The U.S. Environmental Protection Agency has released final contractor reports assessing the structural integrity of scores of Coal Combustion Residuals impoundments and similar units, most of which are considered to have a high potential hazard rating.
The reports are part of EPA’s effort to evaluate the structural integrity of CCR surface impoundments as it weighs a proposed rule (75 FR 51434, Aug. 20, 2010) on the “Disposal of Coal Combustion Residuals from Electric Utilities.”
The proposed rule follows the failure of the CCR impoundment at the Tennessee Valley Authority’s Kingston facility in December 2008.
Data Collection, Hazard Potential
In 2009, EPA sent information collection requests to electric utilities that have surface impoundments or similar management units that contain CCRs.
All of the responses covering 228 facilities and 629 surface impoundments are posted in the docket for the proposed rule. The docket also includes reports and materials related to site assessments that EPA has conducted on a subset of these impoundments.
The 200 units in that subset have been given a hazard potential rating using the U.S. Army Corps of Engineers National Inventory of Dams criteria. Of the 200 units rated, 50 (25%) are rated as having a Significant Hazard Potential; 71 (36%) are rated as having a Low Hazard Potential; and 8 (4%) are rated as having a Less than Low Hazard Potential.
The ratings do not assess the stability of these units, EPA notes. Rather, they assess the potential for loss of life or environmental and economic damage. Units with a High Hazard Potential are those where failure will probably cause a loss of life.
Only impoundments rated “unsatisfactory” pose immediate safety threats, and none of the impoundments assessed so far have received an unsatisfactory rating.
EPA has provided a copy of the final report to each facility and has requested that it implement the recommendations in the reports and develop plans for taking action.
Limitations and Claims
EPA contractors were not authorized to conduct any physical drilling, coring or sampling while on site. Furthermore, some companies have claimed that certain information they provided is Confidential Business Information.
EPA has already denied some of these CBI claims. For claims still pending, the agency has redacted the information under appeal. If the claims are denied, the information will be added to EPA’s web site.
Of the 629 impoundments and units covered in these responses, 443 (70%) were designed by a professional engineer. The units show considerable variation in height, with 80 (13%) greater than 50 feet high; 133 (21%) between 25 and 51 feet; 268 (43%) between 6 and 26 feet; 39 (6%) between 0 and 7 feet high; and 105 (17%) with no height.
EPA’s assessments are continuing, but it is making the 53 final reports available for comment.
EPA is soliciting comments on the information, including the extent to which the responses and assessment materials should be factored into EPA’s final rule. Public comments on the proposed rule are due by Nov. 19.
The documents can be accessed on EPA’s site.