2012-08-21_REVISION - M1980244 (32)

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16. On page 12 -4 of Volume I, the Applicant has stated the application rate of the seed mix will be approximately 25 pounds of pure live seed (PLS) per acre. The proposed seeding rate is appropriate for drill seeding; however, the rate should be doubled for broadcast or hydroseeding. Please clarify if this is the seeding rate which is intended to be used for all three seeding application methods. RESPONSE: Prior amendment applications reviewed and approved for the Cresson Project have included this seeding mix rate and reclamation has been successful at CC &V at this seed rate. Recently published studies by practitioners of high altitude revegetation work in the Intermountain West, suggest historically that mine reclamation projects have used seeding rates which are too high. CC &V has followed this research effort and would respectfully request the Division approve the universal application of 25 Ibs /acre PLS regardless of method of application. The specific research papers cited in this response are as follows: (1) "Overburden Revegetation with Low Seeding Rates and Minimal Soil Amendments at Tyeras Limestone Quarry, NM" by Robin Bay, Ken Carlson, and Wayne Erickson —a paper presented at the High Altitude Revegetation Workshop in Ft. Collins, CO, March 2010 and (2) `Implications of Plant Density on the Resulting Community Structure of Mine Site Land" by L. Jefferson in Restoration Ecology, 200412(3), pages 429 -438. Additionally, drill seeding is not a normal seeding method due to general rocky conditions of the growth medium and CC &V's normal seeding rates are based on broadcast seeding or hydromulching methods. CC &V seeding rates are also more appropriately based on seed per square foot, which is generally in the range of 60 to 100 seeds per square foot. These seeding rates have proven effective in over 20 years of reclamation at the Cresson Project. 17. On page 12 -4 of Volume I, the Applicant has stated that broadcast and drill seeded areas will generally not be required to be mulched. Please explain why these areas will generally not be required to be mulched. RESPONSE. Mulching with straw and/or wood fiber hydromulch has been used by CC &V in previous reclamation projects dating to the early 1990's. While there has been success with mulch if the seeding was done on steep slopes (2.5H to 1 V) or if the seeding was done where tillage was not possible, the over- whelming evidence —based on experience at the site — indicates that good quality growth medium (fertile, not compacted, and well graded texture), seed -bed preparation (ripping, tracking with dozer cleats, and/or harrowing), and timing of seed application are the most important factors to achieving successful revegetation at the Cresson Project. Mulching can be effective in extremely dry years when it can be crimped and protected from wind -blown losses; however, this should be evaluated on a site -by -site basis. Generally, with adequate growth medium, effective tillage, and timely seed application, mulching will not be necessary on broadcast and drill- seeded areas. 18. The Applicant has stated seeding of grasses will occur primarily in the late spring/early summer and/or during the late fall/early winter periods. Please note that Indian ricegrass has a high rate of dormancy and germination may be improved by fall dormant planting. RESPONSE. CC &V has so noted that Indian ricegrass has a high rate of dormancy and germination and this may be improved by fall dormant planting. Indian ricegrass is not one of the dominant species in the seed mix and in fact has not shown great promise at the Cresson Project. With that said, it does have apotential benefit if conditions are right. The Division's concerns are well- taken. 19. The Applicant has provided an Alternate Species seed mix to be used in the event the species from the Preferred Species seed mix are not commercially available. The Division requests the Operator commit to notifying the Division in writing of any changes to the seed mix should any of the preferred species not be commercially available. The grass species on the Alternate Species list are non - native and the Division wants to ensure that if one or more species are replaced, that the seed mix contains a well rounded mix of grass species which is appropriate to the post - mining land use. RESPONSE: The seed mixes noted in the application may be revised due to availability, climate conditions, continued vegetation monitoring, specific site conditions, and/or general refinement of the revegetation methods. CC &V is committed to noting the Division in writing to changes to the seed mix.