2010-07-27_PERMIT FILE - M2009076 ‎(13)‎

• Permit No: M2009076
• IBM Index Class Name: PERMIT FILE
• Doc Date: 7/27/2010
• Doc Name: Adequacy Response- Stormwater Management Plan
• From: Venture Resources
• To: DRMS
• Email Name: ACS
• Media Type: D
• Archive: No

• o Mobile Construction Equipment: Any loaders, excavators, dump trucks, etc. shall be
well maintained and in proper working order to avoid unnecessary leaks of oil, coolant,
or any other fluids. Operators will be instructed to do a walk-around safety inspection to
identify problems at the start of each shift. Any maintenance may be performed within
the Crusher Feed Pile enclosure on the concrete pad not only for a better working
environment, but also to facilitate clean-up of accidental spills. There are no equipment
washing facilities.
o Housekeeping Trash: There will be rather insignificant generation of rubbish waste
associated with routine work habits of upto 6 full-time employees. Several 55 gal. drums
fitted with lids and trash bag liners will be located outside for trash receptacles. These
will be emptied as necessary and taken to the municipal trash disposal facility at the
Clear Creek County Transfer Station.
• Sediment and Erosion Prevention: "There will be several structural BMP's employed to collect
and contain sediment and prevent erosion. Additionally, several non-structural techniques will
also be implemented.
o Sediment Pond: Below the leachate collection structure (a facility regulated by the
DRMS permit M-2009-076) the perimeter diversion ditches enter a Sediment Pond to
settle out any sediments that may have been collected before final release. This structure
is designed to collect stormwater runoff from the Tailings Impoundment Affected Area
and allow any carried sediment a chance to settle for future removal. Sizing has been
done to allow for containment and settling of a 10 year/ 24-hour storm event (2.6" as
reported by NOAA Atlas 2, Vol. III) and controlled passage of a 100 year/ 24-hour storm
event (3.8" as reported by NOAA Atlas 2, Vol. III). During a 100 year/24-hour event, a
Peak Discharge into the Sedimentation Collection Pond will be produced in the amount
of +/- 20 cfs (9,000 gprn). The rip-rapped discharge weir (12' long) is more than capable
of passing this peak flow. At the 10 year/24-hour Peak Flow, the Sedimentation
Collection Pond discharge weir is designed to pass +/- 2.43 cfs (1,090 gpm), or 30%,
• during the one hour spike time. However, a storage volume of 0.13 acre-ft (42,000 gal.)
is provided for containment below the weir to give sufficient time for settling any
sediment. Periodically, any collected sediment shall be removed and disposed of in the
lined tailings impoundment.
o New Tailings Impoundment: As part of rigorous reclamation measures prescribed in
the DRMS permit M-2009-076, final grading and re-vegetation of the Tailings
Impoundment will be performed in phased increments. Permanent reclamation and
control measures will be installed in 10 feet phased increments (elevation height of one
quarter of a terrace) which is estimated to occur every several months. Seeding will
occur to coincide with the appropriate time of year for proper gen nination, whether it is
closer to spring or fall season. Additionally, as each 40' high terrace is completed, the
exposed surface of the terrace will be re-vegetated as described above.
o Biosolids/Topsoil Salvage Area:
¦ Within the Tailings Impoundment Area is a stockpile location for storing
recycled topsoil and Class A biosolids for augmenting soil. Silt fence shall be
installed around these piles to contain any possible sediment and erosion.
o Mobile Mill Area:
¦ The only processing equipment open to the weather is the crushing operation.
Downgradient from the 35' crushing trailer and related conveyors silt fence shall
be installed to prevent sediment and erosion. Operators will be trained to
monitor this silt fence and repair as needed,
c. Preventative Maintenance
• Stormwater Diversion: Periodic inspection of diversion ditches shall be performed to
insure that the structures have not been damaged or compromised. Any sediment collected
shall be removed as required. Any compromised rip-rap shall be repaired and/or replaced.
The Sediment Pond shall be inspected after each rain event and in the spring after the melt
to insure its integrity. Again, any collected sediment shall be removed. The weir structure
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