20221128_Pages_ESC_manual

July 2001
A cooperative effort between Erosion a n d
the North Carolina Department
of Environment and Natural
Resources, and the North Sediment
Carolina Agricultural
Extension Service,supported
by the North Carolina Control
Sedimentation Control
Commission.
State of North Carolina
Michael F.Easley, Governor
North Carolina Field Manual
Department of Environment
and Natural Resources
William G.Ross,Jr.,
Secretary
Division of Land Resources
Land Quality Section

6.10 TS
Purpose To stabilize disturbed areas before final grading or in a season not suitable
for permanent seeding(Figure 6.1 Oa).
Figure 6.10a
Temporary
seeding of
Sudangrass
controls erosion
until permanent
ground cover can
be applied.
Minimum ■ Seedbed preparation: lime and fertilizer incorporated 4-6 inches,
Requirements where conditions allow, steep slopes roughened by tracking.
■ Plant selection:temporary species appropriate for season and region
(Figure 6.1Ob).
■ Seed quality:North Carolina certified seed,tested within the past 9
months.
■ Mulch: effective mulch such as clean grain straw,tacked and/or tied
down with netting to protect seedbed and encourage plant growth
(reference Practice 6.14,Mulching).
6.10.1

Temporary Seeding 13
Installation
Seedbed Apply soil amendments evenly and incorporate to a depth of 4-6 inches,
Preparation if possible. Follow recommendations of soil tests or apply 2000 lb/acre
ground agriculture limestone and 700-1000 lb/acre 10-10-10 fertilizer.
Loosen surface just before broadcasting seed (reference Practice 6.11,
Permanent Seeding).
Plant Select an appropriate temporary species based on the calendar in Figure
Selection 6.1Ob. Avoid seeding in December or January. If necessary to seed at
these times,use rye grain and a securely tacked mulch.
J I F M A M J I J A I S O N D
Mountains
Above 2500'
Below 2500' 3 5
Piedmont
Coastal Plain 4 2
Recommended Plantings
Legend
1 Korean Lespedeza with .............................. 50 lb/acre
Rye Grain.................................................. 120 lb/acre
2 Kobe Lespedeza with .................................. 50 lb/acre
Rye Grain.................................................. 120 lb/acre
3 German Millet or.......................................... 40 lb/acre
Sudangrass ................................................ 50 lb/acre
4 German Millet.............................................. 40 lb/acre
5 Rye Grain.................................................. 120 lb/acre
Figure 6.10b Calendar for scheduling temporary seedings.
6.10.2

6.10
Apply seed evenly using a cyclone seeder,rotary-spreader,drop-spreader,
cultipack seeder,or hydroseeder. Hand broadcasting is not recommended
because it is difficult to achieve a uniform stand.
Cover broadcast seed by raking or by dragging a chain. Firm lightly with
a roller or cultipicker.
When drill-seeding, plant small grains no more than 1 inch deep, and
grasses and legumes no more than 1/2 inch deep.
Mulch all seedings to reduce erosion and encourage seedling growth.
Straw mulch is commonly used on gently sloping areas. Spread evenly
at a rate of 2 tons/acre and anchor securely with tackifier,asphalt,or net-
ting. Netting is the most effective method on steep slopes and in channels
(reference Practice 6.14,Mulching).
Common ■ Lime and fertilizer not incorporated to at least 4 inches—may be lost
Trouble to runoff or remain concentrated near the surface where they may
Points inhibit germination.
■ Mulch rate inadequate or straw mulch not tacked down—results in
poor germination or failure, and erosion damage. Repair damaged
areas,reseed and mulch.
■ Annual ryegrass used for temporary seeding—ryegrass reseeds itself
and makes it difficult to establish a good cover of permanent vegeta-
tion.
■ Seed not broadcast evenly or rate too low—results in patchy growth
and erosion.
Maintenance Inspect within 6 weeks of planting to see if stands are adequate. Check
for damage after heavy rains. Stands should be uniform and dense. Fer-
tilize,reseed,and mulch damaged and sparse areas immediately. Tack or
tie down mulch as necessary.
Topdress fall plantings with 50 lb/acre nitrogen in February or March.
6.10.3

Temporary Seeding 0
6.10.4

6.11 PS
Purpose To stabilize disturbed areas with vegetation for periods longer than 12
months(Figure 6.11 a).
Figure 6.11a
Permanent cover
protects slopes
after grading.
Minimum ■ Surface roughening:slopes steeper than 3:1 should be roughened by
Requirements tracking,grooving,or furrowing.
■ Amendments:line and fertilizer,incorporated 4-6 inches where con-
ditions allow(refer to Seedbed Preparation,below).
■ Seed quality:North Carolina certified seed,tested within the past 9
months.
■ Planting date: appropriate for region and species(Figure 6.11b).
■ Plants:recommended erosion control plants are listed in Table 6.11 a.
Select a seeding mixture from those shown in Tables 6.1lb-g.
■ Mulch: 75% of the ground surface covered with approved material
(reference Practice 6.14,Mulching).
■ General: inspect seeded areas 2-4 weeks after seeding. Repair and
reseed as necessary.
6.11.1

Permanent Seeding 0
Definitions Certified seed: seed that has been inspected and tested according to offi-
cial North Carolina standards and is labeled with information on germina-
tion,purity,and contaminating species.
High maintenance: (as used in Tables 6.11b-g) plantings that receive
frequent mowing,fertilizer,and pest control.
Hulled seed: seed that has its outer protective covering,or hull,removed
to speed germination. It is also called"clean" seed. Hulled seed is not
always scarified(see below).
Inoculant (for legume seed): nitrogen-fixing bacteria, sold in airtight
plastic bags. The bacteria colonize roots of the legume,providing nitro-
gen to the plant and soil.
Legume: members of the pea family such as lespedeza or crown vetch.
Legumes are particularly suited for erosion control because they add ni-
trogen to the soil by means of bacteria that live on their roots(see inocu-
lant,above.)
Nurse crop or nurse plant: an annual species such as rye grain, Sudan-
grass,or German millet that germinates rapidly. Nurse plants are included
in mixtures to prevent erosion while slower-growing permanent plants are
developing.
Scarified seed:seed that has been treated by scratching the hard seed coat
after any hull has been removed. Scarified legume seeds germinate rap-
idly. Most unscarified seeds lie dormant until the following spring.
Sprigs: fragments of spreading grasses that include at least one node
(joint). Planting sprigs is an alternative to seeding;it is the only means of
establishing hybrid Bermudagrass,which cannot be seeded.
Installation During final grading,take soil samples from the top 6 inches in each area
to be seeded. Sample containers and directions are available from the
North Carolina Department of Agriculture (NCDA) soil testing lab, or
through county Agricultural Extension offices.
Submit samples to the NCDA or a commercial laboratory for liming and
fertilizer recommendations.*
*Agronomic Division,NC Department of Agriculture,Blue Ridge Rd.Center,Raleigh,N.C.
6.11.2

6.11
Seedbed ■ Apply ground agricultural limestone,unless a soil test indicates pH
Preparation 6.0 or greater. If a soil test is not available, use a rate based on soil
texture:
Coarse textured: 1 - 1 1/2 tons/acre
Fine textured:2-3 tons/acre
■ Apply a complete fertilizer at rates recommended by soil tests. In the
absence of soil test,use the following as a guide:
Grasses: 800-1200 lb/acre of a 10-10-10 analysis fertilizer
(or equivalent)
Grass-legume mixtures: 800-1200 lb/acre of a 5-10-10
fertilizer(or equivalent)
■ Incorporate lime and fertilizer to a depth of 4-6 inches by disking or
chiseling on slopes up to 3:1. Do not mix lime and fertilizer prior to
application.
■ Fill in depressions that can collect water. Where mowing is planned,
continue tillage until a uniform,finely pulverized seedbed is achieved.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
vi Tall fescue(above 2500')
c
Tall fescue(below 2500')
Tall fescue(low maint.)
c
0
E Tall fescue(high maint.)
d
a Common Bermudagrass
Tall fescue mixture
c
a Hybrid Bermudagrass
R
to
Common Bermudagrass
0
U
Centipedegrass I lie
- Optimum Possible
Figure 6.11 b Calendar for permanent seeding recommendations by region.
6.11.3

Permanent Seeding 13
Seeding Seeding dates:Use the seeding calendar shown in Figure 6.11b. As you
vary from the recommended dates, these probability of failure increases
rapidly. If scheduled outside these dates, use temporary seeding until
preferred date for permanent seeding(reference Practice 6.10,Temporary
Seeding).
Select a seeding mixture from Tables 6.11b-g based on region (Moun-
tains, Piedmont, Coastal Plain), soil characteristics, slope, and level of
maintenance. Table 6.11a lists characteristics and applications of grasses
and legumes used in the mixtures.
Inoculate legume seed to ensure good growth. Cut-and-fill soils are like-
ly to be deficient in the appropriate bacteria.
Seeding rates in Tables 6.1lb-g are based on poor growing conditions
that typically exist, and a need for dense growth. Higher seeding rates
will not substitute for good seedbed preparation.
Apply seed uniformly,using a cyclone seeder,drop-type spreader,drill,
cultipacker seeder, or hydroseeder. When using a drill seeder, plant rye
or other grains not more than 1 inch deep,grasses and legumes not more
than 1/2 inch. Calibrate equipment in the field.
Cover seed by raking chain-dragging, or dragging a brush or mat, then
firm the soil lightly with a roller. Seed can also be covered with hydro-
mulched wood fiber and tack. Do not roll hydro-mulched seed.
Sprigging Sprigs are sold by the bushel,and can be broadcast or planted in furrows
using a vegetable transplanter.
Make furrows 4-6 inches deep and 211 apart. Place sprigs about 2 ft apart
with one end at or above surface.
If broadcast, select rate from Table 6.11g. Press into top 1/2-2 inches of
soil with a cultipacker or mulch crimper.
Mulching Cover area evenly with approved mulch(75%cover minimum). Crimp,
tack, or tie mulch with netting. Mulching is extremely important for
successful seeding(reference Practice 6.14,Mulching).
6.11.4

6.11
Common ■ Inadequate seedbed preparation—a well tilled, limed, and fertilized
Trouble seedbed is the most important step in vegetative establishment.
Points ■ Unsuitable choice of plant materials—do not plant Bermudagrass in the
fall, Kentucky bluegrass in the Coastal Plain, or annual ryegrass in a
permanent seeding mixture.
■ Nurse crop rate too high in mixture—competes with perennial; limit
rates to those shown in Tables 6.11b-g.
■ Seeding at the wrong time of year—consult Figure 6.11b. If timing is
not right,use temporary seeding to stabilize soil until preferred seeding
dates.
■ Inadequate mulching—cover area evenly and tack or tie down well,es-
pecially on slopes,ridges,and in channels.
Maintenance Expect emergence of grasses within 4-28 days and legumes 5-28 days after
seeding,with legumes following grasses. A successful stand should exhibit
the following:
■ vigorous dark green or bluish green seedlings—not yellow
■ uniform density, with nurse plants, legumes, and grasses well inter-
mixed
■ green leaves. Perennials should remain green throughout the summer,
at least at the plant bases.
For at least a year,inspect stands for erosion or die-out. Repair damaged,
bare, or sparse areas by filling any gullies, refertilizing, reseeding, and
mulching.
Reseeding If plant cover is sparse or patchy,re-evaluate the choice of plant materials
and quantities of lime and fertilizer. Depending on the condition of the
stand,repair by overseeding or reseeding after complete seedbed prepara-
tion. If timing is bad,overseed with rye grain or German millet to thicken
the stand until a suitable time for seeding perennials.
If vegetation fails to grow,have the soil tested to determine whether acidity
or nutrient deficiency is a problem.
6.11.5

Permanent Seeding 13
Fertilization Satisfactory establishment may require refertilizing the stand in the sec-
ond growing season.
■ Do not fertilize cool season grasses in late May through July.
■ Grass that looks yellow may be nitrogen deficient.
■ Do not use nitrogen fertilizer if stand contains more than 20% le-
gumes.
Table 6.11 a
Tolerance, Maintenance, and Propagation Characteristics of Erosion Control Plants
Mainte-
Region Drainage Planting Tolerance nance
c
C C
lC N f6 c a. 4� iq O
� a8 o3 � b3ca U) om n0LLF- _-9
Grasses
Bahiagrass • • • • • • • • • • 14-28 000 •
Bermudagrass(common) • • • • • • • • • • 21 • •• •
Bermudagrass(hybrid) • • • • • • • • • — • • •
Centipedegrass • • • • • • • • • 28 • • •
Fescue,tall • • • • • • • • 5-14 • •• • •
Fescue,red • • • • •• • • • 7-28 • •• • •
German millet2 • • • • • • • • • • 4-14 •
Kentucky bluegrass • • • • • • • • • 10-28 • • •
Redtop • • • • • • • • • 5-10 •• •
Rye grain • • • • • • • • • • 4-7 •
Sudangrass • • • • • • • • • • 4-10 •
Legumes
Crown vetch • • • • • • • • 14-21 • •
Kobe lespedeza • • • • • • • • • • 5-14 • •
Korean lespedeza • • • • • • • • 5-14 •
Sericea lespedeza • • • • • • • • • • 7-28 • •
Number of days required for majority of seeds to germinate under favorable conditions.
2A/so"Foxtail millet."
6.11.6

6.11
Table 6.11b Low-maintenance Mixtures— Mountains
Seeding No.' Site Plants lb/acre
1 M Steep slopes, average Tall fescue 100
soils Sericea lespedeza2 20
Korean lespedeza 10
Redtop 5
Kentucky bluegrass 5
Nurse plants3
2M Gentle or steep slopes Tall fescue 40
with stony, dry soils Crown vetch 10
Korean lespedeza 10
Redtop 5
Nurse plant'
(If occasional mowing is desired, substitute 20 lb/acre sericea
lespedeza for crown vetch)
3M Gentle slopes, average Tall fescue 60
soils Kentucky bluegrass 10
Sericea lespedeza2 15
Korean lespedeza 10
Nurse plant3
7M Gentle or steep slopes Black locust(tree) 3
with stony, dry soils(trees) Korean lespedeza 10
Winter rye (grain) 15
Weeping lovegrass 2
Redtop 1
8M Channels Tall fescue 175-200
Kentucky bluegrass 20
Nurse plants3
Seeding numbers refer to seeding specifications in the N.C.Erosion and Sediment Control Planning and
Design Manual(1988);"M"indicates Mountain region.
2 After Aug. 15 use unscarified seed for sericea lespedeza.
3 Between May 1 and Aug. 15,add 10 lb/acre German millet or 15 lb/acre Sudangrass. Prior to May 1 or after
Aug. 15,add 40 lb/acre rye grain.
6.11.7

Permanent Seeding 13
Table 6.11c High-maintenance Mixtures— Mountains
Seeding No.' Site Plants lb/acre
4M Soils with average or Kentucky bluegrass
better moisture retention (three improved varieties) 75-100
(Shady locations: substitute 40% by weight fine fescue—hard, red or
chewings.)
5M &6M Full sun or semi-shade Tall fescue blend
including drought-prone (two or three turf types)
soils—minimum-care Kentucky bluegrass 200
lawns.
(50:50 mix of two
improved varieties) 30-50
'Seeding numbers refer to seeding specifications in the N.C.Erosion and Sediment Control Planning and
Design Manual(1988);"M"indicates Mountain region.
Table 6.11d Low-maintenance Mixtures—Piedmont
Seeding No.' Site Plants lb/acre
1 P Steep slopes or poor Tall fescue 100
soils Sericea lespedeza2 30
Kobelespedeza 10
Nurse plant'
(Eastern Piedmont: add 25 lb/acre Pensacola Bahiagrass or 10 lb/acre
common Bermudagrass.)
2P Gentle slopes, Tall fescue 80
average soil Sericea lespedeza2 20
Kobelespedeza 10
Nurse plant'
(Fall plantings: Kobe is best overseeded in late winter.)
5P Channels Tall fescue 200
Nurse plant'
Seeding numbers refer to seeding specifications in the N.C.Erosion and Sediment Control Planning and
Design Manual(1988);"P"indicates Piedmont.
2 After Aug. 15 use unscarified seed for sericea lespedeza.
3 Between May 1 and Aug. 15,add 10 lb/acre German millet or 15 lb/acre Sudangrass. Prior to May 1 or after
Aug. 15,add 40 lb/acre rye grain.
6.11.8

6.11
Table 6.11e High-maintenance Mixtures— Piedmont
Seeding No.' Site Plants lb/acre
3P Soils with average or Tall fescue
better moisture (two turf types) 200
retention—cool sites Kentucky bluegrass
(two or more improved varieties) 20
4P Dry soils, soils with Tall fescue blend
physical limitations, (three or more
or warm sites varieties—turf
types or KY-31) 200-250
Seeding numbers refer to seeding specifications in the N.C.Erosion and Sediment Control Planning and
Design Manual(1988);"P"indicates Piedmont region.
Table 6.11f Low-maintenance Mixtures—Coastal Plain
Seeding No.' Site Plants lb/acre
1 CP Well-to poorly-drained Tall fescue 80
soils with good moisture Pensacola Bahiagrass 50
retention Sericea lespedeza2 30
Kobelespedeza 10
Nurse plant'
(Poorly drained sites: omit sericea and increase Kobe to 30 lb/acre.)
5CP Dry to well-drained areas. Pensacola Bahiagrass 50
Sericea lespedeza2 30
Common Bermudagrass 10
German millet 10
(Bermudagrass may be replaced with 5 lb/acre centipedegrass.)
7CP Channels Common Bermudagraass 40-80
'Seeding numbers refer to seeding specifications in the N.C.Erosion and Sediment Control Planning and
Design Manual(1988);"CP"indicates Coastal Plain.
2 From Sept. 1 to March 1,use unscarified seed for sericea lespedeza. Where a neat appearance is required
omit sericea and increase Kobe to 40 lb/acre.
3 Between April 15 and Aug. 15,add 10 lb/acre German millet or 15 lb/acre Sudangrass. Prior to April 15 or
after Aug. 15,add 40 lb/acre rye grain.
6.11.9

Permanent Seeding 13
Table 6.11g High-maintenance Mixtures—Coastal Plain
Seeding No.' Site Plants lb/acre
2CP Well-to poorly-drained Tall fescue blend
soils with good moisture (two or three
retention improved varieties) 200 lb
Rye grain 25 lb
3CP Well-drained sandy loam Hybrid Bermudagrass
to sand (Tifway or Tifway ll) 130-140 bu
4CP Well-drained, sandy loam Centipedegass 33 bu
to sand—minimum care (sprigs)
lawns 10-20 lb
(seed)
Seeding numbers refer to seeding specifications in the N.C.Erosion and Sediment Control Planning and
Design Manual(1988);"CP"indicates Coastal Plain.
6.11.10

6.14 O
Purpose To provide temporary erosion protection and promote growth of vegeta-
tion. This is one of the most important,effective,and economical erosion-
control practices(Figure 6.14a).
Figure 6.14a
Erosion-control
matting protects
channels until
grass becomes
established.
Minimum ■ Material: as specified in the approved plan, or an equivalent mulch
Requirements selected from Table 6.14a. On steep slopes and in channels, install
and anchor matting,geofabric,or netting-over straw.
■ Coverage: at least 75%of the soil surface.
■ Anchoring method: straw or hay mulch should be anchored by
applying tackifier, stapling netting over the top, or crimping with a
mulch crimping tool. Materials that are heavy enough to stay in place
do not need anchoring(for example,bark or wood chips).
6.14.1

Mulching 13
Material Rate Requirements Notes
Per Acre
Table 6.14a ORGANIC MULCHES
Typical Mulching Straw 1-2 tons Dry, unchopped, Spread by hand or
Materials and unweathered; avoid machine; must be
weeds. tacked or tied down.
Application Rates
Wood fiber 1/2-1 ton Use with hydroseed-
or wood er; may be
cellulose used to tack straw.
Do not use in hot, dry
weather.
Wood chips 5-6 tons Air dry. Add fertilizer Apply with blower,
N. 12 lb/ton. chip handler, or by
hand. Not for fine turf
areas.
Bark 35 yd3 Air dry, shredded or Apply with mulch
hammermilled, blower, chip handler,
or chips. or by hand. Do not
use asphalt tack.
NETS AND MATS
Jute net Cover Heavy, uniform; Withstands water
area woven of single flow.
jute yarn. Used with
organic mulch.
Excelsior Cover
(wood fiber) area
mat
Fiberglass 1/2-1 ton Continuous fibers of Apply with com-
roving drawn glass bound pressed air ejector.
together with a non- Tack with emulsified
toxic agent. asphalt at rate of
25-35 gal/1000ft2.
CHEMICAL STABILIZERS(Soil binders)*
Aquatain Follow Not beneficial to
Aerospray manu- plant growth. Do not
Curasol AK facturer's attempt to seed/
Petroset SB specifica- mulch over the soil
Krete tions binder.
Crust 500
'Use of trade names does not imply endorsement of product.
6.14.2

6.14
Installation Spread mulch uniformly,by hand, with a mulch blower, or with a hy-
dromulcher. After spreading, no more than 25% of the ground surface
should be visible.
Straw mulch: apply 1-2 tons/acre (use the higher rate on steeper
slopes).
Anchor organic mulch (other than wood or bark chips) by one of the
following means,to resist runoff and wind:
■ Crimping with a mulch anchoring tool or with a weighted farm disk set
nearly straight.
■ Applying a liquid tackifier—apply emulsified asphalt 0.1 gal/yd2,
heavier at edges of area and at crests of ridges and banks. Apply other
tackifiers according to manufacturers's specifications.
■ Stapling netting securely over straw mulch (Figure 6.14b). Netting
may be the only effective anchoring method for steep slopes and chan-
nels.
Installing Bury upslope end of net in a trench 6 inches deep and unroll downgrade
Netting and (Figure 6.14b). Allow netting to lay loosely on the surface—do not
Matting stretch.
Staple strips every 1 ft across the top,and every 3 ft around the edges,bot-
tom, and down the middle. In channels, staple every 2 ft down the edges
and middle.
Overlap adjacent strips 3 inches and staple,every 3 ft,on the overlap.
To join ends of strips:overlap 18 inches and staple every 1 ft on the overlap.
An anchor slot is recommended to secure mats in channels with unstable
soils. Backfill must be well compacted.
On slopes steeper than 3:1, make a 6-inch check slot every 15 ft, insert a
fold of net into slot,backfill with soil and compact firmly.
Installing Roving is applied with a compressed air ejector,alone or over straw.
Fiber Glass ■ Apply uniformly at a rate of 0.25-0.351b/yd2.
Roving
■ Anchor with emulsified asphalt at a rate of 0.25-0.35 gal/yd.
■ On steep slopes and in channels,bury upslope end of roving and an-
chor with stakes on 10-ft centers.
6.14.3

Mulching
Compacted
backfill
Figure 6.14b
Installation of nets
and mats. 6"
� 3
Anchor
slot
a/
18"
overlap
Common ■ Inadequate coverage—results in erosion, washout, and poor plant es-
Trouble tablishment.
Points ■ Appropriate tacking agent not applied, or applied in insufficient
amount—mulch is lost to wind and runoff.
■ Channel grade and liner not appropriate for amount of runoff—results
in erosion of channel bottom. Plan modification may be required.
■ Hydromulch applied in winter—results in deterioration of mulch be-
fore plants can become established.
Maintenance Inspect after rainstorms to check for movement of mulch or erosion. If
washout,breakage,or erosion occurs,repair surface,reseed,remulch,and
install new netting. Continue inspections until vegetation is firmly estab-
lished.
6.14.4

6.23 —P W B -�
Purpose To prevent erosion on long, sloping right-of-way routes by diverting run-
off at selected intervals(Figure 6.23a).
Figure 6.23a
Right-of-way
diversions (water
bars) prevent
erosion in utility
access routes.
Minimum ■ Height: 18 inches minimum from channel bottom to top of settled
Requirements ridge.
■ Side slope: 2:1 or flatter(3:1 or flatter where vehicles cross).
■ Spacing:for right-of-way widths less than 100 ft,spacing is given in
Table 6.23a.
■ Base width of ridge: 6 ft minimum(Figure 6.23c).
Table 6.23a Slope (%) Diversion Spacing (ft)
Spacing of <5 125
Water Bars 5 to 10 100
10 to 20 75
20 to 35 50
>35 25
6.23.1

Right-of-Way Diversions
■ Grade: constant or slightly increasing,not to exceed 2%.
■ Outlet: diversion must cross the full access width and extend to a
stable outlet.
Installation Construct the diversion system as soon as the access right-of-way has
been cleared and graded(Figure 6.23b).
Locate first diversion at required distance from the slope crest depending
on steepness of right-of-way slope (Table 6.23a). Set crossing angle to
keep positive grade less than 2% (approximately 60-degree angle pre-
ferred).
Mark location and width of ridge and disk the entire length.
Figure 6.23b ,,,.,
A system of
water bars
reduces runoff
�N
accumulation
on long, sloping it
rights-of-way.
llr�ir l:(al4tilk 'Ilyl,� . .
� '10
1... 1��. ,,.I Y.HyI"INLII♦111II, (-
VIIi III It••ylll..11 14. I I�
t 'I IIIUIIIIu..41IH Y. ll�'lln, f
1.. illIUI/I.IIIII II.IY IIII Ilu•41., 1"•.
' lllu.Au •41,, �h1yJblgq•
,liil1luoly,,,IFI'Yl.�l I,,InV '� Y1''„rNu L'`/I 1/41
1111..i�Y...II' IIII, .I II1111�IV'I.. 1111t1
III, IIIU14 1 Lllt •ll(hu1. '�IY1U U..• (�,
1luw1n111w1�1111'a"'lwal.,. ," I`ry. �,/ ``,,II.
�.•'�1'II.11 W Il {41HII. II IIQI111.II/Ily .II•..t' µlull ll'Il tllll���(!\V1n1I••
1 .4Ullllll4n•••.. .1'hnl, ht............ 11lv�1
ti qpp.�•"� a �..Il I'YI ` IIII., 1•........ \1/l 11�1• y.
O��W^`Ci,r 'IIII.• `1
t"iv 1.
r o O
oo.0 �t(II k
1 �► Ihlnlll)il
6.23.2

6.23
Fill and compact ridge above design height and compact with wheeled
equipment to the design cross section(Figure 6.23c).
Construct diversions on constant or slightly increasing grade not to ex-
ceed 2%. Avoid reverse grades.
Set direction of water bars to utilize the most stable outlet locations.
If necessary, adjust length of water bars or make small adjustments to
spacing. Do not allow runoff from upslope water bars to converge with
downslope water bar outlets. Construct sediment traps or outlet stabiliza-
tion structures as needed.
Seed and mulch the ridge and channel immediately.
2:1 side slopes or flatter
(3:1 minimum for
Figure 6.23c Imo-- 6'min —�I vehicle crossing)
Cross section of
a water bar. 91,
Slope
A LIIII=I1�11�—i1 +11=1 — min III III —_
IIIIf= III llll=1 II IIil - - ( MIIII -IIIII
I I-=IIIII I F=I Iil ITITg I IIkmI I f I E=
IIIII=Illlil=11111�1 = IIIII =i���l='"„
Common ■ Overtopping ridge where diversion crosses low areas. Build water bars
Trouble to grade at all points.
Points 0 Erosion between water bars—spacing too wide for slope(Table 6.23a).
Install additional water bars.
■ Ridge worn down and channel filled where vehicles cross—surface not
stable or side slopes too steep;may need gravel.
■ Erosion at outlets—install outlet stabilization structure or extend
upslope water bar so runoff will not converge on lower outlets.
■ Erosion in channel—grade too steep. Realign water bar.
6.23.3

Right-of-Way Diversions 0
Maintenance Inspect water bars periodically for vehicle wear. Inspect for erosion and
sediment deposition after heavy rains.
Remove debris and sediment from diversion channel and sediment traps,
repair ridge to positive grade and cross section. Add gravel at crossing
areas and stabilize outlets as needed.
Repair and stabilize water bars immediately if right-of-way is disturbed
by installation of additional utilities.
In removing temporary water bars,grade ridge and channel to blend with
natural ground. Compact channel fill and stabilize disturbed areas with
vegetation. Water bars should not be removed until all disturbed areas
draining to them have been stabilized,inspected,and approved.
If water bars are designed for permanent use, correct any erosion prob-
lems,stabilize outlets,and apply permanent seeding.
6.23.4

Prucriee Sfarndurds and Specifrcutions
6.83
Definition A small t—porary stone darn constructed across a drainaSe way-
Purpose To reduce erasion in a drainage chartmi by reducing the velocity of flow.
Conditions Where This practice may be used as atemporary nwasnre to limit erosion by reducing
Practice Applies
vehxity in small open channels. Wlien needed,they can be used in charmels.
roadside ditches.and temporary dnersiwrs.
Check darns tray be used to,
rrducc voloci y in anall ttmportry c]mammcts that are dcgroding, but
where permanem stabilization is knpractical due to their slk&t period of
usefi►lness;
reduce velocity in small eroding charnels where construction delays or
weather conditions prevent timely installation of nonerusive Liners.
Do not use check dams I intermittent or perennial streams.
Planning Check dates are an expedient wav to reduce Sullying in the hottotrt of ebannels
Considerations that will be filled or stabilized at a later date. The dates should only be used
while permanent stabilization measures are being put into place.
Check dams installed in grass-lined channels may kill the vegetative lining
if subme Bence after it rain is too long arh&or silting is excessive- All crone
and riprap must be removed if mowing is planned as part of vegetative
mainteuattce.
Design Criteria The following criteria should be used when designitip,a check darn,
e The drainage area is limited to one half acre-
Keep a m;L dmum betght of 7 feet at rho center ofthe dam-
e K-aep the center of the dreck darn at lean 9 inebes lower than the nuter
edges at natural ground elevation.
Keep the side slopes of the dam ar'_:1 ur Halter.
•F)sure that the maximum spacing between dams places the toe of the
upstream dam at the same elevation as rite top of the downstream darn
(Figure 6.133a).
Stabilize outflow areas aloasg the channel to resist
erosion-Um NC DOT Class B stone and line the upstream side of the dam with
NC DOT#5 or#57 stone.
Key the stone iuto the ditch banks and extend it beyond the abutmcuts a
minitnurn of 1.5 tcet to avoid washouts from overilaw around the dam.
ken-N06 6693.1

Construction I. f l.tt,c~cafe to the lines and dimerlsm m show it in the plan on a filter fabric
Specifications feur]daFLo[k.
2. Keep the center Simle seetroa at least 4 inches below natural around level
wlkm the darn abuts the channel banks-
3. Emend siege at least 1-5 feel beyond the ditch bank ifigure 6.83bh to keep
wafer 1'rwn l:U0115 arF Und r1Lc erLds of doe check daorL-
4. Set spacing between dance m assure tlud the An ation at the top of the
lower damn is tlke same as die toe elevation of the upper darn.
5. Protect(Ike chamel after the lowest check dano From heavy flaw that could
cause efosion-
6. Make sure that the chasmei:,each above the moll upstream darn is stable-
r. Ensure that otter areas of the channel,such as eulvert entrances below the
check dams-are not subject to damage or blockage from displaced stoa&,
L = The distance SWCh that point$
A and B are of equal elevation
A B
- , - L i
_m
Flguro 9-839 Soac9 check damn in a dha mei c❑1haL mhe vest of downytWm dam i5 et ebvauon of the toe of llps"am dnm

Practice Viandnrds mid.Spccrfeadajus
I. min
9"min
`-
----------- -------_--
� K
Filter Cloth
Phan View
12`of NC1aOT 7F5 or xt57
washed Stone � l,5
Class 9 RlpNp
?l
2'Max.at
center
� 1
Fltgr Cloth
Aa
4 to ti'
Cross-Seeflon View
Figure 45.A31i SLona check Cam stone should he piacad over the channel hanks to keep watarfium rmtLieg armKd the
cam.
Maintenance lnspeet checkdamsandche els atlmstweekly and after�h signi[i�t[E;3
inch or grcstui Tatat'all event and repair immediately. ULcan out MAMent
straw.limbs,or other debris that could elag the channel when ureded_
Amiciptde submcrgencc aaddepostnan abovtthc check dam andemsLon t'rom
high Howl mrm d the edses Lvf Lhe dam. t=orrret all damage immediately. if
arptficant emsmn occurs betwaen dams,additional measurns=be taken
such ar4 installing a protective nprsp]erne to that pertiun of[be cimanel
Wmnice 6.3I,Ritwgq 4irre nerd P�++rd{hernrelsl.
manors scdtmcnt accumuLa Led bchmd tlkr dams as needed to prevent damage
to channel vege[a[mn.allow[he channel In drain tbroegh the s[oncchmk dam.
and prevent large Hrrxx from carrvtng xedtmern orcr Lbe dam. Add atonoe to
dams as receded to mamtarn design hngh[and crags scetton.
Re%renees F4 wfV cOnv&J n ltdeaT"eeE
6.30.Gress-lined Channels
&3 L,Riprep-hued and Ptrved Chnanels
.V'[trHi C'arrMira 2}erxnrarkrijl of rrtuagwrralirra
Standard 5peclfeuationc for Roads and Structure&
R—moo- 6.113.3