Alaska Admin. Code tit. 20, § 25.1310 – Post-injection site care; site closure; monitoring timeline

(a) A storage operator shall prepare, maintain, and comply with a plan for post-injection site care and site closure that meets the requirements of this section and is acceptable to the commission. The requirement to maintain and implement an approved plan is directly enforceable regardless of whether the requirement is a condition of the storage facility permit. The storage operator shall submit the post-injection and site care and site closure plan as part of a storage facility permit application under 20 AAC 25.1080.
(b) The post-injection site care and site closure plan required under (a) of this section must include the following information:
1. (1) the pressure differential between pre-injection and predicted post-injection pressures in the injection zone;
2. (2) the predicted position of the carbon dioxide plume and associated pressure front at site closure as demonstrated in the area of review evaluation required under 20 AAC 25.1070(c)(1);
3. (3) a description of post-injection monitoring location, methods, and proposed frequency;
4. (4) a proposed schedule for submitting post-injection site care monitoring results to the commission pursuant to 20 AAC 25.1610; and,
5. (5) the duration of the post-injection site care timeframe and, if approved by the commission under AS 41.06.170(a)(3) and this section, the demonstration of the alternative post-injection site care timeframe that ensures non-endangerment of underground sources of drinking water.
(c) A storage operator shall specify in a post-injection site care and site closure plan which wells will be plugged and which shall remain unplugged to be used as subsurface observation wells. A subsurface observation or groundwater monitoring well as approved in the plan must remain in place for continued monitoring during the closure and post closure periods.
(d) Upon cessation of injection of carbon dioxide into a storage reservoir, but before application for a certificate of completion, the storage operator shall either submit an amended post-injection site care and site closure plan or demonstrate to the commission through monitoring data and modeling results that no amendment to the plan is needed. An amendment to the post-injection site care and site closure plan must be approved by the commission and be incorporated into the storage facility permit and is subject to the permit modification requirements of 20 AAC 25.1410 or 20 AAC 25.1430, as appropriate.
(e) At any time during the life of the storage facility, a storage operator may modify and resubmit the post-injection site care and site closure plan for the commission's approval not more than 30 days after the change.
(f) Upon cessation of injection of carbon dioxide into a storage reservoir, and before a storage operator applies for a certificate of completion under 20 AAC 25.1320, the storage operator shall monitor the site to show the position of the carbon dioxide plume and pressure front and demonstrate to the commission that underground sources of drinking water are not endangered. Following the cessation of injection, the storage operator shall continue to conduct monitoring as specified in the commission-approved post-injection site care and site closure plan for at least 50 years or for the duration of the alternative timeframe approved by the commission pursuant to requirements in (h) of this section, unless the storage operator makes a demonstration under (g) of this section. A post-injection site care plan must require the storage operator to continue monitoring the storage facility until the storage facility no longer poses a danger to underground sources of drinking water and the demonstration under (g) of this section is submitted by the storage operator and approved by the commission.
(g) Notwithstanding (f) of this section, if the storage operator demonstrates to the satisfaction of the commission before 50 years after cessation of carbon dioxide injections, or prior to the end of the approved alternative timeframe based on monitoring and other site-specific data, that the storage facility no longer poses a danger to underground sources of drinking water, the commission may approve an amendment to the post-injection site care and site closure plan to reduce the frequency of monitoring or may authorize site closure through a certificate of completion under 20 AAC 25.1320 before the end of the 50-year period or before the end of the approved alternative timeframe, if the commission finds substantial evidence that the storage facility no longer poses a risk to underground sources of drinking water. If the commission does not approve the demonstration, the storage operator shall submit to the commission a plan to continue post-injection site care until a demonstration can be made and approved by the commission.
(h) The commission may approve, in consultation with the United States Environmental Protection Agency, an alternative post-injection site care timeframe other than the 50-year default under AS 41.06.170(a)(3), if a storage operator demonstrates during the permitting process under 20 AAC 25.1080 that an alternative post-injection site care timeframe is appropriate and ensures non-endangerment of underground sources of drinking water. The demonstration must be based on significant, site-specific data and information including all data and information collected pursuant to 20 AAC 25.1080 and 20 AAC 25.1060 and must contain substantial evidence that the storage facility will no longer pose a risk to underground sources of drinking water at the end of the alternative post-injection site care timeframe. A demonstration of an alternative post-injection site care timeframe must include consideration and documentation of
1. (1) the results of computational modeling performed pursuant to delineation of the area of review under 20 AAC 25.1070;
2. (2) the predicted timeframe for pressure decline within the injection zone, and any other zones, such that formation fluid may not be forced into an underground source of drinking water; or the timeframe for pressure decline to pre-injection pressures;
3. (3) the predicted rate of carbon dioxide plume migration within the injection zone, and the predicted timeframe for the cessation of migration;
4. (4) a description of the site-specific processes that will result in carbon dioxide trapping including immobilization by capillary trapping, dissolution, and mineralization at the site;
5. (5) the predicted rate of carbon dioxide trapping in the immobile capillary phase, dissolved phase, or mineral phase;
6. (6) the results of laboratory analyses, research studies, or field or site-specific studies to verify the information required in (4) and (5) of this section;
7. (7) a characterization of the confining zone including a demonstration that it is free of transmissive faults, fractures, and micro-fractures and of appropriate thickness, permeability, and integrity to impede fluid, e.g., carbon dioxide, formation fluid, movement;
8. (8) the presence of potential conduits for fluid movement including planned injection wells and project monitoring wells associated with the proposed storage facility or any other projects in proximity to the predicted or modeled, final extent of the carbon dioxide plume and area of elevated pressure;
9. (9) a description of the well construction and an assessment of the quality of plugs of all abandoned wells within the area of review;
10. (10) the distance between the injection zone and the nearest underground sources of drinking water above or below the injection zone; and
11. (11) any additional site-specific factors required by the commission.
(i) Information submitted to support the demonstration in subsection (h) must meet the following criteria:
1. (1) all analyses and tests performed to support the demonstration must be accurate, reproducible, and performed in accordance with the established quality assurance standards;
2. (2) estimation techniques must be appropriate and United States Environmental Protection Agency-certified test protocols must be used where available;
3. (3) predictive models must be appropriate and tailored to the site conditions, composition of the carbon dioxide stream and injection and site conditions over the life of the storage facility;
4. (4) predictive models must be calibrated using existing information where sufficient data are available;
5. (5) reasonably conservative values and modeling assumptions must be used and disclosed to the commission whenever values are estimated on the basis of known, historical information instead of site-specific measurements;
6. (6) an analysis must be performed to identify and assess aspects of the alternative post-injection site care timeframe demonstration that contributes significantly to uncertainty; for the purpose of this paragraph, the storage operator must conduct sensitivity analyses to determine the effect that significant uncertainty may contribute to the modeling demonstration;
7. (7) an approved quality assurance and quality control plan must address all aspects of the demonstration; and,
8. (8) any additional criteria required by the commission.
(j) Not less than 120 days before expiration of the approved monitoring period under this section, the storage operator shall either apply to the commission for an additional monitoring period, or for a certificate of completion under AS 41.06.170 and 20 AAC 25.1320.