C502 EC details

Definition
Planting rapid -growing annual grasses, small grains, or legumes to provide
initial, temporary cover for erosion control on disturbed areas.
Purpose
To temporarily stabilize denuded areas that will not be brought to final grade
for a period of more than 21 calendar days.
Temporary seeding controls runoffand erosion until permanent vegetation or
other erosion control measures can be established. In addition, it provides
residue for soil protection and seedbed preparation, and reduces problems of
road and dust production from bare soil surfaces during construction,
Conditions Where
On any cleared, unvegetated, or sparsely vegetated soil surface where
Applies
vegetative etahve cover is needed for less than I year. Applications of this practice
include diversions, dams, temporary sediment basins, temporary road banks.
and topsoil stockpiles.
Planning
Annual plants, which sprout and grow rapidly and survive for only one season.
Considerations
are suitable for establishing initial or temporary vegetative cover. Temporary
seeding preserves the integrityof earthen sediment control structures such
as dikes, diversions, and the banks of dams and sediment basins. It can also
reduce the amount of maintenanceassociated with these devices. For example,
the frequency of sediment basin cleanouts will be reduced if watershed areas,
outside the active construction zone, are stabilized.
Proper seedbed preparation, selection of appropriate species, and use of quality
seed are as important in this Practice as in Practice 6.1 I , Permanent Seeding.
Failure to follow established guidelines and recommendations care£lly may
result in an inadequate or short-lived stand of vegetation that will not control
erosion.
Temporary seeding provides protection for no more than i year, during which
time permanent stabilization should be initiated.
Specifications
Complete grading before preparing seedbeds, and install all necessary erosion
control practices such as, dikes, waterways, and basins. Minimize steep slopes
because they make seedbed preparation difficult and increase the erosion
hazard. if soils become compacted during grading, loosen them to a depth of
6-8 inches using a ripper, harrow, or chisel plow.
SEEDBED PREPARATION
Good seedbed preparation is essential to successful plant establishment. A
good seedbed is welt -pulverized, loose, and unif'onn. Where hydroseeding
methods are used, the surface may be left with amore irregular surface of
large clods and stones.
Liming -Apply lime according to soil test recommendations. Ifthe pH (acidity)
of the soil is not known, an application of ground agricultural limestone at the
rate of I to 1 1/2 tons/acre on coarse -textured soils and 2-3 tons/acre on fine -
textured soils is usually sufficient. Apply limestone uniformly and incorporate
into the top 4-6 inches of soil. Soils with a pH of 6 or higher need not be
limed.
Fertilizer -Base application rates on soil tests. When these are not possible,
apply a 10-10-10 grade fertilizer at 700-1,000 lb/acre. Both fertilizer and time
should be incorporated into the top 4-6 inches of soil. if a hydraulic seeder is
used, do not mix seed and fertilizer more than 30 minutes before application.
Surface roughening -If recent tillage operations have resulted in a loose
surface, additional roughening may not be required, except to break up large
clods. if rainfall causes the surface to become sealed or crusted, loosen it
,just prior to seeding by disking, raking, harrowing, or other suitable methods.
Groove or furrow slopes steeper than 3:1 on the contour before seeding
(Practice 6.03, Surface Roughening).
PLANT SELECTION
Select an appropriate species or species mixture from Table 6.1 Oa for seeding
in late winter and early spring, Table 6.1 Ob for summer, and Table 6.1 Oc for
fall.
In fine Mountains, December and January secdings have pool- chances of
success. When it is necessary to plant at these times, use recommendations
for fall and a securely tacked mulch.
SEEDING
Evenly apply seed using a cyclone seeder (broadcast), drill, cultipacker seeder,
or hydrosceder. Use seeding rates given in Tables 6.1Oa-6.IOc, Broadcast
seeding and hydrosceding are appropriate for steep slopes where equipment
cannot be driven, Hand broadcasting is not recommended because of the
difficulty in achieving a uniform distribution.
Small grains should be planted no more than 1 inch deep, and grasses and
legumes no more than 1/2 inch. Broadcast seed must be covered by raking
or chain dragging, and then lightly firmed with a roller or cultipacker,
Hydroseeded mixtures should include a wood fiber (cellulose) mulch.
MULCHING
The use of all appropriate mulch will help ensure establishment under normal
conditions, and is essential to seeding success under harsh site conditions
(Practice 6.14, Mulching). Harsh site conditions include:
• seeding in fall for winter cover (wood fiber mulches are not considered
adequate for this use),
• slopes steeper than 3: 1,
• excessively hot or dry weather,
• adverse soils (shallow, rocky, or high in clay or sand), and
• areas receiving concentrated flow.
If the area to be mulched is subject to concentrated waterflow, as in channels,
anchor mulch with netting (Practice 6.14, Mulching).
Maintenance
Reseed and mulch areas where seedling emergence is poor, or where erosion
occurs, as soon as possible. Do not mow. Protect from traffic as much as
possible.
References
Site Preparation
6.03, Surface Roughening
6.04, Topsoiling
Su7f ice Stabilization
6.11, Permanent Seeding
6.14, Mulching
Appendix
8.02, Vegetation Tables
TEMPORARY SEEDING DETAIL
Table 6.10a
Temporary Seeding
p ry 9
Recommendations for Late
Winter and Early Spring
Table 6.10b
Temporary Seeding
Recommendations for
Summer
Table 6.10c
Temporary Seeding
Recommendations for Fail
Seeding mixture
Rate Species (lb/acre)
p
Rye (grain) 120
Annual lespedeza (Kobe in
Piedmont and Coastal Plain,
Korean in Mountains) 50
Omit annual lespedeza when duration of temporary cover is not to
extend beyond June.
Seeding dates
Mountains -Above 2500 feet: Feb. 15 - May 15
Below 2500 feet: Feb. 1- May 1
Piedmont -Jan. 1 - May 1
Coastal Plain -Dec. 1 -Apr. 15
Soil amendments
Follow recommendations of soil tests or apply 2,000 lb/acre ground
agricultural limestone and 750 lb/acre 10-10-10 fertilizer.
Mulch
Apply 4,000 lb/acre straw. Anchor straw by tacking with asphalt, netting,
or a mulch anchoring tool. A disk with blades set nearly straight can be
used as a mulch anchoring tool.
Maintenance
Refertilize if growth is not fully adequate. Reseed, refertilize and mulch
immediately following erosion or other damage.
Seeding mixture
Species Rate (lb/acre)
German millet 40
In the Piedmont and Mountains, a small -stemmed Sudangrass may be
substituted at a rate of 50 lb/acre.
Seeding dates
Mountains -May 15 -Aug. 15
Piedmont -May 1 -Aug. 15
Coastal Plain -Apr. 15 -Aug. 15
Soil amendments
Follow recommendations of soil tests or apply 2,000 Ib/acre ground
agricultural limestone and 750 lb/acre 10-10-10 fertilizer.
Mulch
Apply 4,000 lb/acre straw. Anchor straw by tacking with asphalt, netting,
or a mulch anchoring tool. A disk with blades set nearly straight can be
used as a mulch anchoring tool.
Maintenance
Refertilize if growth is not fully adequate. Reseed, refertilize and mulch
immediately following erosion or other damage.
Seeding mixture
Species Rate (lb/acre)
Rye (grain) 120
Seeding dates
Mountains -Aug. 15 - Dec. 15
Coastal Plain and Piedmont -Aug. 15 - Dec. 30
Soil amendments
Follow soil tests or apply 2,000 lb/acre ground agricultural limestone
and 1,000 lb/acre 10-10-10 fertilizer.
Mulch
Apply 4,00o lb/acre straw. Anchorstraw by tacking with asphalt, netting,
or a mulch anchoring tool. A disk with blades set nearly straight can be
used as a mulch anchoring tool.
Maintenance
Repair and refertilize damaged areas immediately. Topdress with 50
lb/acre of nitrogen in March. If it is necessary to extent temporary
cover beyond June 15, overseed with 50 lb/acre Kobe (Piedmont and
Coastal Plain) or Korean (Mountains) lespedeza in late February or
early March.
NOTES
1. STRUCTURAL STONE SHALL BE
CLASS B STDBR
2. SEDIMENT CONTROL STONE
SHALL BE NO, 6 OR NO, 57
STONE.
3, DIMENSIONS ARE MINIMUM
ACCEPTABLE UNLESS OTHERWISE
SPECIFIED BY THE ENGINEER,
STRUCTURAL STONE
FLOOD STORAGE ZONE
SEDIMENT STORAGE ZON
NATURAL GROUND
E OW
PIPE MAX
SEDIMENT CONTROL STONE_/ SECTION A -A
ANDARD ROCK PIPE INLET PROTECTION
CONSTRUCTIDN SPECIFICATIONS:
1. REMOVE AND PROPERLY DISPOSE OF ALL TREES, BRUSH, STUMPS AND OTHER OBJECTIONABLE
MATERIAL
2. ENSURE THAT THE MINIMUM CONSTRUCTED CROSS SECTION MEETS ALL DESIGN REQUIREMENT
3, ENSURE THAT THE TOP OF THE DIKE IS NOT LOWER AT ANY POINT THAN THE DESIGN ELEVATION
PLUS THE SPECIFIED SETTLEMENT.
4, PROVIDE SUFFICIENT BOOM AROUND DIVERSIONS IO PERMIT MACHINE REGRADING AND
CLEANOUT.
5, VEGETATE THE RIDGE IMMEDIATELY AFTER CONSTRUCTION, UNLESS IT WILL REMAIN IN PLACE
LESS THEN 30 WORKING DAYS.
MAINTENANCE
INSPECT TEMPORARY DIVERSIONS ONCE A WEEK AND AFTER EVERY RAINFALL, IMMEDIATELY
REMOVE SEDIMENT FROM THE FLOW AREA AND REPAIR 714E DIVERS1014 RIDGE. CAREFULLY
CHECK OUTLETS AND MAKE TIMELY REPAIRS AS NEEDED, WHEN THE AREA PROTECTED IS
PERMANENTLY STABILIZED, REMOVE THE RIDGE AND THE CHANNEL TO TURN WITH THE NATURAL
GROUND LEVEL AND APPROPRIATELY STABILIZE IT.
TEMPORARY DIVERSION DITCH
DEFINFRON: POROUS BARRIERS INSTALLED INSIDE A TEMPORARY SEDIMENT TRAP, SKIMMER BASIN, OR SEDIMENT BASIN TO REDUCE
THE VELOCITY AND TURBULENCE OF THE WATER FLOWING THROUGH THE MEASURE, AND TO FACILITATE THE SETTLING OF SEDIMENT
FROM THE WATER BEFORE DISCHARGE.
SEDIMENT TRAPS AND BASINS ARE DESIGNED TO TEMPORARILY POOL RUNOFF WATER TO ALLOW SEDIMENT TO SETTLE
BE�FORE THE WATER IS DISCHARGED. UNFORTUNATELY, THEY ARE USUALLY NOT VERY EFFICIENT DUE TO HIGH TURBULENCE AND
"SHORT-CIRCUITING" FLOWS WHICH TAKE RUNOFF QUICKLY TO THE OUTLET WITH LITTLE INTERACTION WITH MOST OF THE BASIN.
POROUS BAFFLES IMPROVE THE RATE OF SEDIMENT RETENTION BY DISTRIBUTING THE FLOW AND REDUCING TURBULENCE. THIS
PROCESS CAN IMPROVE SEDIMENT RETENTION.
CONDITIONS WHERE PRACTICE APPLIES THIS PRACTICE SHOULD BE USED IN ANY TEMPORARY SEDIMENT TRAP, SKIMMER BASIN, OR
TEMPORARY SEDIMENT BASIN.
PLANNING CONSIDERATIONS: POROUS BAFFLES EFFECTIVELY SPREAD THE FLOW ACROSS THE ENTIRE WIDTH OF A SEDIMENT BASIN OR
TRAP. WATER FLOWS THROUGH THE BAFFLE MATERIAL, BUT IS SLOWED SUFFICIENTLY TO BACK UP THE FLOW, CAUSING IT TO SPREAD
ACROSS THE ENTIRE WIDTH OF THE BAFFLE. SPREADING THE FLOW IN THIS MANNER UTILIZES THE FULL CROSS SECTION OF THE
BASIN, WHICH IN TURN REDUCES FLOW RATES OR VELOCITY AS MUCH AS POSSIBLE. IN ADDITION, THE TURBULENCE IS ALSO
GREATLY REDUCED. THIS COMBINATION INCREASES SEDIMENT DEPOSITION AND RETENTION AND ALSO DECREASES THE PARTICLE SIZE
OF SEDIMENT CAPTURED. THE INSTALLATION SHOULD BE SIMILAR TO A SEDIMENT FENCE. THE FABRIC SHOULD BE 700 G/M2 COIR
EROSION BLANKET OR EQUAL A SUPPORT WIRE ACROSS THE TOP WILL HELP PREVENT EXCESSIVE SAGGING IF THE MATERIAL IS
ATTACHED TO IT WITH APPROPRIATE TIES.
DESIGN CRITERIA: THE TEMPORARY SEDIMENT TRAP OR TEMPORARY SEDIMENT BASIN SHOULD BE SIZED USING THE APPROPRIATE
DESIGN CRITERIA. THE PERCENT OF SURFACE AREA FOR. EACH SECTION OF THE BAFFLE IS AS FOLLOWS:
• INLET ZONE - 25%
• FIRST CELL - 25%
• SECOND CELL - 25%
• OUTI-ET ZONE - 25%
BAFFLE SPACING IN FUTURE PERMANENT STORMWATER BASINS IS BEYOND FOREBAY. BE SURE TO CONSTRUCT BAFFLES UP THE
SIDES OF THE TRAP OR BASIN BANKS SO WATER DOES NOT FLOW AROUND THE STRUCTURES. MOST OF THE SEDIMENT WILL BE
CAPTURED IN THE INLET ZONE. SMALLER PARTICLE SIZE SEDIMENTS ARE CAPTURED IN THE LATTER CELLS, BE SURE TO MAINTAIN
ACCESS TO THE TRAP FCR MAINTENANCE AND SEDIMENT REMOVAL THE DESIGN UFE OF THE FABRIC IS 6-12 MONTHS, BUT MAY
NEED TO BE REPLACED MORE OFTEN IF DAMAGED OR CLOGGED.
CONSTRUCTION SPECIFICATIONS:
MATERALS
1. USE MATTING MADE OF 100% COCONUT FIBER (COIR) TWINE WOVEN INTO HIGH STRENGTH MATRIX WITH THE PROPERTIES SHOWN
IN THE TABLE BELOW.
2. STAPLES SHOULD BE MADE OF 0.125 INCH DIAMETER NEW STEEL WIRE FORMED INTO A •U' SHAPE NOT LESS THAN 12 INCHES
IN LENGTH WITH A THROAT OF 1 INCH IN WIDTH. :THE STAPLES ANCHOR THE POROUS BAFFLES INTO THE SIDES AND BOTTOM
OF THE BASIN.
3. ENSURE THAT STEEL POSTS FOR POROUS BAFFLES ARE OF A SUFFICIENT HEIGHT TO SUPPORT BAFFLES AT DESIRED HEIGHT.
POSTS SHOULD BE APPROXIMATELY 1-3/8' WIDE MEASURED PARALLEL TO THE FENCE, AND HAVE A MINIMUM WEIGHT OF 1.25
LB/LINEAR FT. THE POSTS MUST BE EQUIPPED WITH AN ANCHOR PLATE HAVING A MINIMUM AREA OF 14.0 SQUARE INCHES AND
BE OF THE SELF -FASTENER ANGLE STEEL TYPE TO HAVE A MEANS OF RETAINING WIRE AND COIR FIBER MAT IN THE DESIRED
POSITION WITHOUT EMPLACEMENT.
4. USE 9-GAUGE HIGH TENSION WIRE FOR SUPPORT WIRE.
COIR FIBER BAFFLE MATERIAL PROPERTY REQUIREMENTS
THICKNESS
0.30 IN. MINIMUM
TENSILE STRENGTH (WET)
90OX680 LB/FT MINIMUM
ELONGATION (WET)
69% X 34% MAXIMUM
LOW VELOCITY
10-12 FT/SEC
WEIGHT
20 OZ/SY (680 G/M� MINIMUM
MINIMUM WIDTH
6.5 FEET
OPEN AREA
50% MAXIMUM
CONSTRUCTION
1. GRADE THE BASIN SO THAT THE BOTTOM IS LEVEL FROM TO BACK AND SIDE TO SIDE.
2. INSTALL THE COIR FIBER BAFFLES IMMEDIATELY UPON EXCAVATION OF THE BASINS.
3. INSTALL POSTS ACROSS THE WIDTH OF THE SEDIMENT TRAP (PRACTICE 6.62, SEDIMENT FENCE)
4. STEEL POSTS SHOULD BE DRIVEN TO A DEPTH OF 24 INCHES. AND SPACED A MAXIMUM OF 4 FEET APART. THE TOP OF THE
FABRIC SHOULD BE A MINIMUM OF 6 INCHES HIGHER THAN THE INVERT OF THE SPILLWAY. TOPS OF BAFFLES SHOULD BE A
MINIMUM OF 2 INCHES LOWER THAN THE TOP OF THE EARTHEN EMBANKMENT.
5. INSTALL AT LEAST THREE ROWS OF BAFFLES BETWEEN THE INLET AND OUTLET DISCHARGE POINT. BASINS LESS THAN 20 FEET
IN LENGTH MAY USE 2 BAFFLES.
6. ATTACH A 9 GAUGE HIGH TENSION WIRE STRAND TO THE STEEL POSTS AT A HEIGHT OF 6 INCHES ABOVE THE SPILLWAY
ELEVATION WITH PLASTIC TIES OR WIRE FASTENERS TO PREVENT SAGGING. IF THE TEMPORARY SEDIMENT BASIN WILL BE
CONVERTED TO A PERMANENT STORMWATER BASIN OF A GREATER DEPTH, THE BAFFLE HEIGHT SHOULD BE BASED ON THE POLL
DEPTH DURING USE A TEMPORARY SEDIMENT BASIN.
7. EXTEND 9 GAUGE MNIMUM HIGH TENSION WIRE STRAND 0 SIDE OF BASIN OR INSTALL STEEL T-POSTS TO ANCHOR BAFFLE TO
SIDE OF BASIN AND SECURE TO VERTICAL END POSTS.
B. DRAPE THE COIR FIBER MAT OVER THE WIRE STRAND MOUNTED AT A HEIGHT OF 6 INCHES ABOVE THE SPILLWAY ELEVATION.
SECURE THE COIR FIBER MAT TO THE WIRE STRAND WITH PLASTIC TIES OR WIRE FASTENERS. ANCHOR THE MATTING TO THE
SIDES AND FLOOR OF THE BASIN WITH 12 INCHES WIRE STAPLES, APPROXIMATELY 1 FT APART, ALONG THE BOTTOM AND SIDE
SLOPES OF THE BASIN.
9. DO NOT SPLICE THE FABRIC, BUT USE A CONTINUOUS PIECE ACROSS THE BASIN
10. ADJUSTMENTS MAY BE REQUIRED IN THE STAPLING REQUIREMENTS TO FIT INDIVIDUAL SITE CONDITIONS.
MAINTENANCE: INSPECT RIFFLES AT LEAST ONCE A WEEK AND AFTER EACH RAINFALL MAKE ANY REQUIRED REPAIRS IMMEDIATELY. BE
SURE TO MAINTAIN ACCESS TO MAINTAIN ACCESS TO THE BAFFLES. SHOULD THE FABRIC OF A BAFFLE COLLAPSE, TEAR, DECOMPOSE,
OR BECOME INEFFECTIVE, REPLACE IT PROMPTLY. REMOVE SEDIMENT DEPOSITS WHEN IT REACHES HALF FULL, TO PROVIDE ADEQUATE
STORAGE VOLUME FOR THE NEXT RAIN AND TO REDUCE PRESSURE ON THE BAFFLES. TAKE CARE TO AVOID DAMAGING THE BAFFLES
DURING CLEANOUT, AND REPLACE IF DAMAGED DURING CLEANOUT OPERATIONS. SEDIMENT DEPTH SHOULD NEVER EXCEED HALF THE
DESIGNED STORAGE DEPTH. AFTER THE CONTRIBUTING DRAINAGE AREA HAS BEEN PROPERLY STABILIZED, REMOVE ALL BAFFLE
MATERIALS AND UNSTABLE SEDIMENT DEPOSITS, BRING THE AREA TO GRADE, AND STABILIZE IT.
/ B `POROUS BAFFLES
G502
CONSTRUCTION 3PECRICATIONS
12°MIN. WASHED
--'TOP OF DAM
1.CLEAR, GRUB AND STRIP THE AREA UNDER THE EMBANKMENT OF ALL VEGETATION
STONE FILTER
5'MIN, 70POFWEIR
AND ROOT MOT. REMOVE. ALL SURFACE SOIL CONTAINING HIGH AMOUNTS OF
NWOT STD.#57
ORGANIC AWTER AND STOCKPILE OR DISPOSE OF IT PROPERLY. PAUL ALL
3600 CU. FT./ACRE
.5'
T
OBJECTIONABLE MATERIAL TO THE DESIGNATED DISPOSAL AREA.
5'FMA%.
2, ENSURE THAT FILL MATERIAL FOR THE EMBANKMENT IS FREE OF ROOTS, WOODY
SEDIMENTTRAP R1 I
Z, FILL
VGULINIIUIV JItUN\YIL LMIICII ftL1UUlULIt UUJ[LIIULIftULL ,nNiCI11flL. Y1J\LL
��..��pp��
THE FILL III THIS NOT TO EXCEED 9-INCHES AND MACHINE COMPACT IT. OVERALL
THE EMBANKMENT 6-INCHES TO ALLOW FOR SETTLEMENT.
COARSEST ONE FILL
3, CONSTRUCTME OUTLET SECTION In THE EMBANKMENT. PROTECT THE CONNECTION
CRASS R EROSION
ROSIOSIONE
HLTEfl FABRIC
SETANEEN TFHF RIPRAP AND THE SOIL FROM PIPING DY USING FILTER FABRIC OR A
CLASSA
KEYWAY CUTMFF TRENCH BETWEEN THE RIPRAP STRUCTURE AND THE SOIL
CROSS SECTION
a. PLACE THi FILTER FABRIC BETWEEN THE RIPRAP AND SOIL EXTEND THE FABRIC
ACROSS THE SPILLWAY FOUNDATION AND SIDES TO THE TOP OF THE DAM;
OR
OVERFILL 6. FOR EMERGENCY BY-PASS 6'
b, EXCAVATE A KEYWAY TRENCH ALONG THECENTERLINE OFTHE SPILLWAY
DESIGN
SETTLEMENT BELOW SETTLED TOP
FOUNDATON EXTENDING UP THE SIDES TO THE HEIGHT OF THE DAM. THE WENCH
SETTLED
211N
OFDAM
SHOULD BE AT LEAST&FEET DEEP AND&FEET WIDE WITH I:I SIDE SLOPES.
TOP
5'
1.51-
4, CLEAR THE NBC AREA BELOW THE ELEVATION OF THE CREST OF THE EMBANKMENT.
I
5. ALL CUT ANDFILL SLOPES SHOULD BE 21 OR FLATTER.
SM
6, ENSURE THAT THE STONE (DRAINAGE) SECTION OF THE EMBANKMENT FURS A MINIMUM
Fl L
NATURAL
BOTTOM WIDTH OF 3-FEET AND MAXIMUM SIDE SLOPES OF 1:1 THAT EXTEND TO THE
_
GROUND
BOTTOM OF TIE SPILLWAY SECTION,
3'
7. CONSTRUCT -HE MINIMUM FINISHED STONE SPILLWAY BOTTOM WIDTH, AS SHOWN ON
21 SIDE
IN.
THEPLANSWITH2A SIDE SLOPES EXTENDING TO THE TOP OF THE OVERFILLED
ALTER
SLOPE MAX.
EMBANKMER. KEEP THE THICKNESS OF THE SIDES OF THE SPILLWAY OUTLET STRUCTURE
FABRIC
is SLOE
AT A MIMMUM OF 21 INCHES THE WEIR MUST BE LEVEL AND CONSTRUCTED TO GRADE
SLOPE MAX.
TO ASSURE DESIGN CAPACITY. STONE SECTION
B. MATERIAL UDEO IN THE STONE SECTION SHOULD BE WELL -GRADED MIXTURE OF STONE
WAR A d50 SZE OF 9- INCHES (CLASS B EROSION CONTROL STONE IS RECOMMENDED) MAINTENANCE
AND A FMAtlhUM STONE SIZE OF 14-INCHES. THE STONE MAY BE MACHINE PLACED
ADD THE SMILLER STONES WORKED INTO THE VOIDS OF THE LARGER STONES. THE 1. INSPECT TEMPORARY SEDIMENT TRAPS AFTER EACH PERIOD OF SIGNIFICANT
STONE SHOUD BE HARD, ANGULAR, AND HIGHLY WEATHER -RESISTANT' RAINFALL, REMOVE SEDIMENT AND RESTORE THE TRAP TO ITS ORIGINAL DIMENSIONS
9, ENSURE THAI THE STONE SPILLWAY OUTLET SECTION EXTENDS DOWNSTREAM PAST THE WHEN THE SEDIMENT HAS ACCUMULATED TO THE -HALF THE DESIGN DEPTH OF THE
TOE OF THE EMBANKMENT UNTIL STABLE CONDITIONS ARE REACHED AND OUTLET TRAP PLACE THE SEDIMENT THAT 13 REMOVED IN THE DESIGNATED DISPOSAL AREA
VELOCITY IS N3CEPTABLE FOR THE RECEIVING STREAM. KEEP THE EDGES OF THE STONE AND REPLACE THE CONTAMINATED PART OF THE GRAVEL FACING.
OUTLET SECTON FLUSH WITH THE SURROUNDING GROUND AND SHAPE THE CENTER TO 2 CHECK THE STRUCTURE FOR DAMAGE FROM EROSION OR PIPING. PERIODICALLY
CONFINE THEOUTFLOW STREAM (REFERENCES: OUTLET PROTECTION). CHECK THE DEPTH OF THE SPILLWAY TO ENSURE IT IS A MINIMUM OF 1.5 r. BELOW
10, DIRECT EMERGENCY BYPASS TO NATURAL, STABLE AREAS. LOCATE BYPASS OUTLETS THE LOW POINT OF THE EMBANKMENT. IMMEDIATELY ALL ANY SETTLEMENT OF THE
SO THAT nW WILL NOT DAMAGE THE EMBANKMENT. EMBANKMENT TO SLIGHTLY ABOVE DESIGN GRADE. ANY RIPRAP DISPLACED FROM
11. STABILIZE TIE EMBANKMENT AND ALL DISTURBED AREAS ABOVE. 711E SEDIMENT POOL THE SPILLWAYtMUST BE REPLACED IMMEDIATELY.
AND DOWNSTREAM FROM THE TRAP IMMEDIATELY AFTER CONSTRUCTION 3. AFTER ALI.SEDIMENT-PRODUCING AREAS HAVE BEEN PERMANENTLY STABILIZED.
(REFERENCE: SURFACE STABILIZATION). REMOVE 711E STRUCTURE AND ALL UNSTABLE SEDIMENT, SMOOTH THE AREA TO
12. SHOW THE DSTANCE FROM THE TOP OF THE SPILLWAY TO THE SEDIMENT CLEANOUT BLEND WITH THE ADJOINING AREAS AND STABILIZE PROPERLY (REFERENCES!
LEVEL(ONE-4ALF THE DESIGN DEPTH) ON THE PLANS AND MARK IT IN THE FIELD. SURFACE STABILIZATION.
TEMPORARY SEDIMENT TRAP
WOVE]
GENERAL NOTES
MNNTENANCENOTES:
1. SEDIMENT FILTER OUTLET SHALL BE 16 INCHES HIGH BUT NO
1, FILTER OUTLETS SHALL BE INSPECTED BY THE FINANCIALLY
TALLER THAN 18 INCHES
RESPONSIBLE PARTY OR HIS AGENT IMMEDIATELY AFTER
EACH RAINFALL AND AT LEAST DALY DURING PROLONGED
2, CRASS I OR 2 RIP -RAP SHALL BE USED AND COVERED WITH
RAINFALL. ANY REPAIRS NEEDED SHALL BE MADE
61NCHES OF NOBOT 05 OR*57 WASHED STONE ON THE
IMMEDIATELY,
UPSLOPE SIDE
2. THE STONE SHALL BE REPLACED PROMPTYARTER ANY
3. POSTS SHALL BE NO MORE THAN 4 FEET APART.
EVENT THAT RAS CLOGGED OR REMOVED T.
4. SITE OUTLETS AT ANY POINT SMALL CONCENTRATED FLOWS
3. SEDIMENT DEPOSITS SHOULD BE REMOVED WHEN
ARE ANTICIPATED AND AT THE DIRECTION OF THE
DEPOSITS REACH HALF THE HEIGHT OF THE BARRIER ANY
INSPECTOR,
SEDIMENT DEPOSITS REMANDING IN PLACE AFTER THE SILT
FENCE OUTLET IS REMOVED SHALL BE DRESSED TO
5, ONE ACRE tMM14UM DRAINAGE AREA PER OUTLET.
CONFORM TONE DUSTING GRACE, PREPARED AND
SEEDED,
ILT FENCE STONE OUTLET
SECTION
STEEL POST
CLASSIOR2 I'MIN WASHEDSTONE
RIP -RAP (NCDOT 05 OR N57)
ow
M1RR a xAlawx aom un w®
DRAG A DRNWBD AD1M M
R110lYt CGC1� „N,o„oo„<x,nn.
PLAN
#57 WASHED STONE & WIRE INLET PROTECTION
NOTE;
BASIN DESIGN
. SEE PROJECT EROSION CONTROL PLAN FOR SPECIFIC BASIN DIMENSIONS AND ORIENTATION
WATER LEVEL ELEV Z
5-9
m
m
TYPICAL BASIN PLAN
FLOATING SURFACE
MIN.
TOP OF DAM
SKIMMER SEE DETAIL
§
E
ELEVATION
2
-`EMERGENCY
Iv
SUPPORT ROPE OR SUPPORT POST STAKE TO
BAFFLE 2 1
SPILLWAY WIRE TO PREVENT 2V INTO BOTTOM SUPPORTWIRE
ELEVATION SAGGING 08810E
BASIN BOTTOM ELEVATION
COMPACTEDEARTH
_
EMBANKMENT STABILIZED
CHILE.
' PARTIAL BASIN SECTION PROTECTION
CONSTRUCTION SPECIFICATIONS
Coln SIMILAR
STAPLED T
TRENCHED
BAFFLE ELEVATION STAPLEDDORENCHER
i. CLEAR, GRUB, AND STRIP THE AREA UNDER THE EMBANKMENT OFALL VEGETATION AND
INTO BOTTOM OR SIDE
HOOT MAT. REMOVE ALL SURFACE SOIL CONTAINING HIGH AMOUNTS OF ORGANIC
CONSTRUCTION SPECIFICATION
MATTER AND STOCKPILE OR DISPOSE OF IT PROPERLY. HAUL ALL OBJECTIONABLE MATERIAL
TO THE DESIGNATED DISPOSAL AREA, PLACE TEMPORARY SEDIMENT CONTROL MEASURES
1. GRADE THE BASIN SO THE BOTTOM IS LEVEL FRONT TO BACK AND SIDE TO SIDE.
BELOW BASIN AS NEEDED.
2. INSTALL POST ACROSS THE WIDTH OF THE SEDIMENT TRAP (PRACTICE 662, SEDIMENT FENCE)
3, STEEL POST SHOULD BE DRIVEN TO A DEPTH OF 24 INCHEGSPACED A MAXIMUM OF 4 FEET
2. ENSURE THAT FILL MATERIAL FOR THE EMBANKMENT IS FREE OF ROOTS, WOODY VEGETATION,
APART, AND INSTALLED UP THE SIDES OF THE BASIN AS WELL THE TOP OF THE FABRIC SHOULD
ORGANIC MATTER, AND OTHER OBJECTIONABLE MATERIAL. PLACE THE FILL IN LIFTS NOT TO
BE 6 INCHES HIGHER THAN THE INVERT OF THE SPILLWAY. TOPS OF BAFFLES SHOULD BE 2 INCHES
EXCEED 9INCHES, AND MACHINE COMPACT IT. OVER FILL THE EMBANKMENT 6 INCHES TO
LOWER THAN THE TOP OF THE BERMS.
ALLOW FOR SETTLEMENT.
4, INSTALL AT LEAST THREE ROWS OF BAFFLES BETWEEN THE AND THE OUTLET POINT. BASINS
LESS THAN 20 FEET IN LENGTH MAY USE 2 BAFFLER. `
3. SHAPE THE BASIN TO THE SPECIFIED DIMENSIONS. PREVENT THE SKIMMING DEVICE FROM
5, WHEN USING POST, ADD A SUPPORT WIRE OR ROPE ACROSS THE TOP OF THE MEASURE TO
SETTLING INTO THE MUD BY EXCAVATING A SHALLOW PIT UNDER THE SKIMMER OR
PREVENT SAGGING,
OR PROVIDING A LOW SUPPORT UNDER THE SKIMMER OF STONE OR BLOCK.
6, WRAP POROUS MATERIAL, LIKE JUTE BACKED BY COIN MATERIAL, OVER THE TOP WIRE. 711E FABRIC
SHOULD HAVE FIVE TO TEN PERCENT OPENINGS IN THE WEAVE. ATTACH FABRIC TO A ROPE AND
4. PLACE THE BARREL (TYPICALLY 4-INCH SCHEDULE 40 PVC PIPE) ON A ANN, SMOOTH
SUPPORT STRUCTURE WITH ZIP TIES, WIRE, OR STAPLES.
FOUNDATION OF IMPERVIOUS SOIL DO NOT USE PERVIOUS MATERIAL SUCH AS SAND,
7. THE BOTTOM AND SIDES OF THE FABRIC SHOULD BE ANCHORED IN A TRENCH OR PINNED WITH
GRAVEL, OR CRUSIIED STONE AS BACKFILL AROUND THE PIPE. PLACE THE FILL MATERIAL
8 INCH EROSION CONTROL MATTING STAPLES.
AROUND THE PIPE SPILLWAY IN 4-INCH LAYERS AND COMPACT IT UNDER AND AROUND
8, DO NOT SPLICE THE FABRIC, BUT USE A CONTINUOUS PIECE ACROSS THE BASIN.
THE PIPE TO AT LEAST THE SAME DENSITY AS THE ADJACENT EMBANKMENT. CARE MUST BE
TAKEN NOT TO RAISE THE PIPE FROM THE FIRM CONTACT WITH ITS FOUNDATION WHEN
MAINTENANCE
COMPACTING UNDER THE PIPE HAUNCHES.
PLACE A MINIMUM DEPTH OF 2 FEET OF COMPACTED BACKFILL OVER THE PIPE SPILLWAY
INSPECT BAFFLES AT LEAST ONCE A WEEK AND AFTER EACH RAINFALL, MAKE ANY REQUIRED REPAIRS
BEFORE CROSSING IT WITH CONSTRUCTION EQUIPMENT. IN NO CASE SHOULD THE PIPE
IMMEDIATELY.
CONDUIT BE INSTALLED BY CUTTING A TRENCH THROUGH THE DAM AFTER THE EMBANKMENT
IS COMPLETE.
BE SURE TO MAINTAIN ACCESS TO THE BAFFLES. SHOULD THE FABRIC OF A BAFFLE COLLAPSE, TEAR,
DECOMPOSE, OR BECOME INEFFECTIVE, REPLACE IT PROMPTLY.
5. ASSEMBLE THE SKIMMER FOLLOWING THE MANUFACTURERS INSTRUCTIONS, OR AS DESIGNED.
REMOVE SEDIMENT DEPOSITS WHEN IT REACHES HALF FULL TO PROVIDE ADEQUATE STORAGE
6, LAY THE ASSEMBLED SKIMMER ON THE BOTTOM OF THE BASIN WITH THE FLEXIBLE JOINT AT THE
VOLUME FOR THE NEXT RAIN AND TO REDUCE PRESSURE ON THE BAFFLES.
INLET OF THE BARREL PIPE, ATTACH THE FLEXIBLE JOINT TO THE BARREL PIPE AND POSITION THE
SKIMMER OVER THE EXCAVATED PIT OR SUPPORT, BE SURE TO ATTACH A ROPE TO THE SKIMMER
AFT ER THE CONTRIBUTING DRAINAGE AREA HAS BEEN PROPERLY STABILIZED, REMOVE ALL BAFFLE
AND ANCHOR IT TO THE SIDE OF THE BASIN. THIS WILL BE USED TO PULL THE SKIMMER TO THE
MATERIALS AND UNSTABLE SEDIMENT DEPOSITS, BRING THE AREA TO GRADE, AND STABILIZE IT.
SIDE FOR MAINTENANCE.
Sediment Basin Baffle
7, EARTH EN SPILLWAYS- INSTALL THE SPILLWAY IN UNDISTURBED SOIL TO THE GREATEST EXTENT
POSSIBLE. THE ACHIEVEMENT OF PLANNED ELEVATIONS, GRADE, DESIGN WIDTH, AND
ENTRANCE AND EXIT CHANNEL SLOPES ARE CRITICAL TO THE SUCCESSFUL OPERATION OF
G' IDSCIH.OAT 40 SKIMMER
THE SPILLWAY. THE PILLWAY SHOULD BE LINED WITH LAMINATED PLASTIC OR IMPERMEABLE
PVC PIPE FL
INFLUENT
GEOTWILE FABRIC. THE FABRIC MUST BE WIDE AND LONG ENOUGH TO COVER THE BOTTOM
6• PVC By
AND SIDES AND EXTEND ONTO TIE TOP OF THE DAM FOR ANCHORING IN A TRENCH. THE
BEND TYP.
EDGES MAY BE SECURED WITH B-INCH STAPLES OR PINS. 711E FABRIC MUST BE LONG ENOUGH
TO EXTEND DOWN THE SLOPE AND EXIT ONTO STABLE GROUND. THE WIDTH OF THE FABRIC
MUST BE ONE PIECE HOT JOINED OR SPLICED' OTHERWISE WATER CAN GET UNDER THE FABRIC.
IF THE LENGTH OF THE FABRIC IS INSUFFICIENT FOR THE ENTIRE LENGTH OF THE SPILLWAY,
SHOULD OVERLAPTHELOWER SECHON(S) SO THAT WATER CANNOT FLOW UNDER THE FABRIC.
4' PVC VENT 4°x4°TEE
SECURE THE UPPER EDGE AND SIDES OF THE FABRIC IN A TRENCH WITH STAPLES OR PINS.
8. INLETS - DISCHARGE WATER INTO THE BASIN IN A MANNER TO PREVENT EROSION. USE
TEMPORARY SLOPE DRAINS OR DIVERSIONS WITH OUTLET PR07ECTION TO DIVERT SEDIMENT
`q
LADEN WATER TO THE UPPER END OF THE POOL AREA TO IMPROVE BASIN TRAP EFFICIENCY.
9. EROSION CONTROL- CONSTRUCT THE STRUCTURE SO THAT THE DISTURBED AREA IS MINIMIZED,
DIVERT SURFACE WATER AWAY FROM BARE AREAS. COMPLETE THE EMBANKMENT BEFORE
FLOWCONTROL
GALVANIZED STL
THE AREA IS CLEARED. STABILIZE THE EMERGENCY SPILLWAY EMBANKMENT AND ALL OTHER
ORIFICE
STRAP TYPICAL
DISTURBED AREAS ABOVE THE CREST OF THE PRINCIPAL SPILLWAY IMMEDIATELY AFTER
CONSTRUCTION.
4-
° D. SCR. 4O
10. INSTALL POROUS BAFFLES AS INDICATED IN SEDIMENT BASIN BAFFLE DETAIL.
11. PRODUCING AREAS HAVE BEEN STABILIZED, REMOVE
THE STRUCTUREANDAN THE
THE AREA
THE AREA TO BLEND WITH THE
OTH THE
WING STABILUNSTAOLESEDIMEM.SMOOTH
ADJOINING AREAS AND STABILIZE PROPERLY,
SKIMMER
W PVC CAP
INFLUENT
-6
MAINTENANCE1
5-U'
INSPECT SKIMMER SEDIMENT BASINS AT LEAST WEEKLY AND AFTER EACH SIGNIFICANT (ONE-HALF
INCH OR GREATER) RAINFALL EVENT AND REPAIR IMMEDIATELY. REMOVE SEDIMENT AND RESTORE
SKIMMER PLAN
THE BASIN TO ITS ORIGINAL DIMENSIONS WHEN SEDIMENT ACCUMULATES TO ONE-HALF THE
HEIGHT OF THE FIRST BAFFLE, PULL THE SKIMMER TO ONE SIDE SO THAT THE SEDIMENT UNDERNEATH
6° LD. SCH, 40
IT CAN BE EXCAVATED. EXCAVATE THE SEDIMENT FROM THE ENTIRE BASIN, HOT JUST AROUND THE
4°PVCVENT PVC PIPE FLOAT
SKIMMER OR THE FIRST CELL. MAKE SURE VEGETATION GROWING IN THE BOTTOM OF THE BASIN
DOES NOT HOLD DOWN THE SKIMMER.
REPAIR THE BAFFLES IF THEY ARE DAMAGED. RE -ANCHOR THE BAFFLES IF WATER IS FUNDS
UNDERNEATH OR AROUND THEM.
IF THE SKIMMER IS CLOGGED WITH TRASH AND THERE IS WATER IN THE BASIN, USUALLY JERKING
4° 2ZS BEND
ON THE ROPE WILL MAKE THE SKIMMER BOB UP AND DOWN AND DISLODGE THE DEBRIS AND
SP x HUB
RESTORE FLOW. IF THIS DOES NOT WORK, PULL THE SKIMMER OVER TO THE SIDE OF THE BASIN
4°PVC TEE
AND REMOVE THE DEBRIS. ALSO CHECK THE ORIFICE INSIDE THE SKIMMER TO SEE IF IT IS
HOSE
STNSTL. HOSE 4°xA-PVC TEE
STN.STLCLAMPS
CLOGGED; IF SO REMOVE THE DEBRIS,
4° PVC FLANGE
IF THE SKIMMER ARM OR BARREL PIPE IS CLOGGED, THE ORIFICE CAN BE REMOVED AND THE
4°FLEXIBLE
OBSTRUCTION CLEARED WITH A PLUMBERS SNAKE OR BY FLUSHING WIN WATER BE SURE AND
HOSE
REPLACE THE ORIFICE BEFORE REPOSITIONING THE SKIMMER,
3°LD.SC11. 40 nOWCOOTH ORIFICE
PVC PIPE CUT CI
CHECK THE FABRIC LINED SPILLWAY FOR DAMAGE AND MAKE ANY REQUIRED REPAIRS WITH
OPENING TO DIMENSION
INGTOHC DIMENSION
FABRIC THAT SPANS THE HULL WIDTH OF THE SPILLWAY. CHECK THE EMBANKMENT, SPILLWAYS,
INDICATED ON BASIN SITE
AND OUTLET FOR EROSION DAMAGE, AND INSPECT THE EMBANKMENT FOR PIPING AND
BASIN BOTTOM PLAN
SETTLEMENT. MAKE ALL NECESSARY REPAIRS IMMEDIATELY. REMOVE ALL TRASH AND OTHER
DEBRIS FROM THE SKIMMER AND POOL AREAS.
SKIMMER ELEVATION
FREEZING WEATHER CAN RESULT IN ICE FORMING IN THE BASIN. SOME SPECIAL PRECAUTIONS
SHOULD BE TAKEN IN THE WINTER TO PREVENT THE SKIMMER FRONT PLUGG114G WITH ICE,
Floating Surface Skimmer
1 'SEDIMENT BASIN AND SKIMMER
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© 2019 LaBelle Associates
ALAMANCE
AGGREGATES,
rf Threatt, r
Snow Camp Mine
1
1/20/20
ADDITIONAL STREAM INFO - ALAM. AGE.
& LAND QUALITY COMMENTS
N0:
DATE:
DESCRIPTION:
REVISIONS
PROJECT NUMBER:
2190335
DRAWN BY:
KCG/ATC
REVIEWED BY:
PAS
ISSUED FOR:
CONSTRUCTION
DATE:
1 /23/20
DRAWING NAME:
WIM 1Wf
DETAILS
DRAWING NUMBER: