REP15039

• Permit No: C1981038
• IBM Index Class Name: Report
• Doc Date: 6/8/1992
• Doc Name: 1991 ANNUAL SUBSIDENCE REPORT
• Permit Index Doc Type: SUBSIDENCE REPORT
• Media Type: D
• Archive: No

previously established normal range of motion docimiented at
• this site.
Station 7: Surveys were initiated in August 1982 and continued biannually
through July 1984. Surveys were conducted once again in
November, 1987. Station 7 Overlies approximately 750 feet of
wert~urden. Zhe station showed no consistent indication of
subsidence effects thrwx~ 1987. 1991 survey results shag an
elevation gain of 1.41 feet evident since the last survey
(1987). Reference to Permit No. C-81-038, Map No. 2-2 shows
that station 7 lies in the general vicinity of a large mapped
landslide area. An evident change in eastirg coordinate
position may be ilrlicative of natural landslide movement
resulting in surficial material migrating wps-tward. The II
West Submains were advanced in the vicinity of station 7
during October, 1990. 'Ihe 1st North, 2 1/2 West area
approximately 300 feet south of station 7 was retreat mined
from May through June, 1983. No mining activity took place in
the immediate vicinity of station 7 during 1991.
Station 14: Station 14 is located in the Stevens Gulch alluvium protective
buffer zone over approximately 750 feet of Overburden. 'Ihe
station was initially surveyed in June, 1982. Subsequent
surveys were conducted annually since 1988. Data indicates
the station has seen an Overall increase in elevation
totalling 1.08 feet. Panel G was advanced under this station
• on September, 1988. Retreat mining occurred outside the
buffer zone adjacent to this site in February, 1989. An
elevation adjustment of -0.55 feet was detected at this site
in October, 1989 but was perhaps influenced by contxal station
coordinates being redefined. January 1991 data indicated 0.31
feet were subsequently gained but again, new control point
coordinates were generated. January 1992 data indicates 0.05
feet of elevation was lost over the last year. No further
mining activity took place in the vicinity of station 14
during 1991.
Station 15: Station 15 was newly established for the 1991 surveying year.
Station 15 Overlies approximately 700 feet of wert~urden and
is located within the 600 - 800 foot werixirden depth Stevens
C~ilch alluvium protective buffer zone. No mining activity has
taken place to date in the immediate vicinity of station 15.
Station 16: Station 16 overlies approximately 950 feet of wert~urden.
Surveys at station 16 were initiated in August, 1982 and
continued biannually through 1984. 'Ihe 1st North, 3 West
panel adjacent to and east of station 16 was retreat mined in
October, 1981. Panel A, located beneath station 16 was
retreat mined in July and August, 1991. 1991 survey data
indicates a 0.51 feet elevation gain at this site. Station 16
is located within a mapped landslide area as well. As with
station 7, Basting coordinates indicate surficial material is
• migrating westward at this location.
Station 88: Station 88 lies south of and adjacent to the II West Submain