|
based on demand, of 270 days per year; 180 days for 80%of material shipped,and 90 days(shoulder months, Spring
<br /> and Fall,and extending into Winter)for the remaining 20%of material. This scheduling is strictly based on customer
<br /> demand: these periods are based on experience in Archuleta County and elsewhere. It is not possible to restrict
<br /> excavation, processing, and shipment to winter months, as there is little or no construction and maintenance done
<br /> during that time of year,weather can impact material quality,and more land would be required for stockpiles.
<br /> Initially, a portable plant will be deployed to the site for the processing season, moving from another location
<br /> and then redeploying to yet another location to produce materials. The owner and operator reserve the right to replace
<br /> the portable plant system to a plant located at Oakbrush Hill(permanently or with this location as a"home base"for a
<br /> portable plant to be deployed elsewhere). Even then,excavation and processing will not be a continuous activity. As
<br /> discussed in Exhibit M (Air Quality), plant capacity will determine the hours of operation to produce up to 72,000 tons
<br /> per year. Based on rated capacity, a 250-tph(ton per hour) plant will require 288 operating hours(36 8-hour days or
<br /> 29 10-hour days); a 400-tph plant will require 180 operating hours (22.5 8-hour or 18 10-hour days), and a 500-tph
<br /> plant will require 144 hours(18 8-hr or 14.410-hr days). However,certain types of construction materials require much
<br /> lower throughput (as low as 30-40 tph even for a 250-tph plant). Weather and frequent maintenance also limits
<br /> production time, so the actual season will be much longer. Crushing and screening will not be done on Sundays or
<br /> holidays or during hours of darkness, unless specifically approved by County agencies for exceptional conditions such
<br /> as urgent projects. (A fixed-location plant may reduce total traffic in/out somewhat.)
<br /> ASSUMPTIONS:
<br /> 1. Annual production will be variable, For planning purposes to produce and ship 72,000 tons per year, plus
<br /> materials for mining and ranching operations, it is assumed that excavation of up to 100,000 CY per year
<br /> (cypy)may be required. Actual amount produced and hauled from the operation will be based on demand,
<br /> not ability to produce.
<br /> 2. Screenings(fines and rejects)and clean material(construction&demolition debris and excavated dirt/rock
<br /> from project sites, if not processed as recycled construction materials)will be used for backfill and attaining
<br /> final grade.
<br /> 3. Soil(A and B horizon) ranges from 0.1 to 0.4 foot in depth, and averages 3 inches(0.25 feet). Soil,
<br /> including subsoil suitable for rooting zone use, and clean soil brought on-site from projects by customers will
<br /> be salvaged and used or stored for use in reclamation as work progresses.
<br /> 4. Overburden(fines,including clay,often with some organic content)varies significantly, but appears to
<br /> occupy the upper 3 feet of the excavation profile. Due to the nature of these alluvial(and potentially glacial)
<br /> deposits(especially landslide and colluvium),lenses of overburden are expected to be found throughout the
<br /> profile.Although some of this material may be sold and shipped off-site for use in backfill, most will be
<br /> stored and used to achieve final grades and slopes.
<br /> 5. Exposed profile from past operations provides good indications that depth of the alluvial deposits is about 20
<br /> feet but is expected to vary from point to point.The basement rock(various members of the Mancos shale)
<br /> is generally distinct from the deposits being mined,and excavation into the shale will be avoided except as
<br /> necessary to provide drainage and suitable terrain for placement of overburden and soil during reclamation.
<br /> 6. In some portions of the project,the alluvial deposits may be very thin above the shale, but this cannot be
<br /> quantified until stripping and excavation is done,or test pits are dug after permitted operations begin.
<br /> 7. All excavation will be above the water table. Storm water may accumulate in swales and basins, particularly
<br /> at the top of the shale, and may have to be pumped or discharged to swales cut to larger areas.This may
<br /> be necessary to prevent muddy operating conditions and to speed evaporation to meet the 72-hour State
<br /> Engineer requirement for retaining precipitation.There will be no surface discharge with less than a 100-
<br /> year storm event.
<br /> 8. Slopes for pit edges will be no greater than 2H:1 V and cut as mining progresses, in preference to reducing
<br /> highwalls to use that material for the final slope. Overburden will be the preferred and planned method of
<br /> meeting slope requirements. When possible, slope will be 3H:1 V and match nearby slopes.There may be
<br /> areas where pre-excavation slopes are steeper than 2:1,which will require review at the time of discovery
<br /> and may require slope stability evaluation by an engineer and possibly a technical revision.
<br /> 9. Pit floors will generally slope to the east and no surface discharge or retention basin (impoundment)is
<br /> planned. Ephemeral ponds may exist during mining, based on slopes,stages of mining, and control and
<br /> C&J Gravel Products, Inc. Page 15 of 93 20 OCT 2021
<br /> Application for Permit: Oakbrush Hill Gravel M-2021- C&J-DPR-V5-001
<br />
|