SW6211204_Plansheet S-6 - Misc. Detail_20220216

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6" MIN. e
Nti
2-3" COURSE
AGGREGATE
EXISTING
SLOPE FOR VEHICULAR TRAFFIC
PAVEMENT
EDGE
MAINTAIN BERM & VALLEY
TO PREVENT SEDIMENT LADEN
/WATER
FROM LEAVING SITE
12"
10" i
24
6" MIN.
FILTER FABRIC
TEMPORARY CONSTRUCTION ENTRANCE
(NOT TO SCALE)
L = The distance such that points
A and B are of equal elevation
DESIGN CRITERIA
AGGREGATE SIZE - USE 2-3 INCH WASHED STONE.
DIMENSIONS OF GRAVEL PAD:
THICKNESS: 6 INCHES MINIMUM
WIDTH: 12-FEET MINIMUM OR FULL WIDTH AT ALL POINTS OF
THE VEHICULAR ENTRANCE AND EXIT
AREA WHICHEVER IF GREATER
LENGTH: 50-FEET MINIMUM
LOCATION - LOCATE CONSTRUCTION ENTRANCES AND EXITS TO LIMIT
SEDIMENT FROM LEAVING THE SITE AND TO PROVIDE FOR MAXIMUM
UTILITY BY ALL CONSTRUCTION VEHICLES. AVOID STEEP GRADES,
AND ENTRANCES AT CURVES IN PUBLIC ROADS.
WASHING - IF CONDITIONS AT THE SITE ARE SUCH THAT MOST OF THE
MUD AND SEDIMENT ARE NOT REMOVED BY VEHICLES TRAVELING
OVER THE GRAVEL, THE TIRES SHOULD BE WASHED. WASHING
SHOULD BE DONE ON AN AREA STABILIZED WITH CRUSHED STONE
THAT DRAINS INTO A SEDIMENT TRAP OR OTHER SUITABLE DISPOSAL
AREA. A WASH RACK MAY ALSO BE USED TO MAKE WASHING MORE
CONVENIENT AND EFFECTIVE.
CONSTRUCTION SPECIFICATIONS
1. CLEAR THE ENTRANCE AND EXIT AREA OF ALL VEGETATION,
ROOTS, AND OTHER OBJECTIONABLE MATERIAL AND PROPERLY
GRADE IT.
2. PLACE THE GRAVEL TO THE SPECIFIC GRADE AND DIMENSIONS
SHOWN ON THE PLANS, AND SMOOTH IT.
3. PROVIDE DRAINAGE TO CARRY WATER TO SEDIMENT TRAP OR
OTHER SUITABLE OUTLET.
4. USE GEOTEXTILE FABRICS BECAUSE THEY IMPROVE STABILITY
OF THE FOUNDATION IN LOCATIONS SUBJECT TO SEEPAGE OR HIGH
WATER TABLE.
MAINTAIN THE GRAVEL PAD IN A CONDITION TO PREVENT MUD OR
SEDIMENT FROM LEAVING THE CONSTRUCTION SITE. THIS MAY
REQUIRE PERIODIC TOPDRESSING WITH 2-INCH STONE. AFTER EACH
RAINFALL, INSPECT ANY STRUCUTRE USED TO TRAP SEDIMENT AND
CLEAN IT OUT AS NECESSARY. IMMEDIATELY REMOVE ALL
OBJECTIONABLE MATERIALS SPILLED, WASHED, OR TRACKED ONTO
PUBLIC ROADWAYS.
Figure 6.83a Space check dams in a channel so that the crest of downstream dam is at elevation of the toe of upstream dam.
Filte
Cross -Section View
CHECK DAM WITH WEIR
(NOT TO SCALE)
dl
Cross-Section
View
Firer
Steel fabric Backfill trench Natural
post and compact ground
, thoroughly
Upsbpe
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8
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MI.4'
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Flgum 6.e2a tns Nation doWit ofa aedimentfence.
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Rev. 6w6 6.62.5
SILT FENCE DETAIL
(NOT TO SCALE)
Inlet zone
25% of surface area
5'CrestWidth�
Inflow
Structure
Riprap
or Slope Drain
Earthen 11-10
embankment
with stabilized
side slopes
First Chamber Second Chamber
25%of surface area 25%of surface area
t IY fi I
CONSTRUCTION
1. PLACE STRUCTURAL STONE (CLASS B) TO THE LINES AND DIMENSIONS SHOWN ON THE PLAN ON A FILTER
Drape baffle material over wire strand and
FABRIC FOUNDATION. THE CREST WIDTH OF THE DAM SHOULD BE A MINIMUM OF 2 FEET.
2. KEEP THE CENTER STONE SECTION AT LEAST 9 INCHES BELOW THE END WHERE THE DAM ABUTS THE CHANNEL
secure with plastic ties at posts and on wire every 12'
BANKS.
3. PLACE SEDIMENT CONTROL STONE (#5 OR #57) ON THE UPSTREAM SIDE OF THE DAM THAT IS A MINIMUM OF 1
FOOT THICK.
4. PROVIDE AN APRON THAT IS 3 TIMES THE HEIGHT OF THE DAM. THE APRON WIDTH IS AT LEAST 4 FEET LONG.
UNDERCUT THE APRON SO THAT THE TOP OF THE APRON IS FLUSH WITH THE SURROUNDING GRADE.
5. EXTEND THE STONE AT LEAST 1.5 FEET BEYOND THE DITCH BANK TO KEEP WATER FROM CUTTING AROUND THE
ENDS OF THE CHECK DAM.
9 Gauge Min. High
6. EXCAVATE SEDIMENT STORAGE AREA TO THE DIMENSIONS SHOWN ON THE PLAN.
Tension Wire Strand±TM�IN.*7.
INSTALL 3 BAFFLES EVENLY SPACED IN SEDIMENT STORAGE AREAShall
Be Secured
To Post To Support
Baffle Material
MAINTENANCE
INSPECT CHECK DAMS AND CHANNELS AT LEAST WEEKLY AND AFTER EACH
SIGNIFICANT (2 INCH OR GREATER) RAINFALL EVENT AND REPAIR IMMEDIATELY.
CLEAN OUT SEDIMENT, STRAW, LIMBS, OR OTHER DEBRIS THAT COULD CLOG THE
CHANNEL WHEN NEEDED.
ANTICIPATE SUBMERGENCE AND DEPOSITION ABOVE THE CHECK DAM AND EROSION
FROM HIGH FLOWS AROUND THE EDGES OF THE DAM. CORRECT ALL DAMAGE
IMMEDIATELY. IF SIGNIFICANT EROSION OCCURS BETWEEN DAMS, ADDITIONAL
MEASURES CAN BE TAKEN SUCH AS, INSTALLING A PROTECTIVE RIPRAP LINER IN
THAT PORTION OF THE CHANNEL.
REMOVE SEDIMENT ACCUMULATED BEHIND THE DAMS AS NEEDED TO PREVENT
DAMAGE TO CHANNEL VEGETATION, ALLOW THE CHANNEL TO DRAIN THROUGH THE
STONE CHECK DAM, AND PREVENT LARGE FLOWS FROM CARRYING SEDIMENT OVER
THE DAM. ADD STONES TO DAM AS NEEDED TO MAINTAIN DESIGN HEIGHT AND
CROSS SECTION.
UPSTREAM END OF OVERFLOW
UPSTREAM END OF STORM DRAIN
STORM DRAIN
1/3 PIPE
a DIAMETER
a
3/4" EXTERIOR PLYWOOD
i°
3/4- EXTERIOR PLYWOOD
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=IIII 1 11 1 -' l
L-- III I- II
BURY BOTTOM
OF PLYWOOD PLYWOOD INLET PROTECTION NOTE:
ALL PARTIALLY COMPLETED STORM DRAINS, UP
TO 24" PIPE SIZE, SHALL BE PROTECTED AT
STEEL FENCE POST THE END OF EACH DAY IN ACCORDANCE WITH
TYPICAL UPSTREAM END OF THESE DETAILS.
STORM DRAIN
UPSTREAM END OF
II STORM DRAIN OVERFLOW
II II'
-III 1/3 PIPE
DIAMETER
11h ii ii IIII 111111 °
WASHED STONE FILTER
ACROSS PIPE INLET I111 d 4 ° ° WASHED STONE FILTER
I- ACROSS PIPE INLET
HARDWARE CLOTH „(IIII
I=111=III- 11=III- � I_I 11=111=111=III III
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STONE FILTER INLET PROTECTION
STANDARD PIPE INLET PROTECTION (PLYWOOD & STONE)
Baffle Material
• If the temporary sediment basin will be
converted to a permanent stormwater basin
of greater depth, the baffle height should be
based on the pool depth during use as a
temporary sediment basin.
Note: Install three (3) coir fiber baffles in basins
at drainage outlets with a spacing of 1 /4 the
basin length. Two (2) coir fiber baffles can be
installed in the basins less than 20 ft. in length
with a spacing of 1/3 the basin length.
POROUS BAFFLES DETAIL
(NOT TO SCALE)
RIP RAP APRON
J THICKNESS AS
PER PLAN
RIP RAP GRAVEL
SIZED & PLACED
AS PER PLAN
STORM PIPE
"'i
Baffles
4' Max.
FIGURE 6.65b
CONSTRUCTION
1. CONSTRUCT THE SEDIMENT BARRIER OF STANDARD STRENGTH OR EXTRA
STRENGTH SYNTHETIC FILTER FABRICS.
2. ENSURE THAT THE HEIGHT OF THE SEDIMENT FENCE DOES NOT EXCEED 24 INCHES ABOVE THE
GROUND SURFACE. (HIGHER FENCES MAY IMPOUND
VOLUMES OF WATER SUFFICIENT TO CAUSE FAILURE OF THE STRUCTURE)
J. CONSTRUCT THE FILTER FABRIC FROM A CONTINUOUS ROLL CUT TO THE LENGTH OF THE BARRIER
TO AVOID JOINTS. WHEN JOINTS ARE NECESSARY, SECURELY FASTEN THE FILTER CLOTH ONLY AT A
SUPPORT POST WITH 4 FEET MINIMUM OVERLAP TO THE NEXT POST.
4. SUPPORT STANDARD STRENGTH FILTER FABRIC BY WIRE MESH FASTENED SECURELY TO THE
UPSLOPE SIDE OF THE POSTS. EXTEND THE WIRE MESH SUPPORT TO THT BOTTOM OF THE TRENCH.
FASTEN THE WIRE REINFORCEMENT, THEN FABRIC ON THE UPSLOPE SIDE OF THE FENCE POST. WIRE
OR PLASTIC ZIP TIES SHOULD HAVE MINIMUM 50 POUND TENSILE STRENGTH.
5. WHEN A WIRE MESH SUPPORT FENCE IS USED, SPACE POSTS A MAXIMUM OF 8 FEET APART.
SUPPORT POSTS SHOULD BE DRIVEN SECURELY INTO THE GROUND A MINIMUM OF 24 INCHES.
6. EXTRA STRENGTH FILTER FABRIC WITH 6 FEET POST SPACING DOE NOT REQUIRE WIRE MESH
SUPPORT FENCE. SECURELY FASTEN THE FILTER FABRIC DIRECTLY TO POSTS. WIRE OR PLASTIC
ZIP TIES SHOULD HAVE MINIMUM 50 POUND TENSILE STRENGTH.
7. EXCA VA TE A TRENCH APPROXIMA TEL Y 4 INCHES WIDE AND 8 INCHES DEEP ALONG THE PROPOSED
LINE OF POSTS AND UPSLOPE FROM THE BARRIER (FIGURE 6.62a).
8. PLACE 12 INCHES OF THE FABRIC ALONG THE BOTTOM AND SIDE OF THE TRENCH.
9. BACKFILL THE TRENCH WITH SOIL PLACED OVER THE FILTER FABRIC AND COMPACT. THOROUGH
COMPACTION OF THE BACKFILL IS CRITICAL TO SILT FENCE PERFORMANCE.
10. DO NOT ATTACH FILTER FABRIC TO EXISTING TREES.
11. NO MEASURES ARE TO BE REMOVED UNTIL DENR APPROVAL.
INSTALLATION SPECIFICATIONS
1. THE BASE OF BOTH END POSTS SHOULD BE AT LEAST ONE FOOT HIGHER THAN THE MIDDLE OF
THE FENCE. CHECK WITH A LEVEL IF NECESSARY.
2. INSTALL POSTS 4 FEET APART IN CRITICAL AREAS AND 6 FEET APART ON STANDARD
APPLICA TIONS.
J. INSTALL POSTS 2 FEET DEEP ON THE DOWNSTREAM SIDE OF THE SILT FENCE, AND AS CLOSE AS
POSSIBLE TO THE FABRIC, ENABLING POSTS TO SUPPORT THE FABRIC FROM UPSTREAM WATER
PRESSURE.
4. INSTALL POSTS WITH THE NIPPLES FACING AWAY FROM THE SILT FABRIC.
5. ATTACH THE FABRIC TO EACH POST WITH THREE TIES, ALL SPACED WITHIN THE TOP 8 INCHES
OF FABRIC. ATTACH EACH TIE DIAGONALLY 45 DEGREES THROUGH THE FABRIC, WITH EACH
PUNCTURE AT LEAST 1 INCH VERTICALLY APART. ALSO, EACH TIE SHOULD BE POSITIONED TO HANG
ON A POST NIPPLE WHEN TIGHTENED TO PREVENT SAGGING.
6. WRAP APPROXIMATELY 6 INCHES OF FABRIC AROUND THE END POSTS AND SECURE WITH 3 TIES.
7. NO MORE THAN 24 INCHES OF A 36 INCH FABRIC IS ALLOWED ABOVE GROUND LEVEL.
8. THE INSTALLATION SHOULD BE CHECKED AND CORRECTED FOR ANY DEVIATIONS BEFORE
COMPACTION.
9. COMPACTION IS VITALLY IMPORTANT FOR EFFECTIVE RESULTS COMPACT THE SOIL IMMEDIATELY
NEXT TO THE SILT FENCE FABRIC WITH THE FRONT WHEEL OF THE TRACTOR, SKID STEER, OR
ROLLER EXERTING AT LEASY 60 POUNDS PER SQUARE INCH. COMPACT THE UPSTREAM SIDE FIRST,
AND THEN EACH SIDE TWICE FOR A TOTAL OF 4 TRIPS.
MAINTENANCE
INSPECT SEDIMENT FENCES AT LEAST ONCE A WEEK AND AFTER EACH RAINFALL. MAKE ANY
REQUIRED REPAIRS IMMEDIA TEL Y.
SHOULD THE FABRIC OF A SEDIMENT FENCE COLLAPSE, TEAR, DECOMPOSE, OR BECOME INEFFECTIVE,
REPLACE IT PROMPTLY.
REMOVE SEDIMENT DEPOSITS AS NECESSARY TO PROVIDE ADEQUATE STORAGE VOLUME FOR THE
NEXT RAIN AND TO REDUCE PRESSURE ON THE FENCE. TAKE CARE TO AVOID UNDERMINING THE
FENCE DURING CLEANOUT.
REMOVE ALL FENCING MATERIALS AND UNSTABLE SEDIMENT DEPOSITS AND BRING THE AREA TO
GRADE AND STABILIZE IT AFTER THE CONTRIBUTING DRAINAGE AREA HAS BEEN PROPERLY
STABILIZED.
Outlet zone
lergency
Spillway
C
CONSTRUCTION SPECIFICATIONS
1. Grade the basin so that the bottom is level front to back and side to
side.
2. Install the coir fiber baffles immediately upon excavation of the basins.
Extend 9 gauge wire to basin side or install T-post to anchor
J. Install posts across the width of the sediment trap (Practice 6.62,
baffle to side of basin and secure to vertical post
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 o
minimum of 2 inches lower than the top of the earthen embankment.
5. Install of least three rows of baffles between the inlet and outlet
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discharge point. Basins less than 20 feet in length may use 2 baffles.
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6. Attach a 9 gouge high tension wire strand to the steel posts at o
Variable Depth
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 o permanent stormwater basin of a greater depth, the baffle
height should be based on the pool depth during use as o temporary
Secure bottom of baffle to ground with
sediment basin.
12wstaplesatl2wmaximumspacing.
7. Extend 9 gauge minimum high tension wire strand to side of basin or
_.
install steel T-posts to anchor baffle to side of basin and secure to
vertical end posts as shown in Figure 6.65b.
8. Drape the coir fiber mat over the wire strand mounted at a height of 6
Baffle Material
inches above the spillway elevation. Secure the coir fiber mot to the wire
strand with plastic ties or wire fasteners. Anchor the matting to the sides
and floor of the basin with 12 inch wire staples, approximately 1 ft apart,
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along the bottom and side slopes of the basin.
9. Do not splice the fabric, but use a continuous piece across the basin
le
10. Adjustments may be required in the stapling requirements to fit
individual site conditions.
CONTINUE FILTER FABRIC
BEYOND RIP RAP APRON
W2
Wf
(3*Do)
Lo
(Apron Length)
RIP RAP APRON STABILIZATION DETAIL
(NOT TO SCALE)
Inspect baffles at least once a week and after each rainfall. Make any
required repairs immediately.
Be sure 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 ovoid damaging the baffles during cleanout, and replace if
damaged during cleanout operations. Sediment depth should never exceed
half the designed storage depth.
After the contributingdrainage area has been properly stabilized remove all
9 P P y
baffle materials and unstable sediment deposits, bring the area to grade,
and stabilize it.
CONSTRUCTION SPECIFICATIONS
PLACE RIPRAP SO THAT IT FORMS A DENSE,
WELL -GRADED MASS OF STONE WITH A MINIMUM OF
VOIDS. THE DESIRED DISTRIBUTION OF STONES
THROUGHOUT THE MASS MAY BE OBTAINED BY
SELECTIVE LOADING AT THE QUARRY, AND
CONTROLLED DUMPING DURING FINAL PLACEMENT.
PLACE RIPRAP TO ITS FULL THICKNESS IN ONE
OPERATION. DO NOT PLACE RIPRAP BY DUMPING
THROUGH CHUTES OR OTHER METHODS THAT
CAUSE SEGREGATION OF STONE SIZES. TAKE CARE
NOT TO DISLODGE THE UNDERLYING BASE OR
FILTER WHEN PLACING STONES.
MAINTENANCE
RIPRAP SHOULD BE INSPECTED PERIODICALLY AND
AFTER HEAVY RAINFALLS FOR SCOUR OR
DISLODGED STONES. CONTROL OF WEED AND
BRUSH GROWTH MAY BE NEEDED IN SOME
LOCATIONS. IMMEDIATELY MAKE ALL NEEDED
REPAIRS TO PREVENT FURTHER DAMAGE.
Compacted soil 2'
�-� min >I
-
III6 !I t
'�...'_ g' typical ---�-
Figure 6.20a Temporary earthen diversion dike.
CONSTRUCTION SPECIFICATIONS
1. REMOVE AND PROPERLY DISPOSE OF ALL TREES, BRUSH, STUMPS, AND OTHER
OBJECTIONAL MATERIAL.
2. ENSURE THAT THE MINIMUM CONSYRUCTED CROSS SECTION MEETS ALL DESIGN
REQUIREMENTS.
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 ROOM AROUND DIVERSIONS TO PERMIT MACHINE
REGRADING AND CLEANOUT.
5. VEGETATE THE RIDGE IMMEDIATELY AFTER CONSTRUCTION UNLESS IT WILL
REMAIN IN PLACE LESS THAN 30 WORKING DAYS.
MAINTENANCE
INSPECT TEMPORARY DIVERSIONS ONCE A WEEK AND AFTER EVERY RAINFALL.
IMMEDIATELY REMOVE SEDIMENT FROM THE FLOW AREA AND REPAIR THE DIVERSION
RIDGE.
CHECK OUTLETS AND MAKE TIMELY REPAIRS AS NEEDED TO AVOID GULLY FORMATION.
WHEN THE AREA ABOE THE TEMPORARY DIVISERSION IS PERMANENTLY STABILIZED,
REMOVE THE DIVERSION AND FILL AND STABILIZED THE CHANNEL TO BLEND WITH THE
NATURAL SURFACE.
TEMPORARY DIVERSION DITCH
(NOT TO SCALE)
Arm Assembly
�- 'L• Enclosure
ntry
PERSPECTIVE VIEW W�uit
PVC End PVC Vmt
PVC Elbow pig schedule 40
CapR
Water surface
7 PVC End
Cap Schedule 40
PVC TeeFj�'
e PVC Pipe
in PVC Tee orifice
de Fledble Plate
Hon
e
Bottom surface
ENb VIEW FRONT VIEW
10101►rw9�3.r.Irrr.�y�xyt�ry�rrr.�
18" min
6.20.1
• Dews wring -Allow the maximum reasonable detention period before the
basin is completely dewaternd (at least 24 hours).
• Inflow rate -Reduce the inflow velocity and divert all sediment -free
runoff.
Plan View
Inflow
structure
i
Emergency
spillway
Average __ Area* \
Width W L
^ Arm of burin water swface at
tap of principal spillway elevation
V Freeboard
Embankment
Inflow Baffles
structure
6' min. invert elevation of
urns
emergency spillway
cy
Espillwa
Fil rfabric
e
Sdiment Cross -Section
storage zone View
Figure 6.64c Example of a sediment basin with a skimmer outlet and emergency spillway. From Pennsylvania
Erosion and Sediment Pollution Control Manual, March, 2000.
6.64.6
aev.6ro6
SKIMMER SEDIMENT
BASIN
1. Clear,grub, and strip the area under the embankment of all vegetation and root mat.
Remove all surface soil containinghigh amounts of organic matter and stockpile or dispose of it
9 9 P P
properly. Haul all objectionable material to the designated disposal area. Place temporary
sediment control measures below basin as needed.
2. Ensure that fill material for the embankment is free of roots, woody vegetation, organic
matter, and other objectionable material. Place the fill in lifts not to exceed 9 inches, and
machine compact it. Over fill the embankment 6 inches to allow for settlement.
3. Shape the basin to the specified dimensions. Prevent the skimming device from settling
into the mud by excavating a shallow pit under the skimmer or providing a low support under
the skimmer of stone or timber.
4. Place the barrel (typically 4-inch Schedule 40 PVC pipe) on a firm, smooth foundation of
impervious soil. Do not use pervious material such as sand, gravel, or crushed stone as backfill
around the pipe. Place the fill material around the pipe spillway in 4-inch layers and compact it
under and around 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 compacting
under the pipe haunches.
Place a minimum depth of 2 feet of compacted backfill over the pipe spillway before
crossing it with construction equipment. In no case should the pipe conduit be installed by
cutting a trench through the dam after the embankment is complete.
5. Assemble the skimmer following the manufactures instructions, or as designed.
6 Lay tho assembled skimmr on the bottom of the basin with the flexible joint at the inle
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of the barrel pipe. Attach the flexible joint to the barrel pipe and position the skimmer over the
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excavated pit or support. Be sure to attach a rope to the skimmer and anchor it to the side of
the basin. This will be used to pull the skimmer to the side for maintenance.
7. Earthen 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 the spillway. The spillway should be lined with
laminated plastic or impermeable geotextile fabric. The fabric must be wide and long enough to
cover the bottom and sides and extend onto the top of the dam for anchoring in a trench. The
edges may be secured with 8-inch staples or pins. The fabric must be long enough to extend
down the slope and exit onto the stable ground. 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 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 that water cannot
flow under the fabric. Secure the upper edge and side of the fabric in a trench with staples or
pins. (Adapted from "A Manual for Designing, Installing and Maintaining Skimmer Sediment
Basins." February, 1999. J.W. Faircloth & Son).
8. Inlets - Discharge water into the basin in a manner to prevent erosion. Use temporary
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. (References: Runoff Control Measures and
Outlet Protection).
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9. Erosion control -Construct the structure so that the disturbed area is minimized. Divert
surface water away from the bare areas. Complete the embankment before the area i
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cleared. Stabilize the emergency spillway embankment and all other disturbed areas
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above the crest of the principal spillway immediately after construction (References:
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11. After all the sediment -producing areas have been permanently stabilized, remove the
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areas and stabilize properly. (References: Surface Stabilization).
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INSPECT SKIMMER SEDIMENT BASINS AT LEAST WEEKLY AND AFTER EACH
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(ONE-HALF INCH OR GREATER) RAINFALL EVENT AND REPAIR
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IMMEDIATELY. REMOVE SEDIMENT AND RESTORE 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 IT CAN BE EXCAVATED. EXCAVATE THE SEDIMENT FROM THE
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ENTIRE BASIN, NOT JUST AROUND THE SKIMMER OR THE FIRST CELL. MAKE SURE
VEGETATION GROWING IN THE BOTTOM OF THE BASIN DOES NOT HOLD DOWN T
SKIMMER.
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REPAIR THE BAFFLES IF THEY ARE DAMAGED. RE -ANCHOR THE BAFFLES IF WATE
IS FLOWING UNDERNEATH OR AROUND THEM.
IF THE SKIMMER ARM OR BARREL PIPE IS CLOGGED, THE ORIFICE CAN BE
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REMOVED AND THE OBSTRUCTION CLEARED WITH A PLUMBER'S SNAKE OR BY
FLUSHING WITH WATER. BE SURE AND REPLACE THE ORIFICE BEFORE
REPOSITIONING THE SKIMMER.
CHECK THE FABRIC LINED SPILLWAY FOR DAMAGE AND MAKE ANY REQUIRED
REPAIRS WITH FABRIC THAT SPANS THE FULL WIDTH OF THE SPILLWAY. CHECK
THE EMBANKMENT,SPILLWAYS, AND OUTLET FOR EROSION DAMAGE, AND INSPE
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THE EMBANKMENT FOR PIPING AND SETTLEMENT. MAKE ALL NECESSARY REPAIR
IMMEDIATELY. REMOVE ALL TRASH AND OTHER DEBRIS FROM THE SKIMMER AND
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POOL AREAS.
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FREEZING WEATHER CAN RESULT IN ICE FORMING IN THE BASIN. SOME SPECIAL
PRECAUTIONS SHOULD BE TAKEN IN THE WINTER TO PREVENT THE SKIMMER
FROM PLUGGING WITH ICE.
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EE PROJECT: 5086
S-6
OF 9