SW7070332_APPROVED PLANS_20070620

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
DOC TYPE
❑ CURRENT PERMIT
PPROVED PLANS
❑ HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATEj�
YYYYMMDD

1
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NC DOT
HIGHWAY
17 BY-PASS
HIGHWAY 55
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50 0 25 50 100
C
+
(IN FEET )
1 inch = 50 ft.
w A. UNMONUMENTED POINT
a2~w �F IRON PIN FOUND
2 o RIGHT—OF—WAY MONUMENT
REVISED 20JUNE20O7 PER NCDENR DIVISION OF WATER QUALITY
Im
US HIGHWAY 17
NORTH
US HIGHWAY 17
SOUTH
NC HIGHWAY
55
VINCINITY MAP
NTS
NO WETLANDS EXIST ON THIS SITE PER MR. SCOTT JONES,
US ARMY CORP OF ENGINEERS
SHEET 2 OF 8
GRADING AND STORM DRAINAGE
DUNN MINISTORAGE SITE
BLUEBERRY LANE
DATE, 08_MAR _07
JOB NO. __ 2005301
SCALE, I' - 50__
ROBERT M. CHILES, P.E.
ENGINEERS AND CONSULTANTS
NEW BERN, NORTH CAROLINA

EXTEND UP CHANNEL BF
6 INCHES ABOVE TOP OF
CLASS A OR B RIP RAP
IM21
60' 1510
L5 TIMES MAXIMUM STONE DIAMETER FILTER FABRIC
(6 INCHES MINIMUM)
SECTION
FWm 5.41 Rif l ou/lei protection
(TYPICAL)
WELL DEFINED CHANNEL
AT POND RISER OUTLET
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PNG\ ribs by
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18'0
90'
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1.5 TIMES MAXIMUM STONE DIAMETER FILTER FABRIC
(6 INCHES MINIMUM)
FTquro 6.41 RprW outlet Froteetbn
(TYPICAL)
NMI
INTO POND
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US HIGHWAY 17
NORTH
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VINCINITY MAP NTS
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1'
NC DOT
HIGHWAY
17 BY—PASS
HIGHWAY 55
�3�yS7Z�
Q UNMONUMENTED POINT
4F
IRON
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FOUND
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RIGHT—OF—WAY
MONUMENT
The Owners of the property located
of 160 Blueberry Road wish to
devefope a minnaroge facility on
the site.
The site is currently o field oath an
existing aveway life. Thwesl
bounded by Blueberry R
north and the US Highwa
Bypass to the south and The site will consist of me
units and a paved or gravel drive
between the builcinstS
CONSTRUCiI SEQUENCE
The limits of di rbance will be
surrounded sediment fence.
The grave onslruclion entrance will
be irn d d.
Fill will a placed around the
peril eter, slcpetl per the plans, and
st ilized with sewing.
P rid will be excavted, sloped per
he plans, and stabilized with
seeing.
Catch Basins and associated piping
will be installed, outlet stabilization for
the piping will be installed. Sedmed
control measures for drop inlets w4
11
be installed.
Seeding will be installed as the job
progresses.
Aggregate base course will be
installed in the areas to be paved
and building pods will be filled to
preconstruction grade.
Construction of the buildings will likely
commence prior to paving of the
parking areas.
After seeded areas are stabilized.
project will be cleaned up with
removal of sediment fence, sediment
removedfrom pond forebay, et
celra
r, \ i P lmnrhy
t
tit
6.06 GRAVEL CONSTRUCTION
ENTRANCE
P 6,11 PERMANENT SEEDING
T S 6.10 TEMPORARY SEEDING
DT DROP INLET PROTECTION
1 SEE DETAIL
6,15 RIP RAP
OUT
[�>
OUTLET PROTECTION
SEE DETAIL
- �--�o- 6,62 SEDIMENT FENCE
' 6,83 STONE CHECK DAM
SHEET 3 OF 8
SEDIMENT CONTROL MEASURES
DUNN MINISTORAGE SITE
BLUEBERRY LANE
2 TOWNSHIP CRAVEN CO. NORTH CAROLINA
DATE, __OB MAR_07 ROBERT M. CHILES, P.E.
JOB NO, 2005301 ENGINEERS AND CONSULTANTS
1" = 1 NEW BERN, NORTH CAROLINA

POND PLAN 1 "=30'
basin area ' 128406 2.95; _
C"Coetf. product buildings sidewalks ROADWAY PARKING
'
:BUILDINGS u 2987500 0.95p 2838125 ;.... 9600 0 0' 503651 0685836! _.
!ROADWAY 1 000, 095 000, C 6600 0; 0i 01
--
1PARKING 50365001 095 4784675; 109251 - 0' ( 1
1 15622
jSIDEWALKS 0l 095 000!-- 001 2750� ! 01
- - - _
!GRASS 48166.00, 0.55 26491.30 WEIGHTED "C" 1.1057391
impervious area =1 80240.00i 1.84 102719.30 0.801 29875r 0.691 0 0 0! 01 50365' 1.16 1 842057E
t im
pervious 1 62 49j
- t
SA/DA CALCULATION
FROM CHART 4 90%1SS SA/DA 9� ORIFICE OUTLET FLOW CALCULATIONS ;
_ - _ .�
.
GNEN: ( _.-
3o IMPERVIOUS 4 FT DEPTH ;
Q=CA(2GH)Ds
60 5
62.49 5.47 ✓ 10 year peak run-off ,WHERE '
70 6 Q=;CIA j 3.97863 C(COEFF,unVess)= 0.6I
where C=1 0.80' A(AREA, SO FT)= 0.01 j
SA= 7029.266 I= 2J; G(GRAVITY)= 32.2�1.25IN DIAMETER ORIFICE
IW= 48.405461 A=I 1.84' H(AVERAGE HEAD, FEET)= 0.381
L= 145.21638 __. i Q=1 0.031cfs 1.763032
_ _ _.
permanent pool elevation 4 00
pond data I main body foretotal drawdown time, hrs= 3.9 DAYS
_ __ _
elevation area !volume !area volume area volume! -
0.00 % 2104.21 0, 118.8 01 U231 0' I !
1.001 2621.1 2362 651 380 5 249 65� 3(l01 61 - 2612.3 RISER OUTLET FLOW CALCULATIONS(WIER) f
2.00 3189.4 2905 251 668 4 524 45 3857.8' 3429.1 GNEN:
- _ _
{ j' 4193.751 1682.9 1175 65' 68811 5369.4 Q=2/3(C3`b"(2G)o5,H�z"
_._ j_.._
3.00, ✓ 5198.1
4.00i ✓ 7837.41' 6517.75 2987.7 233531! 10825.1' 8853.051 WHERE
!total 15979.44otal 4285.05 total 20264.45 Ci(COEFF unnless)=l 0.55
5.001 - 12490. 11657.551 b (WIDTH, FT)= 6.28 __. (... _.
600'foreba volume percentage 126.816088 ! 25036.9 HAVERA G(GRAvnYP 32.2j 241NDIAMETERORIFICE
14268.7 13379.35
Y P 9 ! ( GE HEAD, FEET)'
permanent pool area _ 1 10825.1 ! Q-' j 18.5 CFS I
_
1" RUNOFF VOLUME 'pond rise% volume 34.19%
8559.941671cu It / pond rise elevation 0.771ff j
O.oSf,OaI(61.9F)
Vo�ti ✓' t %,�v)zgj�lak,Ko6�f'� _ 3
/2
6" GALV. WIRE TRASH GRATE -
RISER TOP=BENCHMARK, REMOVE SEDIMENT IF POND LEVEL IS 3.80' FROM RISER
TOP OF RISER EL.=4.80'
STORM POOL ELEVATION 4.77'
8" 0 DRAWDOWN PIPE
PERMANENT POOL ELEVATION 4.0' SPACERS
1.25"0 DRILLED ORIFICE 24"0 CMI
SECTION AT FOREBAY WEIR
SCREENING
BOTTOM 0 EL. 0.0' /-
1
US HIGHWAY 17
US HIGHWAY 17
SOUTH
NC HIGHWAY
55
VINCINITY MAP NTS
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STANDARD BRICK DROP INLET
NC DOT STD. NO. 840.15 W."
12' WIDE TOP OF BANK EL. 6.0' SEE PLAN
SUBMERGED
SHELF ,
1- 15"0 CMP OUTLET ® 0.1%
6
6'x6'xl' CONC. BASE
wA3) #4 REBAR EACH DIRECTION
RISER DETAIL
JUL 0 3 2007
SHEET 4 OF 8
STORMWATER DETAILS
DUNN MINISTORAGE SITE
BLUEBERRY LANE
POND CROSS SECTION nts
REVISED 29JUNE2007 PER NCDENR DIVISION OF WATER QUALITY
REVISED 20JUNE2007 PER NCDENR DIVISION OF WATER QUALITY
DATE, 08_MAR _07
JOB NO. __ 2005301
SCALE, AS -SHOWN
ROBERT M. CHILES, P.E.
ENGINEERS AND CONSULTANTS
NEW BERN, NORTH CAROLINA

® 6.O6 TEMPORARY GRAVEL CONSTRUCTION ENTRANCE/EXIT 6.10 TEMPORARY SEEDING
DEFINITION A graveled area or pod located at points where DEFINITION Planting rapid —growing annual grasses, small
vehicles enter and leave a construction site, grains, or legumes to provide initial, temporary
cover for erosion control on disturbed areas.
PURPOSE To provide a buffer area where vehicles can drop
their mud and sediment to avoid transporting it PURPOSE To temporarily stabilize denuded areas that will
onto public roads, to control erosion. from surface not be brought to final grade for a period of more
runoff, and to help control dust. that 30 working days.
CONDITIONS WHERE Wherever traffic will be leaving a construction Temporary seeding controls runoff and erosion
PRACTICE APPLIES site and moving directly onto a public road or until permanent vegetation or other erosion con —
other paved off —site area. Construction plans trol measures can be established. In addition, it
should limit traffic to properly constructed provides residue for soil protection and seedbed
entrances. preparation and reduces problems of mud and dust
DESIGN CRITERIA Aggregate Size — Use 2-3 inch washed stone. production from bare soil surfaces during con—
struction.
Dimensions of gravel pad — CONDITIONS WHERE On any cleared, unvegetated, or sparsely vegetated
Thickness: 6 inch minimum PRACTICE APPLIES soil surface where vegetative cover is needed for
Width: 12—ft minimum or full width at all less than 1 year. Applications of this practice
points on the vehicular entrance and exit area, whichever is greater include diversions, dams, temporary sediment
Length: 50—ft minimum basins, temporary road banks, and topsoil stock—
piles.
Location — Locate construction entrances and exists to limit sediment from leaving the site and PLANNING Annual plants, which sprout and grow rapidly and
to provide for maximum utility by all construction CONSIDERATIONS survive for only one season, are suitable for
vehicles (Figure 6.06a). Avoid steep grades and establishing initial or temporary vegetative
entrances atcurves in public roads. cover. Temporary seeding preserves the integrity
of earthen sediment control structures such as
Washing — If conditions at the site are such that dikes, diversions, and the banks of dams and
most of the mud and sediment are not removed by sediment basins. It con also reduce the amount of
vehicles traveling over the gravel, the tires maintenance associated with these devices. For
should be washed. Washing should be done on an example the frequency of sediment basin cleanouts
area stabilized with crushed stone that drains will be reduced if watershed areas, outside the
into a sediment trap or other suitable disposal active construction zone, are stabilized.
area. A wash rack may also be used to make wash—
ing more convenient and effective. Proper seedbed preparation, selection of appropri—
ate species, and use of quality seed are as impor—
CONSTRUCTION 1. Clear the entrance and exit area of all veget— tant in this practice as in Practice 6.11, PERMA—
SPECIFICATIONS ation, roots, and other objectionable material NENT SEEDING. Failure to follow established
and properly grade it. guidelines and recommendations carefully may
2. Place gravel to the specific grade and dimen— result in an inadequate or short—lived stand of
sions shown on the plans, and smooth it. vegetation that will not control erosion.
3. Provide drainage to carry water to a sediment
trap or other suitable outlet. Temporary seeding provides protection for no more
4. Use geotexile fabrics because they improve than 1 year, during which time permanent stabili—
stability of the foundation in locations notion should be initiated.
subject to seepage or high water table.
SPECIFICATIONS Complete grading before preparing seedbeds and
MAINTENANCE Maintain the gravel pad in a condition to prevent install all necessary erosion control practices,
mud or sediment from leaving the construction such as dikes, waterways and basins. Minimize
site. this may require periodic topdressing with steep slopes because they make seedbed preparation
2—inch stone. After each rainfall, inspect any difficult and increase the erosion hazard. If
structure used to trap sediment and clean it out soils become compacted during grading, loosen them
as necessary. Immediately remove all objection— to a depth of 6-13 inches wing a ripper, harrow,
able materials spilled, washed, or tracked onto or chisel plow.
public roadways.
SEEDBED PREPARATION
Good seedbed preparation is essential to success—
ful plant establishment. A good seedbed is well —
pulverized, loose, and uniform. Where hydroseed—
ing methods are used, the surface may be left with
3d Sd 3d a more irregular surface of large clods and
d d stones.
{ t}=r =
6 R°�°lncs ffc-F=PIPE jd xi'a_:--- f�IPE LIMING — Apply lime according to soil test recom—
�� - mendations. If the pH (acidity) of the soil is
i"_. d —{ d not known, an application of ground agricultural
CLASS A OR B RIP RAP CLASS A OR 8 RIP RAP limestone at the rate of 1 to 1 1/2 tons/acre on
PLAN PLAN 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
4d d 4d d higher need not be limed.
_-4=PIPE -.—t-PIPE- FERTILIZER — Base application rates on soil tests.
d 7 d When these are not possible, apply a 10-10-10
grade fertilizer at 700-1,000 lb/acre. Both
15 TWS lwxlla R sIIIE FILTER FABRIC to nhEs N4xIMN sTuc nlwcrr FILTER FABRIC fertilizer and lime should be incorporated into
a WHE: the top 4-6 inches of soil. If a hydraulic seeder
SECTION SECTION is used, do not mix seed and fertilizer more than
30 minutes before application.
Figure 6.41 Rlprep wflet mteptim Figure 6.41 Riprep outlet nvtedbn (TWICAL) SURFACE ROUGHENING — If recent tillage operations
(TYPICAL)
have resulted in a loose surface, additional
roughening may not be required except to break up
WELL DEFINED CHANNEL INTO POND OR OPEN AREA 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
that 3:1 on the contour before seeding (Practice
6.03, SURFACE ROUGHENING).
- PLANT SELECTION
Select an appropriate species or species mixture
9 ,/r N.eoxnxc see from Table 6.10a, for din in late winter and
F;
.• . nwn /
11 p0LL Np1K ! early spring, Table 6.10b for summer, and Table
i1 6.10c for fall.
12' MIN.
SuU rosT. a _... �..
� r gger � adol wr
ri u e 6D6u 6m 1 enlmnre ea➢ Ixe s retlimenl Lum 1,,,,nq IM1e ; •1 .on site Imod;Getl from Vo SWCC).
NITS
SEEDING
Evenly apply seed using a cyclone seeder (broad—
cast), drill, cultipacker seeder, or hydroseeder.
Use seeding rates given in Tables 6.10a-6.10c.
Broadcast seeding and hydroseeding are appropriate
for steep slopes where equipment cannot be driven.
Hand broadcasting is not recommended because of
the difficulty in achieving a uniform distribu—
tion.
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.
6.10 TEMPORARY SEEDING continued
MULCHING
The use of 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 fail 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 concen—
trated waterflow, as in channels, anchor mulch
with netting (Practice 6.14, MULCHING).
MAINTENANCE Reseed and mulch areas where seeding emergence is
poor, or where erosion occurs, as soon as possi—
ble. Do not mow. Protect from traffic as much as
possible.
TABLE 6.10b TEMPORARY SEEDING RECOMMENDATIONS FOR SUMMER
SEEDING MIXTURE
Species Rate (lb/acre)
German millet 40
SEEDING DATES
Apr. 15 — Aug. 15
SOIL AMENDMENTS
Follow recommendations of soil tests or apply
2,000 lb/acre ground agricultural limestone and
750 Ib/ocre 10-10-10 fertilizer.
MULCH
Apply 4,000 lb/acre straw. Anchor straw by tack—
ing 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 follow—
ing erosion or other damage.
TABLE 6.10c TEMPORARY SEEDING RECOMMENDATIONS FOR FALL
SEEDING MIXTURE
Species Rate (lb/acre)
Rye ;grain) 120
SEEDING DATES
Aug. 15 — Dec. 30
SOIL AMENDMENTS
Follow recommendations of soil tests or apply
2,000 lb/acre ground agricultural limestone and
1,000 lb/acre 10-10-10 fertilizer.
MULCH
Apply 4.000 lb/acre straw. Anchor straw by tack—
ing 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 extend temporary cover beyond
June 15, overseed with 50 lb/acre Kobe in late
February or early March.
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SHEET 5 OF 8

6.11
PERMANENT SEEDING —CONTINUED
DEFINITION Controlling runoff and erosion on disturbed areas
It is as Important to add lime as to add fertiliz—
by establishing perennial vegetative cover with
er. Lime is used primarly as a pH, or acidity,
PS seed.
modifier, but Is also supplies calcium and magne—
sium, which are important plant nutrients. By
PURPOSE To reduce erosion and decrease sediment yield from
increasing soil pH it also makes other nutrients
disturbed areas, and to permanently stabilize such
more available to plants. At the same time, it
areas in a manner that is economical, adapts to
prevents aluminum toxicity by decreasing the
site condisions and allows selection of the most
solubility of soil aluminum. Many soils In North
appropriate plant materials.
Carolina are high in aluminum, which stunts plant
growth.
CONDITIONS WHERE Fine —graded areas on which permanent, long—lived
PRACTICE APPLIES vegetative cover Is the most practical or most
After seed Is In place, it must be protected with
effective method of stabilizing the soil. Perma—
a mulch to hold moisture and modify temperature
nent seeding may also be used on rough —graded
extremes, while preventing erosion during seeding
areas that will not be brought to final grade for
establishment.
a year or more.
STEEP SLOPES
Areas to be stabilized with permanent vegetation
The operation of equipment Is restricted on slops
must be seeded or planted within 30 working days
steeper than 3:1, severly limiting the quality of
or 120 calendar days after final grade Is reached,
the seedbed that can be prepared. The soil cannot
unless temporary stabilization is applied.
be sufficiently worked, and amendments cannot be
PLANNING Vegetation controls erosion by protecting bare
thoroughly Incorporated.
CONSIDERATIONS soil surfaces from raindrop Impact and by reducing
the velocity and volume of overland flow.
The most common and economical means of stabiliz—
ing disturbed soils is by seeding grasses and
legumes. The advantages of seeding over other
means of establishing plants include the smaller
Initial cost, lower labor Input, and greater
flexibility of method. The disadvantages of
seeding include:
potential for erosion during the establishment
stage,
the need to reseed areas that fall to estab—
lish,
seasonal limitations on suitable seeding
dates, and
a need for water and appropriate temperatures
during germination and early growth.
The probability of successful plant establishment
can be maximized through good planning, knowledge
of the soil characteristics (Table 6.11a), selec—
tion of suitable plant materials for the site,
good seedbed preparation, adequate liming and
fertilization, and timely planting and mainte—
nance.
SELECTING PLANT MATERIAL
Climate, soils, and topography are the major
factors affecting the suitability of plants for a
particular site. All three of these factors wry
widely across North Carolina.
To simplify plant selection, a KEY TO PERMANENT
SEEDING MIXTURES is presented In Table 6.11b. To
find seeding specifications for a specific site,
follow this key through the differnet steps to the
appropriate seeding number. Seeding mixtures
recommended here are designed for general use and
are well proven in practical field situations.
They are designed to produce maximum stabilization
and minimize the amount of maintenance and repair
required.
LAND USE Is a primary consideration in planning
permanent seedings. For this purpose land use,
whether residential, industrial, commercial, or
recreational, can be divided into two general
catergories:
High —maintenance areas are mowed frequently,
limed and fertilized regularly, and either (1)
receive Intense use (e.g.. athletic fields) or
(2) require maintenance to an aesthetic stand—
ord (e.g., home lawns). Grosses used for
these situations are long—lived perennials
that form a tight sod and are fine —leaved and
attractive in appearance. They must be well —
adapted to the geographic area where they are
planted and able to endure the stress of
frequent mowing. Sites where high —maintenance
vegetative cover is desibable include homes,
industrial parks, schools, churches, and
recreational areas.
Low —maintenance areas are moved infrequently
or not at all, and do not recieve lime and
fertilizer on a regular basis. Plants must
persist with little maintenance over long
periods of time. Grass and legume mixtures
are favored for these sites because legumes
are a source of soil nitrogen. Mixed stands
are also more resistant to adverse conditions.
Sites suitable for low —maintenance vegetation
include steep slopes, stream or channel banks,
some commercial properties, and "utility turf
areas such as roodbanks.
SEEDBED PREPARATION
The soil on a disturbed site must be amended to
provide an optimum environment for seed germina—
tion and seedling growth. The surface soil must
be loose enough for water infiltration and root
penetration. The pH (acidity or alkalinity) of
the soil must be such that is is not toxic and
nutrients are available — preferably between 6.0
and 6.5. Sufficient nutrients — added as ferti—
lizer — must be present.
Provisions for establishment of vegetation on
steep slopes can be made during final grading. In
constuction of fill slopes, for example the last
4-6 inches might be left umcompacted. A loose,
rough seedbed Is essential. Large clods and
stones provide irregularities that hold seeds and
fertilizer. Cut slopes should be roughened.
Where steepness prohibits the use of farm machin—
ery, seeding methods are limited to broadcast or
hydroseeding, with hydroseeding giving the most
dependable results. Vegetation chosen for these
slopes must not require mowing or other intensive
maintenance. Using a hydraulic seeder, seed,
fertilizer, wood fiber mulch, and a tacking agent
can be applied in one operation.
Good mulching practices are critical to protect
against erosion on steep slopes. When using
straw, anchor with netting or asphalt. On slopes
steeper than 2:1, jute, excelsior, or synthetic
matting may be required to protect the slope.
SPECIFICATIONS SEEDBED REQUIREMENTS
Establishment of vegetation should not be attempt—
ed on sites that are unsuitable due to inappropri—
ate soil texture (Table 6.11a), poor drainage,
concentrated overland flow, or steepness of slope
until measures have been taken to correct these
problems.
To maintain a good stand of vegetation, the soil
must meet certain minimum requirements as a growth
medium. The existing soils should have these
criteria:
Enough fine —grained (silt and clay) material
to maintain adequate moisture and nutrient
supply (available water capacity of at
least .05 Inches water to 1 Inch of soil).
Sufficient pore space to permit root penetra—
tion.
Sufficient depth of soil to provide an ads—
quate root zone. The depth to rock or im—
permeable layers such as hardpans should be 12
inches or more, except on slopes steeper than
2:1 where the addition of soil is not feasi—
ble.
A favorable pH range for plant growth, usually
6.0-6.5.
Freedom from large roots, branches, stones,
large clods of earth, or trash of any kind.
Clods and stones may be left on slopes steeper
than 3:1 if they are to be hydroseeded.
If any of the above criteria are not met — i.e.,
If the existing soil is too coarse, dense, shallow
or acidic to foster vegetation — special amend—
ments are required. The soil conditioners de—
scribed below may be beneficial or, preferably,
topsoil may be applied.
SOIL CONDITIONERS
In order to Improve the structure or drainage
characteristics of a soil, the following materials
may be added. These amendments should only be
necessary where soils have limitations that make
them poor for plant growth or for fine turf estab—
lishment.
PEAT — Appropriate types are sphagnum moss peat,
hypnum moss peat, reedsedge peat, or peat humus,
all from fresh —water sources. Peat should be
shredded and conditioned in storage piles for at
least 6 months after excavation.
SAND — clean and free of toxic materials
VERMICULITE — horticultural grade and free of
toxic substances.
ROTTED MANURE — stable or cattle manure not con—
taining undue amounts of straw or other bedding
materials.
THOROUGHLY ROTTED SAWDUST — free of stones and
debris. Add 6 lb. of nitrogen to each cubic yard.
SLUDGE — Treated sewage and Industrial sludges are
available in various forms; these should be used
only in accordance with local, State, and Federal
regulations.
6,11 PERMANENT SEEDING —CONTINUED
SPECIES SELECTION
Use the KEY TO PERMANENT SEEDING MIXTURES (Table
6.11b) to select the most appropriate seeding
mixture based on the general site and maintenance
factors.
SEEDBED PREPARATION
Install necessary mechanical erosion and sedimen—
tation control practices before seeding, and
complete grading according to the approved plan.
LIME AND FERTILIZER needs should be determined by
soil tests. Soil testing is performed free of
charge by the North Carolina Department of Agri—
culture soil testing laboratory. Directions,
sample cartons, and information sheets are avail—
able through county Agricultural Extension offices
or from NCDA. Because the NCDA soil testing lab
requires 1-6 weeks for sample turn —around, sam—
pling must be planned well in advance of final
grading. Testing is also done by commercial
laboratories.
When soil tests are not available, follow rates
suggested on the individual specification sheet
for seeding mix chosen. Application rates usually
fail into the following ranges:
Ground agricultural limestone:
Light —textured, sandy soils: 1-1 1/2 tons/acre
Heavy —textured, clayey soils: 2-3 tons/acre
Fertilizer.
Grasses: 800-1200 lb/acre of 10-10-10 (or the
equivalent)
Grass —legume mixtures: 800-1200 lb/acre of 5-
10-10 (or the equivalent)
APPLY LIME AND FERTILIZER evenly and incorporate
Into the top 4-6 inches of soil by diking or other
suitable means. Operate machinery on the contour.
When using a hydroseeder, apply lime and fertiliz—
er to a rough, loose surface.
Roughen surfaces
Complete seedbed preparation by breaking up large
clods and raking into a smooth, uniform surface
(slopes less than 11). Fill in or level depres—
sions that can collect water. Broadcast seed Into
a freshly loosened seedbed that has not been
sealed by rainfall.
SEEDING
SEEDING DATES given In the seeding mixture speci—
fications are designated as "best" or "possible .
Seedings properly carried out within the "best"
dates have a high probability of success. It is
also possible to have satisfactory establishment
when seeding outside these dates. However, as you
deviate from them, the probability of failure
Increases rapidly. Seeding on the last date shown
under "possible may reduce chances of success by
30-50%. Always take this Into account in schedul—
ing land —disturbing activities.
USE CERTIFIED SEED for permanent seeding whenever
possible. Certified seed Is Inspected by the
North Carolina Crop Improvement Association. It
meets published North Carolina Standard and should
bear an official `Certified. Seed" label.
Labeling of non —certified seed is also required by
law. Labels contain important Information on seed
purity, germination, and presence of weeds. Do
not accept seed containing "prohibited" noxious
weed seed.
INOCULATE LEGUME SEED with the "Rhizobium" bacte—
ria appropriate to the species of legume.
APPLY SEED uniformly with a cyclone seeder, drop —
type spreader, drill, cultipacker seeder, or
hydroseeder on a firm, friable seedbed.
When using a drill or cultipacker seeder, plant
small grains no more than 1 inch deep, grasses and
legumes no more than 1/2 Inch. Equipment should
be calibrated in the field for the desired seeding
rate.
When using broadcast —seeding methods, subdivide
the area into workable sections and determine the
amount of seed needed for each section. Apply
one—half the seed while moving back and forth
across the area, making a uniform pattern; then
apply the second half in the some way, but moving
at right angles to the first pass.
MULCH all plantings immediately after seeding.
HYDROSEEDING
Surface roughening is particularly important when
hydroseeding, as a roughened slop will provide
some natural coverage for lime, fertilizer, and
seed. The surface should not be compacted or
smooth. Fine seedbed preparation is not necessary
for hydroseeding operations; large clods, stones,
and irregularities provide cavities in which seeds
can lodge.
Rate of wood fiber (cellulose) application should
be at least 2,000 lb/acre.
Apply legume inoculants at four times the recom—
mended rate when adding inoculant to a hydroseeder
slurry.
If machinery breakdown of 1/2 to 2 hours occurs,
add 50% more seed to the tank, based on the
proportion of the slurry. remaining. This should
compensate for damage to seed. Beyond 2 hours, a
full rate of new seed may be necessary.
6.11 PERMANENT SEEDING —CONTINUED
Lime is not normally applied with a hydraulic
seeder because it is abrasive. It can be blown
onto steep slopes In dry form.
SPRIGGING
Hybrid Bermudagrass cannot be grown fro seed and
must be planted vegetatively. Vegetative methods
of establishing common and hybrid Bermudagrass,
centipedegrass, and Bahiagrass include sodding,
plugging and sprigging. Springs are fragments of
horizontal stems which Include at least one node
(pint). They are normally sold by the bushel and
can either be broadcast or planted in furrows
using a tractor —drawn tobacco or vegetable trans—
planter.
FURROWS should be 4-6 inches deep and 2 ft apart.
Place springs about 2 ft apart in the row with one
end at or above ground level.
BROADCAST springs at the specified rate. Press
into the top 1/2-2 inches of soil with a culti—
packer or with a disk set nearly straight so that
the sprigs are not brought back to the surface.
IRRIGATION
Moisture is essential for seed germination and
seedling establishment. Supplemental Irrigation
can be very helpful in assuring adequate stands in
dry seasons or to speed development of full cover.
It Is a requirement for fine turf establishment
and should be used elsewhere when feasible.
However, irrigation is rarely critical for low —
maintenance vegetation planted at the appropriate
time of the year.
TABLE 6.11q
Water application rates must be carefully con—
trolled to prevent runoff. Inadequate or exces—
sive amounts of water can be more harmful than no
supplemental water.
MAINTENANCE Generally, a stand of vegetation cannot be deter—
mined to be fully established until soil cover has
been maintained for one full year from planting.
Inspect seeded areas for failure and make neces—
sary repairs and reseedings within the same sea—
son, if possible.
RESEEDING — If a stand has inadequate cover, re—
evaluate choice of plant materials and quantities
of lime and fertilizer. Re—establish the stand
after seedbed preparation or over —seed the stand.
Consider seeding temporary, annual species if the
NURSE PLANTS
Between Apr. 15 and Aug. 15. add 10 lb/acre German
Millet or 15 Ib/ocre Sudangross. Prior to May 1
or after Aug. 15, add 25 lb/acre rye (grain).
SEEDING DATES
BEST POSSIBLE
Early spring: Feb 15 — Mar 20 Feb 15 — Apr 20
Fall: Sept i — Sept 30 Sept 1 — Oct 31
SOIL AMENDMENTS
Apply lime and fertilizer according to soil tests,
or apply 3,000-5,000 lb/acre ground agricultural
limestone (use the lower rate on sandy soils) and
1,000 lb/acre 10-10-10 fertilizer.
MULCH
Apply 4,000 lb/acre grain straw or equivalent
cover of another suitable mulch. Anchor straw by
tacking with asphalt, netting, or roving or by
crimping with a mulch anchoring tool. A disk with
blades set nearly straight can be used as a mulch
anchoring tool.
MAINTENANCE
If growth is less than fully adequate, refertilize
in the second year, according to soil tests or
topdress with 500lb/acre 10-10-10 fertilizer.
Mow as needed when sericea is omitted from the
mixture. Reseed, fertilize and mulch damaged
areas immediately.
SEEDING No. 2CP
SEEDING MIXTURE
Species Rate (lb/acre)
Tall fescue (blend of
2 or 3 im roved varieties) 200
Rye (grain 25
SEEDING DATES
Best: Sept 15 — Oct 15
Possible: Sept 1 — Oct 31 or Feb 15 — Apr 30
SOIL AMENDMENTS
Apply lime and fertilizer according to soil tests,
or apply 3,000-5,000 lb/acre ground agricultural
limestone (use the lower rate on sandy soils) and
1,000 lb/acre 10-10-10 fertilizer.
time of year is not appropriate for permanent
ApCH ly 4,000 lb/core small straw or equivalent
seeding.
cover of another suitable mulch. Anchor straw by
If vegetation fails to grow, soil must be tested
tacking with asphalt, netting, or roving or by
to determine if acidity or nutrient imbalances is
crimping with a mulch anchoring tool. A disk with
responsible.
blades set nearly straight can be used as a mulch
anchoring tool.
FERTILIZATION — On the typical disturbed site,
full establishment usually requires refertiliza—
MAINTENANCE
tion in the second crowing season. Fine turf
Fertilize according to soil tests or apply 40
requires annual maintenance fertilization. Use
lb/acre nitrogen In Jan. or Feb., 40 lb in
soil tests if possible or follow the guidelines
Sept., and 40 lb in Nov., from a 12-4-8,
given for the specific seeding mixture.
16-4-8. or similar turf fertilizer. Avoid
fertilizer application during warm weather,
6.11b KEY TO PERMANENT SEEDING; MIXTURES BASED ON SITE CHARACTERISTK
this Increases stand losses to disease.
eseed, fertilize and mulch damaged areas
Coastal Plan
immediately. Mow to a height of 2.5-3.5
A. Well— to poorly —drained soils with good
Inches as needed.
water —holding capacities TABLE 6.11r
SEEDING No. 3CP
1. Low maintenance .......... ..1CP p
2. High Maintenance.. ... ..2CP q
B. Well —drained sandy looms to excessively
well —drained sands
1. High maintenance, fine turf ......3CP r
2. Low— to medium —care lawns .....4CP s
3. Low maintenance .......... ..5PC t
TABLE 6.11p SEEDING No. 1CP
SEEDING MIXTURE
Species Rate (lb/acre)
Tall fescue 80
Pensacola Bahiagrass 50
Sericea lespedeza 30
Kobe legpedeza 10
SEEDING NOTES
1. From Sept. 1 — Mar. 1, use unscarified seri—
cea seed.
2. On poorly drained sites omit sericfa and
increase Kobe to 30 lb/acre.
3. Where a neat appearance is desired, omit
sericea and increase Kobe to 40 lb/acre.
SEEDING MIXTURE
Species Rate (bu/1,000 112)
Tifway or Tifway II Minimum: 3
hybrid Bermudagrass Rapid cover: 10
SEEDING NOTES
1. Sprig or sod. Moisture is essential during
Initial establishment. Sod must be kept well
watered for 2-3 weeks, but can be planted
earlier or later than sprigs.
2. Common
Bermuda can be seeded or sprigged but
does not produce a high —quality turf.
It is also less cold tolerant than the
hybrids, more weed prone, and a pest in
flower beds and specimen planting.
.e a .�ast�ra
SHEET 6 OF 8
D`t r SEDIMENT CONTROL SPEC

6.15 RIP RAP
SEEDING DATES
Apr - July
SOIL AMENDMENTS
Apply lime and fertilizer according to soil tests,
or apply 3,000 lb/acre ground agricultural lime-
stone and 500 lb/acre 10-10-10 fertilizer, or 50
lb/acre nitrogen from turf -type slow -release
fertilizer. Add 25-50 lb/acre nitrogen at 2- to
3-week intervals through midsummer.
SPRIGGING
Plant sprigs in furrows with a tractor -drawn
transplanter, or broadcast by hand.
FURROWS should be 4-6 inches deep and 2
ft
apart. Place sprigs about 2 ft apart In the
row with one end at or above ground level.
BROADCAST at rates shown above, and press
sprigs
into the top 1/2-2 inches of soil with a disk
set
straight so that sprigs are not brought
back
toward the surface.
MULCH
Do not mulch.
MAINTENANCE
Topdress with 40 lb/acre nitrogen in Apr., 50 lb
In May, 50 lb In June, 30 lb in July, and 25-50 lb
in Aug.
TABLE 6.11s SEEDING No. 4CP
SEEDING MIXTURE
Species Rate
Centipedegrass 10-20 Ib/ocre (seed) or
33 bu/ocre (sprigs)
SEEDING DATES
Mar. - June
(Sprigging can be done through July where water is
available for irrigation.)
SOIL AMENDMENTS
Apply lime and fertilizer according to soil tests,
or apply 300lb/acre 10-10-10.
SPRIGGING
Plant sprigs infurrows with a tractor -drawn trans-
planter, or broadcast by hand.
FURROWS should be 4-6 inches deep and 2 It apart.
Place sprigs about 2 ft apart in the row with one
end at or above ground level.
BROADCAST at rates shown above, and press sprigs
into the top 1/2-2 inches of soil with a disk set
straight so that sprigs are not
brought back toward the surface.
MULCH
Do not mulch.
MAINTENANCE
Fertilize very sparingly -20 lb/acre nitrogen In
spring with no phosphorus. Centipedegrass cannot
tolerate high pH or excess fertilizer.
TABLE 6.11t SEEDING No. 5CP
SEEDING MIXTURE
Species
Rate (lb/acre)
Pensacola Bohiagross
50
Sericeo lespedeza
30
Common Bermudagrass
10
German millet
10
SEEDING NOTES
1. Where a neat appearance is desired, omit
sericea.
2. Use common Bermudagrass only on isolated
sites where it cannot become a pest.
Bermudograss may be replaced with 5
lb/acre centipedegross.
SEEDING DATES
April 1 - July 15
SOIL AMENDMENTS
Apply lime and fertilizer according to soil tests,
or apply 3,000 lb/acre ground agricultural lime-
stone and 500 lb/acre 10-10-10 fertilizer.
MULCH
Apply 4,000 lb/acre grain straw or equivalent
cover of another suitable mulch. Anchor straw by
tacking with asphalt, netting, or roving or by
crimping with a mulch anchoring tool. A disk with
blades set nearly straight can be used as a mulch
anchoring tool.
MAINTENANCE
Refertilize the following Apr. with 50lb/acre
nitrogen. Repeat as growth requires. May be
mowed only once a year. Where a neat appearance
is desired, omit sericea and mow as often as
needed.
Definition:
A layer of stone designed to protect and stabilize areas
RR
subject to erosion.
Purpose:
To protect the soil surface from erosive forces and/or
improve stability of soil slopes that are subject to seepage
or have poor soil structure.
Conditions Where
Riprop is used for the following applications:
Practice Applies
cut -and fill slopes subject to seepage or
weathering, particularly where conditions prohibit
establishment of vegetation,
channel side slopes and bottoms,
inlets and outlets for culverts, bridges, slope
drains, grade stabilization structures, and storm
drains,
streambank and stream grades,
shorelines subject to wave action.
Planning
Riprop is versatile, highly erosion -resistant material that
Considerations
can be used effectively in many locations and in a variety
of ways to control erosion on construction sites.
6.15 RIP RAP
Size of Rip Rap
Stones
GRADED VERSES UNIFORM RIPRAP
Riprop is classes as either graded or uniform. Graded
riprap includes a wide mixture of stone sizes. Uniform
riprap consists of stones nearly all the some size.
Graded riprap is preferred to uniform riprap in most
applications because it forms a dense, flexible cover.
Uniform riprap is more open and cannot adjust as
effectively to movement of the stones. Graded riprap is
also cheaper to install requiring less hand work for
installation than uniform riprap, which must be placed in a
uniform pattern. Uniform riprap may give a more pleasing
appearance.
Riprop sizes are designated by either the mean diameter
or the weight of the stones. The diameter specification is
often misleading since the stones are usually angular.
However, common practice is to specify stone size by the
diameter of an equivalent size of spherical stone. Table
6.15a lists some typical stones by weight, spherical
diameter, and the corresponding rectangular dimensions.
These stone sizes are based upon an assumed specific
weight of 165 lb/ft.
A method commonly used for specifying the range of stone
sizes in graded riprap is to designate a diameter for which
some percentage, by weight, will be smaller. For example
"d84" specifies a mixture of stones in which 85% of the
stone by weight would be smaller than the diameter
specified. Most designs are based on "c150", or median
size stones.
Riprop and gravel are often designated by N. C.
Department of Transportation specifications (Table 6.15b).
Weight (Ib)
Mean Spherical Length
Rectangular
Diameter (ft)
(ft)
Width/Height
(ft)
50
0.8
1.4
0.5
100
1.1
1.8
0.6
150
1.3
2.0
0.7
300
1.6
2.6
0.9
500
1.9
3.0
1.0
1000
2.2
3.7
1.3
1500
2.6
4.7
1.5
2000
2.8
5.4
1.8
4000
3.6
6.0
2.0
6000
4.0
6.9
2.3
8000
4.5
7.6
2.5
20000
6.1
10.0
3.3
When considering riprap for surface stabilization, it is
important to anticipate visual impacts, including weed
control, hazards from snakes and other animals, danger of
slides and hazards to areas below steep riprap slopes,
damage and possible slides from children moving stones,
and general safety.
proper slope selection and surface preparation are
essential for successful longterm functioning of riprap.
Adequate compaction of fill areas and proper use of filter
blankets are necessary.
Sequence of construction - Schedule disturbance of areas
that require riprap protection so the placement of riprap
can follow immediately after grading. When riprap is used
for outlet protection, place the riprap before or in
conjunction with the installation of the structure so that it is
in place before the first runoff event.
Quality of Stone- Stone for riprop may consist of field stone
or quarry stone. The stone should be hard, angular, of
such quality that it will not break down on exposure to
water or weathering, and suitable in all other respects for
the purpose intended. The specific gravity of the individual
stones should be at least 2.5.
Table 6.15b
Sizes for Riprap and Erosion
Control Stone Specified by
The N. C. Department of
Transportation Rip Rap Erosion Control
Class Class Class Class
1 2 A B
Design Criteria Gradation-Riprop should be a well -graded mixture of 50%
by weight larger than the specified design size. The
diameter of the largest stone size in such a mixture should
be 1.5 times the d50 size with smaller sizes grading down
to 1 inch.
The designer should determine the riprap size that will be
stable for design conditions. Having determined the
design stone size, the designer should select the size or
sizes that equal or exceed that minimum size based on
riprop gradations commercially available in the area.
Thickness - Construction techniques, dimensions of the
area to be protected, size and gradation of the riprop, the
frequency and duration of flow, difficulty and cost of
maintenance, and consequence of failure should be
considered when determining the thickness of riprap
linings. The minimum thickness should be 1.5 times the
maximum stone diameter, but in no case less than 6
inches.
5-200 lb. 25-250 lb. 2" to 6" 5"-15"
30% shall 60% shall
weigh o weigh a min -
minimum of inum of 100 lb
60 lbs. each each
No more than No more than 10% tolerance
10% shall 5% shall weigh top and bottom
weigh less less than 50 sizes.
than 15 lb. lb. each
each
Equally dis- Equally dis-
tributed, no distributed no
gradation gradation
specified specified
Size of Stone -The sizes of stones used for riprap protection are
determined by purpose and specific site conditions.
Slope Stabilization - Riprop stone for slope
stabilization not subject to flowing water or wave
action should be sized for stability for the
proposed grade. The gradient of the slope to be
stabilized should be less than the natural angle of
repose of the stone selected. Angle of repose of
riprop stones may be estimated from Figure 6.15a.
Riprop used for surface stabilization of slopes
does not add significant resistance to sliding or
slope failure and should not be considered a
retaining wall. The inherent stability of the soil
must be satisfactory before riprap is used for
surface stabilization. Slopes approaching 1.5:1
may require special stability analysis.
Outlet protection -Design criteria for sizing stone
and determining the dimensions of riprap pads at
channel or conduit outlets are presented in
Practice 6.41. Outlet Stabilization Structure.
Filter Blanket -A filter blanket is a layer of material placed
between the riprap and the underlying soil to prevent soil
movement into or through the riprap.
A suitable filter may consist of a well -graded gravel or
sand -gravel layer or a synthetic filter fabric manufactured
for this express purpose. The design of a gravel filter
blanket is based on the ratio of particle size in the overlying
filter material to that of the base material in accordance
with the criteria below. The designed gravel filter blanket
may consist of several layers of increasingly large particles
from sand to erosion control stone.
A grovel filter blanket should have the following
relationship for a stable design:
dl5 filter < 5
d85 base
5< d15 filter _< 40
d15 base
d50 filter < 40
d50 base
In these relationships, filter refers to the overlying material
and base refers to the underlying material. These
relationships must hold between the filter material and the
base material (soil foundation) and between the riprap and
the filter. More than one layer of filter material may be
needed. Each layer of filter material should be at least 6
inches thick.
A synthetic filter fabric may be used with or in place of grovel filters.
The following particle size relationships should exist:
INSTALLATION OF NETTING AND MATTING
Products designed to control erosion should be
installed in accordance with manufacturer's in-
structions. Any mat or blanket -type product used
as a protective mulch should provide cover of at
least 30% of the surface where it is applied.
Installation is illustrated in Figure 6.14a.
Filter fabric covering a base with granular particles
containing 50% or less (by weight) of fine particles (less
than U.S. Standard Sieve no. 200 (0.074 mm)):
a. d85 base (mm)
EOS' filter fabric (mm) 1
b. total open area of filter should not exceed 36%.
. Filter fabric covering other soils:
o. EOS is no larger than U.S. Standard Sieve no. 70
(0.21 mm)
b. total open area of filter should not exceed 10%
*EOS-Equivalent opening size compared to a U.S.
standard sieve size.
No filter fabric should have less than 4% open area or an
EOS less than U.S. Standard Sieve No. 100 (0.15 mm).
The permeability of the fabric must be greater than that of
the soil. the fabric may be made of woven or nonwoven
monofilament yarns and should meet the following
minimum requirements:
thickness 20-60 mils.
grab strength 90-120 lb.
conform to ASTM D-1682 or ASTM D-177.
Filter blankets should always be provided where seepage
is significant or where flow velocity and duration of flow or
turbulence may cause the underlying soil particles to move
through the riprap.
CONSTRUCTION Subgrade preparation -Prepare the subgrade for riprop and
SPECIFICATIONS filter to the required lines and grades shown on the plans.
Compact any fill required in the subgrode to a density
approximating that o the surrounding undisturbed material
or overfill depressions with riprap. Remove brush, trees,
slumps, and other objectionable material. Cut the
subgrode sufficiently deep that the finished grade of the
riprop will be at the elevation of the surrounding area.
Channels should be excavated sufficiently to allow
placement of the riprap in a manner such that the finished
inside dimensions and grade of the riprop meet design
specifications.
Sand and gravel filter blanket -Place the filter blanket
immediately after the ground foundation is prepared. For
gravel, spread filter stone in a uniform layer to the specified
depth. Where more than one layer of filter material is
used, spread the layers with minimal mixing.
Synthetic filter fabric -Place the cloth filter directly on the
prepared foundation. Overlap the edges by at lease 12
inches, and space anchor pins every 3 feet along the
overlap. Bury the upper and lower ends of the cloth a
minimum of 12 inches below ground. Take core not to
damage the cloth when placing riprap. If damage occurs
remove the riprop and repair the sheet by adding another
layer of filter material with a minimum overlap of 12 inches
around the damaged area. If extensive damage is
suspected, remove and replace the entire sheet.
Where large stones are used or machine placement is
difficult, a 4-inch layer of fine gravel or sand may be
needed to protect the filter cloth.
Stone Placement -Placement of riprap should follow
immediately after placement of the filter. 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 riprop 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 the stones.
The toe of the riprop slope should be keyed to a stable
foundation at its base as shown on Figure 6.251b. The toe
should be executed to a depth about 1.5 times the design
thickness of the riprop and should extend horizontally from
the slope.
The finished slope should be free of pockets of small stone
or clusters of large stones. Hand placing may be
necessary to achieve the proper distribution of stone sizes
to produce a relatively smooth, uniform surface. The
finished grade of the riprap should blend with the
surrounding area. No overfoll or protrusion of riprap
should be apparent.
Maintenance In general, once a riprop installation has been properly
designed and installed it requires very little maintenance.
riprap should be inspected periodically for scour or
dislodged stones. Control of weed and brush growth may
be needed in some locations.
�s r
SHEET 7 OF 8
a 1 f SEDIMENT CONTROL SPEC

DEFINITION
PURPOSE
CONDITIONS WHERE
PRACTICE APPLIES
PLANNING
CONSIDERATIONS
DESIGN CRITERIA
CONSTRUCTION
SPECIFICATIONS
MAINTENANCE
Small temporary stone dams constructed across a
drainageway.
To reduce erosion in a drainage channel by re—
stricting the velocity of flow in the channel.
This practice may be used as a temporary or emer—
gency measure to limit erosion by reducing flow in
small open channels. Limit drainage areas to 2
acres or less. DO NOT USE CHECK DAMS IN LIVE
STREAMS.
Check dams may be used to:
reduce flow in small temporary channels that
ore degrading, but, where permanent stabili—
zation is impractical due to their short
period of usefulness;
reduce flow in small eroding channels where
construction delays or weather conditions
prevent timely installation of nonerosive
liners.
Check dams are an expedient way to reduce gullying
in the bottom of channels that will be filled or
stabilized at a later date. It is usually better
to line the channel or divert the flow to
stabilize the channel than to install check dams.
However, under circumstances where this is not
feasible, check dams may be helpful.
Check dams installed in gross —lined channels may
kill the vegetative lining if submergence after
rains is too long and/or silting is excessive.
All stone and riprap must be removed if mowing is
planned as part of vegetative maintenance.
Consider the alternative of protecting the channel
bottom with materials such as riprap, concrete,
fiberglass mat, or other protective linings in
combination with gross before selecting check
dams.
The following criteria should be used when design—
ing a check dam:
Ensure that the drainage area above the check
dam does not exceed 2 acres.
Keep the maximum height at 2 ft at the center
of the dam.
Keep the center of the check dam at least 9
inches lower than the outer edges at natural
ground elevation.
Keep the side slopes of the dam at 2:1 or
flatter.
Ensure that the maximum spacing between dams
places the toe of the upstream dam at the
some elevation as the top of the downstream
dam (Figure 6.83a).
Stabilize overflow areas along the channel to
resist erosion caused by check dams.
Use 2 to 15—inch stone (N.C. Department of
Transportation class A or class B erosion
control stone).
Key the stone into the ditch banks and extend
it beyond the abutments a minimum of 18
inches to avoid washouts from overflow around
the dam.
1. Place stone to the lines and dimensions shown
in the plan on a filter fabric foundation.
2. Keep the center stone section at least 9
inches below natural ground level where the dam
abuts the channel banks.
3. Extend stone at least 1.5 ft beyond the ditch
banks (Figure 6.83b) to keep overflow water from
undercutting the dam as it re—enters the channel.
4. Set spacing between dams to assure that the
elevation at the top of the lower dam is the some
as the toe elevation of the upper dam.
5. Protect the channel downstream from the
lowest check dam, considering that water will flow
over and around the dam (Practice 6.41, Outlet
Stabilization Structure).
6. Make sure that the channel reach above the
most upstream dam is stable.
7. Ensure that channel appurtenances, such as
culvert entrances below check dams, are not
subject to damage or blockage from displaced
stones.
Inspect check dams and channels for damage after
each runoff event.
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,
install a protective riprap liner in that portion
of the channel (Practice 6.31, Riprop—lined and
Paved Channels).
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 dams as
needed to maintain design height and cross sec—
tion.
6.62 SEDIMENT FENCE (SILT FENCE)
DEFINITION A temporary sediment barrier consisting of filter
fabric buried at the bottom, stretched, and sup—
ported by posts.
PURPOSE To retain sediment from small disturbed areas by
reducing the velocity of sheet flows to allow
sediment deposition.
CONDITIONS WHERE
PRACTICE APPLIES Below small disturbed areas less than 1/4 acre per
100 ft of fence.
Where runoff can be stored behind the sediment
fence without damaging the fence or the submerged
area behind the fence.
Do not install sediment fences across streams,
ditches, or waterways.
PLANNING
CONSIDERATIONS A sediment fence is a permeable barrier that
should be planned as a system to retain sediment
on the construction site. The fence retains
sediment primarily by retarding flow and promoting
deposition. In operation, generally the fence
becomes clogged with fine particles, which reduce
flow rate. This causes a pond to develop more
quickly behind the fence. The designer should
anticipate ponding and provide sufficient storage
areas and overflow outlets to prevent flows from
overtopping the fence. Since sediment fences are
not designed to withstand high heads, locate them
so that only shallow pools can form. Tie the ends
of a sediment fence into the landscape to prevent
flow around the end of the fence before the pool
reaches design level. Provide stabilized outlets
to protect the fence system and release stormflows
that exceed the design storm.
Deposition occurs as the storage pool forms behind
the fence. The designer can direct flows to
specified deposition areas through appropriate
positioning of the fence or by providing on exca—
vated area behind the fence. Plan deposition
areas at accessible points to promote routine
cleanout and maintenance. Show deposition areas
in the erosion and sedimentation control plan. A
sediment fence acts as s diversion if placed
slightly off the contour. This may be used by the
designer to control shallow, uniform flows from
small disturbed areas and to deliver sediment
laden water to deposition areas.
Sediment fences serve no function along ridges or
new drainage divides where there is little move—
ment of water. Confining or diverting runoff
unnecessarily with a sediment fence may create
erosion and sedimentation problems that would not
otherwise occur.
DESIGN CRITERIA Ensure that the drainage area is no greater than
1/4 acre per 100 ft fence.
Make the fence stable for the 10—yr peak storm
runoff.
Where all runoff is to be stored behind the fence,
ensure that the maximum slope length behind a
sediment fence does not exceed the specifications
shown in Table 6.62a.
Ensure that the depth of impounded water does not
exceed 1.5 ft at any point along the fence.
If nonerosive outlets are provided, slope length
may be increased beyond that shown in Table 6.62
a, but runoff from the area should be determined
and bypass capacity and erosion potential along
the fence must be checked. The velocity of the
flow at the outlet or along the fence should be in
keeping with Table 8.05d, Appendix 8.05.
TABLE 6.62o
CONSTRUCTION
SPECIFICATIONS MATERIALS
1. Use a synthetic filter fabric or a pervious
sheet of polypropylene, nylon, polyester, or
polyethylene yarn, which is certified by the
manufacturer or supplier as conforming to the
requirements shown in Table 6.62b.
Synthetic filter fabric should contain ultraviolet
ray inhibitors and stabilizers to provide minimum
of 6 months of expected usable construction life
at a temperature range of 0 to 120 degrees F.
2. Ensure that posts for sediment fences are
either 4—inch diameter pine, 2—inch diameter ook.
or 1.33 lb/linear ft steel with a minimum length
of 4 ft. Make sure that steel posts have projec—
tions to facilitate fastening the fabric.
3. For reinforcement of standard strength filter
fabric, use wire fence with a minimum 14 gauge and
a maximum mesh spacing of 6 inches.
TABLE 6.62b
SPECIFICATIONS FOR PHYSICAL PROPERTY REQUIREMENTS
SEDIMENT FENCE FABRIC Filtering Efficiency 85% (min)
Tensile Strength at Standard Strength-
20% (max.) Elongation 30 Ib/lin in (min)
Slurry Flow Rate 0.3 gal/sq ft/min (min)
CONSTRUCTION
1. Construct the sediment barrier of standard
strength or extra strength synthetic filter fab—
rics.
2. Ensure that the height of the sediment fence
does not exceed 18 inches above the ground sur—
face. (Higher fences may impound volumes of water
sufficient to cause failure of the structure.)
3. 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 overlap to the next post.
4. Support standard strength filter fabric by
wire mesh fastened securely to the upslope side of
the posts using heavy duty wire staples at least 1
inch long, or tie wires. Extend the wire mesh
support to the bottom of the trench.
5. When a wire mesh support fence is used, space
posts a maximum of 8 ft apart. Support pests
should be driven securely into the ground to a
minimum of 18 inches.
6. Extra strength filter fabric with 6—ft post
spacing does not require wire mesh support fence.
Staple or wire the filter fabric directly to
posts.
7. Excavate a trench approximately 4 inches wide
and 8 inches deep along the proposed line of posts
and upslope from the barrier (Figure 6.62a).
8. Backfill the trench with compacted soil or
gravel placed over the filter fabric.
9. Do not attach the filter fabric to existing
trees.
MAINTENANCE
MAXIMUM SLOPE LENGTH SLOPE SLOPE
AND SLOPE FOR WHICH LENGTH (ft)
SEDIMENT FENCE IS <2% 100
APPLICABLE 2 to 5% 75
5 to 10% 50
10 to 20% 25
>20% 15
Provide a riprap splash pad or other outlet pro—
tection device for any point where flow may over—
top the sediment fence, such as natural depres—
sions or swales. Ensure that the maximum height
of the fence at a protected, reinforced outlet
does not exceed 1 ft and that support post spacing
does not exceed 4 ft.
The design life of a synthetic sediment fence
should be 6 months. Burlap is only acceptable for
periods up to 60 days.
Inspect sediment fences at least once a week and
after each rainfall. Make any required repairs
immediately.
Should the fabric of a sediment fence collapse,
tear, decompose or become ineffective, replace it
promptly. Replace burlap every 60 days.
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.
TEMPORARY OR PERMANENT
SEED ALL EXPOSED SURFACES
Typical Section : Grass Lined Swale
L=The distance such that points
A and B are of equal elevation
0
f_bank u
Figure 6.83a Space check dams In a channel so that the crest
ofdownstreamdam Is atelevation of the toe of upstream dam.
Washed Stone, tYmb
ow
\ 12' J
12' Class A or B
Section A —A erosion control stone
Figure 6.83b Stone check dam
NITS
Compacted fill
Backfill min 8"
thick layer of gravel
1 14'-
511
V—trench
Extension of fabric and wire
ins^ tk- +.e.'k
Filter fabric
Figure 6.62a Installation detail of a sediment
fence.
SHEET 8 OF 8

TYPICAL
SECTION
PLANTING
1 "= 5'
SECTION
IV
PI ANTINC
SHRUBS
SYM80L
N0.
BOTANICAL NAME
COMMON NAME
SIZE
SPACING
REMARKS
S-1
88
CAREX STRICTA
UPRIGHT SEDGE
SEEDLING
12" O.C. MIN
AKA TUSSOCK SEDGE
S-2
11
CAREX CRINITA
LONG HAIR SEDGE
SEEDLING
10% OF TOTAL
PLANT ABOVE NWL
S-3
11
CAREX LURIDA
SALLOW SEDGE
SEEDLING
10% OF TOTAL
PLANT ABOVE NWL
PG-1
N/A
UNIOLA LATIFOLIA
UPLAND SEA OATS
8#/acre
.06 ocres
—0.5 Ibs
PLANT ABOVE STORM
POOL ON POND SLOP