20241107_ADI Response - Mine Maps_61-19

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LEGEND:
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PERMIT BOUNDARY
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o PROPOSED HAUL ROADS
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`' d. FEMA FLOOD HAZARD LIMIT
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SEDIMENTATION AND STORMWATER
RIP RAP INLET PROTECTION PONDS — PROPOSED
W/ FILTER FABRIC LINER INV. = 2550.60
w OU TFALL LOCATION
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Q DA-1 BASIN
5040
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SKIMMER BASIN SK-1
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CHANNEL C-1 : n,.
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g 4.33'(W) X 1.4' (D) (3:1 SIDE SLOPES)
DRAINAGE AREA: 6.92 AC
z STRAW W/NET LINER
INV. - 2550.60M
PEAK FLOW(10-YR STORM): 16.42 CFS
m . t,_. ., ,. ._§ REQUIRED VOLUME: 12,456 CF
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REQUIRED SURFACE AREA: 5,337 SF
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PROVIDED VOLUME. 29,700 CF
"" :.o.._ PROVIDED SURFACE AREA: 8,400 SF
o RIP RAP INLET PROTECTION : { w TOP WIDTH: 40 FT
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o W/ FILTER FABRIC LINER BOTTOM WIDTH: 10 FT
Z TOP LENGTH: 210 FT
4t` JUTE NET BAFFLES (TYP. OF 3)
8 BOTTOM LENGTH: 180 FT
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SIDE SLOPES(Z:1): 2.5:1
c�'o MAIN BASIN OVERFLOW WEIR WIDTH: 16 FT
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04 OVERFLOW WEIR DEPTH: 1.5 FT
CHANNEL C-2:
EMERGENCY BYPASS SPILLWAY .. , `` -- OVERFLOW WEIR LINER MATL.: STRAW W/NET
16'(W) X 1.5' (D) (3:1 SIDE SLOPES) °, SKIMMER SIZE: 3 IN
a STRAW W/NET LINER OUTFALL 01 SKIMMER ORIFICE: 2.25 IN
INV. = 2550.60 DEWATERING TIME: 2.13 DAYS
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SOURCE:
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CL 1. BASEMAP COORDINATE SPACE IS NORTH CAROLINA STATE
w PLANE, NAD83 (NC83F).
3" FAIRCLOTH SKIMMER 3 2. PARCEL DATA PROVIDED BY MITCHELL COUNTY, NC83F,
0- w/2.25" ORIFICE PLATE 8 PUBLISHED APRIL 2021.
w 3. SURVEY FILE PROVIDED BY MOUNTAINEER LAND SURVEYING.
85 LF - 4" SCH. 40 4. AERIAL PROVIDED BY 2021 MICROSOFT CORPORATION,
PVC @ 1% SLOPE (min.) DISTRIBUTION AIRBUS DS 2021 .
a 5. GROUND SURFACE CONTOURS ARE BASED ON LOCAL ELEVATION
DATUM AND ARE APPROXIMATE.
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Z 0 30' 60'
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W N ;. GRAPHIC SCALE
LAND QUALITY
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F- MINING PROGRAM
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BUECHEL STONE CORPORATION
W Ir W STEEL GRAY' MINE
co � Z SPRUCE PINE, MITCHELL COUNTY, NORTH CAROLINA
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N PROPOSED EROSION AND
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U SEDIMENTATION BASINS
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EFIGURE
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NOTES: Construction 1. Clear, grub, and strip the area under the embankment of all vegetation and
° Specifications root mat. Remove all surface soil containing high amounts of organic matter
a DIETENTIO NP-ALLOW THE MAXIMUM REASONABLE and stockpile or dispose of it properly. Haul all objectionable material to the
DETENTION PERIOD BEFORE THE BASIN IS
COMPLETELY DEWATERED(AT LEAST 48 HOURS). designated disposal area. Place temporary sediment control measures below
' a INFLOW RATE-REDUCE THE INFLOW VELOCITY AND
W basin as needed
DIVERT ALL SEDIMENT-FREE RUNOFF.
Q 2. Ensure that fill material for the embankment is free of roots, woody
w vegetation, organic matter, and other objectionable material. Place the fill in
J lifts not to exceed 9 inches,and machine compact it. Over fill the embankment •The baffle material needs to be secured at the bottom and sides using
Plan View
6 inches to allow for settlement. staples.
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a ., 3. Shape the basin to the specified dimensions. Prevent the skimming device •Most of the sediment will accumulate in the first bay,so this should be
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from settling into the mud by excavating a shallow pit under the skimmer or readily accessible for maintenance.
I providing a low support under the skimmer of stone or timber.
Inflow x Y 4. Place the barrel (typically 4-inch Schedule 40 PVC pipe)on a firm, smooth
W structure 6
d d foundation of impervious soil. Do not use pervious material such as sand
w �( Extend 9 gauge wire to basin side or in"IT-post to anchor
W w gravel, or crushed stone as backfill around the pipe. Place the fill material Drape baffle material over strand and baffle to side of basin and secure to vertical post
around the pipe spillway in 4-inch layers and compact it under and around secure with plastic ties at posts and on wire every 12"
the pipe to at least the same density as the adjacent embankment. Care must 4'Max.-_O�
v be taken not to raise the pipe from the firm contact with its foundation whenow
compacting under the pipe haunches.
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cc h t� '��;� � 9 Gauge Min High
�� Place a minimum depth of 2 feet of compacted backfill over the pipe spillway Tension Wire Strand 3"MIN i6 Variable Depth
�` r }>� {� Emergency before crossing it with construction equipment. In no case should the pipe Shall Be Secured
spillway M�'ry l ' �x conduit be installed by cutting a trench through the dam after the embankment To Post To Support
N MOII'M '
k� � '° is complete. Baffle Material ; ; I Secure bottom of baffle to ground with
Averse _ Area
* I ; ; .____., 12*staples at 12'maximum spacing.
5. Assemble the skimmer following the manufacturers instructions, or as
0 Width W L �'� b Baffle Material
¢ designed.
U Baffle Material
¢ Area of basin water surface at Baffles 6. Lay the assembled skimmer on the bottom of the basin with the flexible /
top of principal spillway elevation
B joint at the inlet of the barrel pipe. Attach the flexible joint to the barrel pipe
N and position the skimmer over the excavated pit or support. Be sure to attach *If the temporary sediment basin will be 11 Gauge
o a rope to the skimmer and anchor it to the side of the basin. This will be used converted to a permanent stormwater basin Landscaping Staple
M to pull the skimmer to the side for maintenance. of greater depth,the baffle height should be
c14 Embankment
I'Freeboard Inflow Baffles 1 7. Earthen spillways—Install the spillway in undisturbed soil to the greatest based on the pool depth during use as a +
temporary sediment basin.
astructure
extent possible. The achievement of planned elevations, grade, design width, 1 i 1 and entrance and exit channel slopes are critical to the successful operation
> Dewa eri A of the spillway. The spillway should be lined with laminated plastic or Note:Install three(3)coir fiber baffles in basins �Steel Post
G. min:`iriver elevation of
zone emergency spillway impermeable geotextile fabric. The fabric must be wide and long enough to at drainage outlets with a spacing of 1l4 the 2- Depth
00 Emergency cover the bottom and sides and extend onto the top of the dam for anchoring basin length.Two(2)coir fiber baffles can be - -+
Filter fabric s iliwa installed in the basins less than 2U ft.in length Baffle Material should be secured to the bottom
p y in a trench. The edges may be secured with 8-inch staples or pins. The fabric g and sides of basin using 12"landscape staples
must be long enough to extend down the sloe and exit onto stable round. with a spacing of 1/3 the basin length.
O Sediment b g p g
Cross-Section
g storage zone View The width of the fabric must be one piece, not joined or spliced; otherwise
water can get under the fabric. If the length of the fabric is insufficient for the
3 entire length of the spillway, multiple sections, spanning the complete width,
may be used. The upper section(s) should overlap the lower section(s) so
J that water cannot flow under the fabric. Secure the upper edge and sides
W !CROSS SECTION OF SEDIMENT BASIN WITH SKIMMER OUTLET of the fabric in a trench with staples or pins. (Adapted from "A Manual for COIR FIBER BAFFLE DETAIL CROSS SECTION OF A POROUS
,AND EMERGENCY SPILLWAY Designing„Installing and Maintaining Skimmer Sediment Basins. February, BAFFLE IN A SEDIMENT BASIN
z 1999. J. W. Faircloth& Son.). 2
� N.T.S. N.T.S.
8. Inlets—Discharge water into the basin in a manner to prevent erosion. Use
otemporary slope drains or diversions with outlet protection to divert sediment-
laden water to the upper end of the pool area to improve basin trap efficiency
0 (References: Runoff Control Measures and Outlet Protection).
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9. Erosion control—Construct the structure so that the disturbed area is
c minimized. Divert surface water away from bare areas. Complete the
oembankment before the area is cleared. Stabilize the emergency spillway
co embankment and all other disturbed areas above the crest of theprincipal
cam,. spillway immediately after construction(References: Surface Stabilization).
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WATER ENTRY UNIT 10. Install porous baffles as specified in Practice 6.65,Porous Baffles.
W WITH TRASH SCREEN GENERAL NOTES:
1. PROPER DESIGN MUST BE COMPLETED TO MINIMIZE PIPING AROUND DISCHARGE 11. After all the sediment-producing areas have been permanently stabilized,
a PIPE.2. PROPER ORIFICE OPENING MUST BE SELECTED TO ENSURE POND DRAINS IN remove the structure and all the unstable sediment. Smooth the area to
C CORRECT AMOUNT OF TIME. MODIFICATIONS MAY BE REQUIRED IF (FIELD blend with the adjoining areas and stabilize properly (References: Sur face
CONDITIONS WARRANT A CHANGE.
0 3. EMBANKMENT MUST BE COMPACTED TO DESIGN SPECIFICATIONS. Stabilization).
U 4. EMERGENCY SPILLWAY MUST BE CORRECTLY SIZED AND EROSION PROTECTION
s ORIFICE OPENING INSIDE THE INSTALLED.
IZONTAL TUBE WITH A 5. EROSION PROTECTION MUST BE INSTALLED ALONG THE EMBANKMENT AND AT THE
OR
o DISCHARGE END OF THE PIPE. Maintenance Inspect skimmer sediment basins at least weekly and after each significant
CONSTANT HYDRAULIC HEAD 6. INSPECT SYSTEM REGULARLY TO ENSURE IT IS FUNCTIONING IN A CORRECT (one-half inch or greater) rainfall event and repair immediately. Remove
W MANNER,
Z 7. EIGHT SIZES OF SKIMMERS ARE AVAILABLE, REFER TO THE FLOW SHEET, CUT sediment and restore the basin to its original dimensions when sediment
SHEET, AND INSTRUCTIONS ON WEB SITE FOR EACH SIZE.
W accumulates to one-half the height of the first baffle. Pull the skimmer to
U SCHEDULE 40 PVC PIPE
one side so that the sediment underneath it can be excavated. Excavate the
(BARREL OR ARM)
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Q, sediment from the entire basin, not just around the skimmer or the first cell.
co Make sure vegetation growing in the bottom of the basin does not hold down
07
W the skimmer.
IX LEXIBLE HOSE ARTHEN EMBANKMENT
q FLOAT MERGENCY SPILLWAY PVC VENT Repair the baffles if they are damaged. Re-anchor the baffles if water is
OPIPE flowing underneath or around them.
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o If the skimmer is clogged with trash and there is water in the basin, usually
SCHEDULE 40 PVC PIPE LOAT
W TOP VIEW (BARREL OR ARM) jerking on the rope will make the skimmer bob up and down and dislodge
q
VC VENT PIPE the debris and restore flow. If this does not work, pull the skinumer over to wrz
w o FLEXIBLE HOSE the side of the basin and remove the debris. Also check the orifice inside the
0O w skimmer to see if it is clogged; if so remove the debris.
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in
J 3 = POTENTIAL FOR PIPING CAN = If the skimmer arm or barrel pipe is clogged, the orifice can be reunoved and W OCCUR. PROPER DESIGN PANING PROGP.M.1
_ F- E TO MINIMIZE DISCHARGE the obstruction cleared with a plumbers snake or by flushing with water. Be BUECHEL STONE CORPORATION
w iLi AROUND PIPE MUST OCCUR. sure and replace the orifice before repositioning the skimmer.
STEEL GRAY MINE
m, W Q L = 1.4 x: DEPTH SPRUCE PINE, MITCHELL COUNTY, NORTH CAROLINA
Cb zi Z Check the fabric lined spillway for damage and make any requited repairs
TO THE OVERFLOW
gW WATER ENTRY UNIT MINIMUM LENG11+1 APPLIES with fabric that spans the full width of the spillway. Check the embankment,
w O spillways, and outlet for erosion damage, and inspect the embankment for
w a — — _ = piping and settlement. Make all necessary repairs immediately. Remove all
o _ _ trash and other debris from the skimmer and pool areas. SEDIMENT AND EROSION CONTROL
o j_ � END VIEW DISCHARGE PIPE SIDE VIEW MAINTAIN DEPRESSION
CHANCE OF
000 &i LL SCHEDULE 40 (NO SCALE) SKIMMER BECOMING STUCK Freezing weather can result in ice forming in the basin. Some special DETAILS
VQ Q precautions should be taken in the winter to prevent the skimmer from
N 2 a plugging with ice.
o °J° FAIRCLOTH SKIMMER DISCHARGE SYSTEM WITH EMBANKMENT
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N.T.S. FIGURE
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