ENFORCE29333

• Permit No: C1981039
• IBM Index Class Name: Enforcement
• Doc Date: 6/21/1992
• Doc Name: ROCKCASTLE CO GRASSY CREEK MINE PN C-81-039 RESPONSES TO PIT 4 ADEQUACY COMMENTS
• From: ACZ INC
• To: MLRD
• Violation No.: CV0000000
• Media Type: D
• Archive: No

• Rockcastle Company, Grassy Creek Mine Adequacy Responeses • 7
ADEQUACY RESPONSES
TO 11/22/91 CMLRD COMMENTS
JANUARY, 1992
METHODOLOGY CONCERNS
A) The use of a CN of 47 for undisturbed sagebmsh community is not justified by either the lrydrologic
soil classifications or the amount of cover found in llte baseline studies.
Response: Rockcastle concurs with [he Division. The hydrologic calculations for Pond 4 and
associated ditches which erroneously utilized a CN of 47 (10/16/91 Submittal) have been
superseded by [he revised calculations subsequently submitted in November, 1991.
B) 77te ]983 copy of "Soils of Colorado" lists the soil erodability value for the fop 12" of Rockcastle soils
as follows:
Coutis Fine Sandy Loant .20
~nevada - Splitro Complex .41/.18
Wiitevada Fine Sandy Loarn .41
Skylick .32
Mr. Nettleton has indicated in telephone conversations that the Rockcastle use of 0.24 is based on the
Rout County SCS revision of their soil erodability values. The Division needs to have published
verificatiwt of these values if dle consultant intends to use Utem wilt ony frequency.
Response: Curren[ SCS soil erodability values reflecting 1987 revisions were previously provided
a[ [he Division's request. A copy of [he SCS information accompanies these responses for the
Division' use and reference.
C) The reclmnatiort seed mix differed slig/ttly front the proposed seed mix in that a number of forbs were
dropped from the list and art extraordinarily large quantity of winter rye was added. It was noted that
t)te forbs w/tic)t were dropped had a contparative[y higher cost. Winter rye was apparerttlydnll-seeded
at a rate of 27 p/s/acre while al! other species cotttbirted were applied at 18 pls/acre. Winter rye cart
be a competitive threat to the establishment of a diversified stand of perennials. Staff" vegetation
specialists surest t)tat the rise of this quantity of winter rye is marginally acceploble witltoti!
employment of haying prior to [)te setting of seeds.
Response: Reclamation seeding was consistent with [he proposed permanent reclamation seed
mixture as defined by Table 6, Seed Mix #3 -Primary Reclamation, of the Rockcastle permit with
the exceptions of 0.5 Ibs pls/acre each of western yarrow and silver lupine. Seeding rates for the
other forbs noted on Table 6 are specified as "Trace" since these species are commonly present in
small quantities in the seed mixtures distributed in this area. Miscellaneous [race components are
identified in the seed analysis as "crop" since they are a relatively small percentage of the total and
are typically undesignated relative to species. Yarrow was not included in the mix due to limited
local availability, lupine was excluded due [o potential livestock toxicity, and winter rye was added
as a mulch crop [o achieve rapid vegetative establishment, protecting available topsoil resources
until other species can become well established.
ACZ Inc. ' P.O. Box 774018 'Steamboat Springs, Colorado 80477 • [phone]