2020-07-06_REVISION - M1984041

• Permit No: M1984041
• IBM Index Class Name: REVISION
• Doc Date: 7/6/2020
• Doc Name: Request For Amendment To Permit
• From: American Gypsum Co.
• To: DRMS
• Type & Sequence: AM4
• Email Name: SJM
• Email Name: THM
• Media Type: D
• Archive: No

2019 Plan of Operations Modification American Gypsum Company, LLC
TABLE 1.2: PERMITTED AND ACTUAL SURFACE DISTURBANCE SUMMARY
Facility Disturbance (acres)
Existing Disturbance-BLM Permitted HI Actual'm Pem*Reference
e
Roads and Sediment Ponds P] 41.0 40.0 CO DNR, 1990; CO DRMS, 2003 (TR-06);
CO DRMS, 2006 JR-07)
Mine Office/Staging Area 131 5.6 2.1 CO DNR, 1990
Upper Pit 56.5 44.3 BLM, 2002; CO DRMS, 2001
Upper Pit Intraburden Stockpile 7.9 4.0 BLM, 2002; CO DRMS, 2001
Upper Pit 6900 Access Road 141 5.8 0.0 BLM, 2019; CO DRMS, 2019a JR-11)
Lower Pit Intraburden Stockpile 5.6 5.0 CO DNR, 1990; CO DRMS, 2017 JR-10)
Ore Stockpile 5.3 4.9 CO DNR, 1990
Old Mine 37.7 19.0 CO DNR, 1984
Total 165.4 119.3
Existing Disturbance-Private Permitted tat Actual 121 Permit Reference
Roads, Sediment Ponds, CO DNR, 1990; CO DRMS, 2003 JR-06);
Intraburden Stockpile, and 23.5 15.5 CO DRMS, 2006 (TR-07), CO DRMS, 2017
Mine Office/Staging Area 131 JR-10)
Lower Pit 58.5 56.7 CO DNR, 1990 and CO DRMS, 2017 JR-10)
Total 82.0 72.2
OTHER 151 6.6 N/A
TOTAL 254 191.5
Notes:
N Permitted disturbance includes disturbance areas within permit approvals(see Table 1.4).Tierra Group
digitized linework from maps where electronic data or permitted disturbance acreage was not available in
permit applications or approvals.
I2)Actual disturbance from American Gypsum,divided by land type(BLM-controlled vs private).
131 1990 permit documents did not separate roads, intraburden stockpile, and Mine Office within pit areas.
141 CO DRMS approval(CO DRMS, 2019a)lists total disturbance area as 5.8 acres. Reclamation grading was
revised(5.0 acres of post-reclamation disturbance area)at the request of BLM;drawings reflect 5.0-acre
disturbance area.
151 Tierra Group reviewed available permitting documents and was unable to account for the full 254 acres of
disturbance area reported by CO DRMS(CO DRMS,2019b).This discrepancy may be due to overlapping
areas between permit submittals,discrepancies in delineating disturbance areas from copies of maps,or other
missing information.American Gypsum does not anticipate additional disturbance outside what is shown on
Drawing 03 and Tables 1.2 and 1.3.
Tierra Group compared available permitted disturbance limit delineations with actual disturbance
limits (from the 2018 annual report (American Gypsum, 2018), with refinements based on aerial
imagery) and determined several discrepancies between permit limits and actual disturbance
limits, primarily for roads and sediment ponds. These discrepancies are likely due to inaccuracies
in delineating disturbance area limits from permit documents or incomplete historical records.
Table 1.2 shows that the actual disturbance acreage is less than the permitted acreage. For
completeness, Drawing 03 shows actual disturbance limits; American Gypsum does not
anticipate disturbing additional areas outside the areas shown on Drawing 03 and listed in
Tables 1.2 and 1.3.
Am Gypsum Poo Mod ISSD 20190909 September 2019 [41