.
After receiving notification, either agree to the preliminary cleanup level or propose an alternate level. If a different cleanup level is proposed, it must be based on technological, economic, and/or risk analyses completed by the responsible party.
a) The technological analysis will determine if technologies exist to clean up the ground water to the preliminary cleanup level. If technologies do exist, report the various methods, including the contribution of cleanup processes which occur naturally. If cleanup to the preliminary level is not technologically possible, report what level of cleanup is attainable. As part of this analysis, the technological feasibility of various mitigative actions (e.g., supplying new sources of water and point-of-use treatment) should be investigated.
b) For an economic analysis, examine the economics of cleaning up to the preliminary level. If it is impossible to reach the preliminary cleanup level, report what level of cleanup is economically possible. Analyze the economic feasibility of mitigation instead of cleanup as well.
c) A risk analysis may include other factors, information, or evaluations not previously considered, to be based on the risk of the contamination harming human health and/or the environment.
If cleanup to the preliminary level is not attainable based on the foregoing analyses, report what portion of the ground water will remain contaminated following a lesser degree of cleanup. Given the technological considerations of cleanup, the appropriate calculations should be used in an attempt to define the three-dimensional boundary of the contamination plume under different remedial action scenarios (including no cleanup). The contamination plume, in this case, is defined as ground water where the concentrations of identified contaminants exceed their preliminary cleanup levels. For every cleanup scenario assessed, the economic impacts are to be defined. The relationship of the contaminated ground water boundary to existing users and discharge points of ground water are to be described.
If submitting an alternative cleanup level, include any supporting justification for an alternate cleanup level, a contamination maintenance program, a mitigation plan, or combination. The Department will consider the information contained in the justification on a case-by-case basis and establish a proposed final cleanup level or action. The level may be the same as the Department's preliminary cleanup level, the same as the proposed alternate cleanup level, or some other level.
The Department's decision on the remedial action necessary, including the proposed final cleanup level, will be placed on public notice. Any person may submit written comments on the proposed action or may request a hearing. Following the comment period and any hearing, the Department will notify the responsible party of the Department's final decision (including changes made as a result of a hearing).
2) Develop a workplan for performance of the final remedial action. The time frame for required action (including cleanup) will be the period of potential exposure to the contamination in the absence of any remedial action or 20 years, whichever is less. On a case-by-case basis, a longer period of time may be allowed if adequately justified by the responsible party. The workplan is subject to the Department's approval.
Step 9. Implementation and Review of Remedial Actions
1) Obtain any other permits from the Department that may be required to implement the workplan (e.g., UIC, NPDES).
2) Implement the remedial actions specified in the workplan.
3) Keep the Department apprised of cleanup efforts, and the Department will periodically review the effectiveness of the remedial actions. If the Department determines the long-term needs of protecting the public health and welfare and the environment have not been, or are not being, satisfied or if additional remedial action is necessary, the Department may require a return to Steps 7 and 8.
4) A request may be made to modify the required final remedial action during the implementation process. Any request must be accompanied by additional justification as described in Step 8. The Department will review the information, and if a change is appropriate, a public notice will be issued.
Step 10. Final Review
A final review will be performed by the Department to determine the need for any ongoing actions. These may include long-term monitoring to ensure cleanup levels are stabilized and maintained, periodic sampling of nearby supply wells, maintenance of installed structures, and annual case review. If acceptable cleanup levels were never reached, ongoing monitoring or maintenance may be necessary to ensure other ground water does not become contaminated.
1) Continue any ongoing actions determined to be necessary by the Department until ground water contamination is no longer a concern.
Step 11. Situation of No Threat to Ground Water Quality
The situation does not pose a threat to ground water quality. However, if other health, safety, or environmental concerns exist, they should be addressed by the appropriate Departmental procedures.