2013-11-12_REVISION - C1981014 - Laserfiche WebLink

Home Browse Search

EFCI RESPONSES: DAVID BERRY'S "ADDITIONAL DETAILS" REQUEST PER LETTER OF 18 OCT, 2013: Concern 1. Please provide sample methodology and data compilation that meets Rule 4.15.11. Please assure that data compilation methods are statistically valid. ECFI may wish to refer to the Division's Guideline Regarding Selected Coal Mine Bond Release Issues, April 181995, for an example of combining data from more than one reference area. It is suggested that the revised page can be edited to clarify that an area- weighted average will be utilized. Response: The proposed vegetation sample methodologies are found on Permit page 2.05.4 -26 for cover and shrub density. The approved production sampling methodology is found on Permit page 2.05.4 -27. TR -39 does not do anything to change these approved sampling methodologies. Hence, the use of the weighted average approach is already approved in the permit document. With respect to the "area- weighted average" approach, Permit page 2.05.4 -27 specifically states that the data from Reference Plot A (Refuse Pile RA) and Reference Plot B (old PJ Woodland RA) "will be combined using a weighted average approach." The approved permit then states "Consistent with pre - disturbance vegetation boundaries and disturbed area mapping, the weighting factor will reflect 79.8 percent grassland and 20.2 percent ponderosa/pinion /juniper woodland disturbed." A careful review of the on -line laser fische file on the CDRMS website fails to document where these percentages were obtained. Evidence suggests that they were taken from the SCS Vegetation Report prepared in 1979, which would no longer be valid based upon changes in the disturbance limits. A comparison of the acreages found in the 2013 Annual Reclamation Report Reclamation Map, fails to confirm anything similar to these calculations. Accordingly, we have prepared current, more detailed estimates of the reclamation areas associated with the Southfield Mine. These calculations are found in revised Map 1, Southfield Mine - Reclamation Map, (used within the confines of TR -39) which has been revised from the Southfield Mine - Portal Reclamation Map, with minor modifications which was submitted in connection with the TR -39 application package. According to the GPS surveyed areas surveyed in September 2013, wherein we walked, or examined the detailed 2009 USDA photography and determined the boundaries of all of the reclaimed areas, including those associated with the Magpie Creek Diversion, the Refuse Pile diversion ditches and Sed Pond 4, along with numerous SAE areas which are typically not included in the revegetation "sampling universe," but which according page 9 of the Bond Release Guideline, "should be included in the vegetation sampling "universe" for bond release purposes..." The areas obtained from this sampling effort show that the area of revegetation at the Refuse Pile is 46.38 acres and the size of the Vento Portal reclamation is 21.93 acres of which 11.71 acres corresponds to the Corley Portal reclamation and 10.22 acres correspond to the Vento Portal reclamation area. According to these calculations, the total reclaimed acreage is 68.31 acres. The comments made in the CDRMS letter (Oct 18, 2013) about "the acreage of the two woodland reference areas is unequal" [sic] appears to be misplaced as they relate to the Southfield Mine. According to page 16 of the Bond Release Guideline it states that "an acreage- weighted sample mean is calculated from the entire bond release block, based upon the individual stratum sample means and their associated acreages." Example 2, found on pages 23- 24 of the Bond Release Guideline demonstrates how "the cover data for the bond release block was derived from acreage- weighting sampling within two separate reclamation parcels." One reclamation parcel containing 40 acres and the other containing 11 acres. Example 3, found on pages 24- 25 of the Bond Release Guideline, demonstrates how cover from two different reclaimed parcels is compared with three different vegetation types with different RA's. In this example, the weighted average is calculated on the acreage of the three disturbed vegetation types,