EPA-908/3- 80-001 B
Volume 2: Nonpoint Source Control Techniques
UPPER EAGLE VALLEY
NONPOINT SOURCE ASSESSMENT
AND CONTROL PLAN
FEBRUARY 1980
PREPARED FOR
U.S. Environmental Protection Agency
Region VIII
BY
ENGINEERING-SCIENCE, INC
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UPPER EAGLE VALLEY
NONPOINT SOURCE ASSESSMENT
AND
CONTROL PLAN
Volume 2: Nonpoint Source Control Techniques
Prepared for the
U.S. Environmental Protection Agency
February 1980
by
Enginee ring-Science
125 West Huntington Drive
Arcadia, California 91006
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DISCLAIMER
.This.report has been reviewed by .the U.S. Environmental Protection Agency,
and approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the UJ3. Environmental Protection
Agency, nor does mention of.trade names or conraercial products constitute endorse-
ment or reconmendation for use.
Document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
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INTRODUCTION
This volume of the Upper Eagle Valley Nonpoint Assessment and Control
Plan contains information and descriptions of nonpoint source control tech-
niques which can be employed in the Upper Eagle Valley. This information
is based upon an extensive review of literature, consultations with per-
sons knowledgeable in the field, an analysis of the types and sources of
nonpoint source pollution within the Upper Eagle Valley, and the experi-
ence of Engineering-Science, Inc. Three published references provided the
basis for much of the information presented. These references, listed
below, are recommended for inclusion in the library of any individual or
organization concerned with nonpoint source control.
A. Lake Tahoe Basin Water Quality Plan, Volume II - Handbook of Best
Management Practices, Tahoe Regional Planning Agency, January 1978.
B. A Guide for Erosion and Sediment Control in Urbanizing Areas of
Colorado, U.S. Department of Agriculture Soil Conservation Service,
Denver, Colorado, Interim Guide Undated, circa 1978.
C. Standards and Specifications for Soil Erosion and Sediment Control in
Developing Areas, U.S. Department of Agriculture Soil Conservation
Service, College Park, Maryland, approved by the Water Resources Ad-
ministration, Maryland Department of Natural Resources, July 1975.
The control techniques presented and the information contained in the
cited references cannot substitute for good project planning. They can
only mitigate the consequences of bad planning. In concert with good
planning and enforcement, they can greatly reduce nonpoint source pollution
problems. Planning aspects are addressed in Section VII, Volume 1 of this
report. Enforcement requires training and experience. While the informa-
tion presented in this report provides general and specific guidance, short
courses, workshops and actual field experience are required for anyone
responsible for enforcement.
DESIGN STORM - CONSTRUCTION PERIOD
The design storm to be used in the design of various facilities for
runoff and erosion control as described in several control techniques
is the 10-year, 6-hour duration rainstorm. The total rainfall for this
design storm is 1.3 inches. The 10-year return period was chosen be-
cause there would be a 20 percent chance that this storm would occur
during any two-year period. This risk is considered acceptable during
the presumed two-year construction and recovery period of most develop-
ment projects.
The total rainfall of 1.3 inches for a 10-year, 6-hour duration storm
applies to storms occurring during the months of May through October,
precipitation is presumed to be in the form of snow the remaining months,
and in the developable portions of the study area i.e. the valley floors.
The source for this data Is:
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Miller, J. F., Frederick, R. H., and Tracey, R. J., Precipitation -
Frequency Atlas for the Western united States - Vol. 3, Colorado,
NOAA Atlas 2, 11 volumes, 1973.
Rainfall varies significantly within the study area, and is strongly de-
pendent upon altitude. Therefore, the above reference should be consulted
to determine design storm total rainfall for development at altitudes above
8,400 feet.
FROST DEPTHS
Several nonpoint source control techniques depend upon infiltration
of runoff to reduce stream pollution. If operation during periods when
the ground is frozen is required, facilities must be designed accordingly.
Frost depths in the upper Eagle Valley typically range from 3 to 5 feet
with depths as great as 6 or 7 feet recorded in some cases. The depth
of frost penetration is dependent on altitude, where lower air tempera-
tures occur, and on exposure to sunlight. Site investigations or consul-
tations with the county/town engineer may be used to determine the appro-
priate frost depth. In some instances, the cost of installing infiltra-
tion facilities below the frost line may be avoided by employing other
control techniques for runoff when the ground is frozen.
ORGANIZATION OF INFORMATION
The remainder of this volume is divided into four parts which pre-
sent four types of nonpoint source control techniques. These are:
Part 1 - Temporary Runoff Control Measures, Techniques A through D
Fart 2 - Permanent Runoff Control Measures, Techniques Q through V
Part 3 - Temporary Slope Stabilization and Revegetation Measures,
Techniques W through GG
Part 4 - Permanent Slope Stabilization and Revegetation Measures,
Techniques HH through LL
A list of control techniques is provided on the next page for quick
reference.
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ENGINEERING -SCIENCE
FART 1
TEMPORARY RUNOFF CONTROL MEASURES
ES
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LIST OF CONTROL TECHNIQUES
Part 1 Temporary Runoff Control Measures
A Diversion Dike
B Stabilized Construction Entrance
C Runoff Interception Trench or Swale
D Level Spreader
E Filter Berm
F Filter Fence
G Sandbag Sediment Barrier
H Siltation Berm
I Filter Inlet
J Flexible Downdrain
K Pipe Drop
L Chutes and Flumes
M Stone Outlet Structure
N Sediment Trap
0 Sediment Retention or Flow Detention Basin
P Check Dams
Part 2 Permanent Runoff Control Measures
Q Dry Well
R Parking Lots and Service Aprons
S Dripline Trenches
T Storm Drains
U Discharge Apron and Armored Scour Hole
V Short Term Ponding
Part 3 Temporary Slope Stabilization and Revegetation Measures
W Hydromulching
X Wood Chip Application
Y Fiberglass Roving
Z Straw Mulch
AA Crushed Stone and Gravel Mulches
BB Jute Matting
CC Wood Excelsior Matting
DD Installing Matting in Drainage Channels
EE Chemicals and Tackifiers
FF Native Rock Retaining Wall
GG Gabions
Part 4 Permanent Slope Stabilization and Revegetation Measures
HH Wattling
II Slope Bottom Bench
JJ Slope Serration
KK Slope Stepping
LL Vegetative Stabilization
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CONTROL TECHNIQUE A
DIVERSION DIKE
DEFINITION
A runoff interceptor constructed at the top of cut or fill slopes.
PURPOSES
To divert overland flow away from slopes and reduce uninterrupted slope
length.
APPLICABILITY
All slopes which may receive runoff from upslope areas. Generally used
during construction to divert runoff from graded or disturbed areas.
Normally one of the first erosion control measures Installed at a con-
struction site. May be incorporated into final site design to divert
large or polluted flows from the site.
PLANNING CRITERIA
Diversion dikes shall be placed to intercept all runoff flow from above
cut and fill slopes to prevent collected runoff from flowing onto slope
faces below.
« The drainage area should generally be less than five acres.
« Recommended design is shown in Figure A-l.
® Diversion outlet must be to heavily vegetated or artificially
stabilized areas or to a downdrain, chute, or flume.
8 Diverted runoff shall not overtop the dike.
° General criteria include:
• Height - 1.5 feet or greater.
• Top Width - 2 feet.
• Side Slopes - 2:1 or flatter
0 Compaction - Should be 85 percent of maximum density.
• Grade - Dependent upon topography—must be positive.
For grades in excess of 2 percent or large flows,
the diversion channel requires mechanical stabili-
zation with a concrete, asphalt, or riprap lining.
Flows concentrated by the diversion dike shall be
conveyed from the slope using chutes, flumes, or
pipe drops.
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a Discharge - Discharge shall be to heavily vegetated natural
forest area, mechanically and/or vegetatively
stabilized area, or drainage system.
METHODS AND MATERIALS
° The diversion dike consists of a trench and a dike. The trench
shall be constructed using a dozer blade or hand tools. The dike
shall be compacted as specified above.
° In wooded areas where top of slope access is limited and antici-
pated interception of runbff will produce very small flows, diver-
sion dikes can be constructed as a dozer finishes the slope by
carrying soil upslope and dumping it at crest. Compaction is
sacrificed in this instance. A larger dike is necessary to partially
compensate for lack of compaction.
MAINTENANCE
Inspect after each major storm to locate any damaged areas. Repair must
be completed before next storm. Any channel obstructions shall be re-
moved.
COST
The unit cost for a diversion dike ranges from $3.50 - $4.50 per lineal
foot.
STANDARD SYMBOL
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2' min.
Natural ground line
2:1 slopes or flatter
Cut or fill slope
SECTION
not to scale
2' min.
Natural ground line
SECTION
Dike constructed by dozer moving soil
upslope and dumping at top of slope.
Diversion dike to be constructed at top of cut or fill slope.
Outlet to stabilized area.
DIVERSION DIKE
FIGURE A-l
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CONTROL TECHNIQUE B
STABILIZED CONSTRUCTION ENTRANCE
DEFINITION
A temporary pad of crushed stone located wherever traffic accesses the
construction site from a public right-of-way.
PURPOSE
To reduce or eliminate the tracking or flowing of sediment onto public
rights-of-way.
APPLICABILITY
All construction site entrances or exits. Normally one of the first
erosion control measures installed at a construction site.
PLANNING CRITERIA
Stabilized construction entrances shall be placed at all points of con-
struction site vehicle access to control the tracking or flowing of
sediment onto public rights-of-way.
a The recommended design is shown in Figure B-l.
9 Drainage from the stabilized construction entrance may have to be
augmented with sediment traps, filter berms, etc. to prevent
polluted runoff from entering drainage ways, storm drains, and
streams.
• General criteria include:
0 Length - not less than fifty feet
0 Width - not less than width of entrance
° Depth - not less than eight inches
9 All sediment tracked, washed, spilled or dropped on public
rights-of-way must be removed immediately.
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METHODS AND MATERIALS
Use washed crushed rock (1" - 2-1/2") containing less than five percent
fines
MAINTENANCE
Periodic top dressing may be required with additional stone as required.
Auxiliary measures to trap sediment may have to be occasionally cleaned
out« Inspect after each storm and at end of snowmelt period.
COST
Approximately $14 per lineal foot for twenty-foot wide surface.
STANDARD SYMBOL
ms3$|
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Existing ground
50' min.
Public
Right-ef-Way*
8 mm
Provide appropriate transition
PROFILE bttwtsn Stabilized Construction
111 Entrance and Public Right-of-Way
Existing
ground
50* min.
PLAN
not to seal*
Public
Right-of-Way
STABILIZED CONSTRUCTION
ENTRANCE
FIGURE B-l
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CONTROL TECHNIQUE C
RUNOFF INTERCEPTION TRENCH OR SWALE
DEFINITION
A trench or swale constructed along contours of slopes.
PURPOSE
To decrease the uninterrupted slope length, store and divert surface
runoff from the slope face to reduce the erosion potential from con-
centrated surface runoff.
APPLICABILITY
Used on slopes with comparatively gentle gradients (3:1 or less) but
having long uninterrupted slope lengths; e.g., abandoned dirt roads,
easements, and gently sloping cuts and fills.
PLANNING CRITERIA
The recommended design is shown in Figure C-l. Construct the trench
along the slope contour with outlet to a level spreader or other stabi-
lized discharge. Excavated material shall be placed on downslope side
of trench and spread to conform with the natural slope. The trench and
the surrounding slope shall be stabilized and revegetated immediately
after construction.
0 Drainage Area - less than five acres.
• Depth - 12 inches at the downslope edge,
o width - 13 Inches at the bottom
a Side Slopes - 2:1 or flatter
• Grade - 2 percent slope away from slope centerllne to stabilized
discharge or drainage facility.
o Trench or Swale Spacing - Spacing shall be determined using the
following criteria:
Slope more than 20% 10-202 5-10% less than 5%
Maximum dis-
tance between SO feat 100 feet 200 feet 300 feet
trenches or
swales
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MAINTENANCE
Inspect for damage after spring snowmelt and each major storm. Repair
damage immediately as required.
COST
The unit cost for a runoff interception trench or swale is $5 - $7 per
lineal foot.
STANDARD SYMBOL
Runoff Interception Trench
Runoff Interception Swale
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Rmnovcd forth to bt
spread or disposed
min.
INTERCEPTOR SWALE
min.
S N
N"ur"
min.
INTERCEPTOR TRENCH
ISOMETRiC SECTIONS
RUNOFF INTERCEPTOR
TRENCH OR SWALE
FIGURE C-
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CONTROL TECHNIQUE D
LEVEL SPREADER
DEFINITION
An outlet constructed at zero grade across a slope to disperse con-
centrated runoff.
PURPOSE
To convert concentrated flow Into sheet flow for outlet at noneroslve
velocities onto areas stabilized by vegetation.
APPLICABILITY
Used at locations where concentrated runoff from unstabilized areas
can be diverted onto stabilized areas under sheet flow conditions;
e.g., at diversion dike or runoff interception trench outlets.
PLANNING CRITERIA
Detailed design is not required, but extreme care must be used during
construction to ensure that the outlet lip is exactly level and uni-
form from end to end (Figure D-l). Failure to meet these requirements
will cause concentrated flow and consequent erosion of the stabilized
area. The excavation for the spreader must be on undisturbed soil
(not cut or fill) and be well stabilized.
8 Level spreaders shall not be located on slopes steeper than 3:1.
General criteria include:
o Depth Below Level Lip - At least 0.5 feet.
• Length - 15 lineal feet minimum for each 0.1 cfs of discharge.
® Width - At least 6 feet from centerline to level lip.
• Back Slope 2:1 or flatter.
• Material - Must be constructed in undisturbed soil and must
outlet into a stabilized area.
o Inflow - Runoff to the spreader must be from areas which have
have been stabilized to eliminate sediment buildup
in the spreader.
o Discharge -When discharge is to a slope steeper than 4:1 or the
soil is highly erodible, the length of the spreader
shall be increased and slope stabilization methods
shall be installed on the discharge lip to ensure
the stability of the discharge area.
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MAINTENANCE
Inspect for damage after each storm. Repair as required. Remove sedi-
ment as necessary.
COST
The unit cost for level spreaders is $2 - $4 per lineal foot.
STANDARD SYMBOL
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Extend Diversion Dike
at least 2' beyond disturbed
area into stabilized area
Undisturbed soil stabilized with vegetation.
Repair areas damaged during construction.
Undisturbed
no
LEVEL SPREADER
FIGURE D-l
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CONTROL TECHNIQUE E
FILTER BERM
DEFINITION
A filter berm is a temporary ridge of gravel or crushed rock.
PURPOSE
To retain sediment on-site by retarding and filtering runoff while
allowing water to be discharged from the site.
APPLICABILITY
Filter berms may be used as outlets for sediment barriers around con-
struction sites, where graded areas meet paved roadways, in uncompleted
drainage facilities, or any other location requiring detention and
filtration of runoff water.
PLANNING CRITERIA
Filter berms are used to filter runoff water for discharge from the
site. Continuous filter berms may be used around construction sites
or individual berms may be located at discharge points in impermeable
barriers such as shown in CT G&H.
0 If continuous filter berms are used, discharge through shall
be to a stable area such that no erosion occurs.
0 Detailed design is not required. Figures E-l and E-2 provide
general design criteria. Minimum requirements for use on graded
rights-of-way are as follows:
0 Height - 1.5 feet to 3 feet.
0 Top Width - 1 to 1.5 feet.
• Side Slopes - 2:1 or flatter
° Material - Coarse (3/4" to 1-1/2"), well-graded gravel or
crushed rock. Fines less than 5 percent.
0 Filter Cloth - As specified in CT F.
MAINTENANCE
Remove all trapped sediment and clean out or replace clogged filter
material after each storm. Repair as damaged by traffic.
COST
The unit cost for filter berms is $6.00 - $7.00 per lineal foot.
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STANDARD SYMBOL
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1.5" TOP WIDTH
GRAVEL OR CRUSHED ROCK
TYPICAL
MIN.
FILTER CLOTH
SECTION
NOT TO SCALE
CONSTRUCTION SITE
BOUNOARY
FLOW
FLOW
IMPERMEABLE
BARRIER
FLOW
IMPERMEABLE
BARRIER
t FILTER BERM OUTLET
DISCHARGE TO STABLE
DRAINAGE
typical, filter berm
PLAN
NOT TO SCALE
FIGURE £-(
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—
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CONTROL TECHNIQUE F
FILTER FENCE
DEFINITION
A low fence made of filter cloth and fencing material.
PURPOSE
To filter runoff water prior to discharge.
APPLICABILITY
Any construction site or other site of disturbance where the danger of
discharge of sediment-laden water exists. This is a temporary measure
and should be removed when no longer needed.
PLANNING CRITERIA
A filter fence can be substituted for a filter berm at approximately
equal cost, but the filter fence is easier to maintain and remove.
Care must be taken to insure that all runoff water must pass through,
not over, under or around, the filter cloth. This only applies to
sites which will not be subjected to significant hydrostatic pressure
or to vehicular traffic.
METHODS AND MATERIALS
o The filter fence shall be designed to filter the design storm
without overtopping, collapsing, becoming sedimented in, or
being skirted by runoff flows.
• The fence shall be constructed with fence posts and "hog-wire"
(4"x4" or 6"x6" wire mesh) or "chicken-wire" of #14 or heavier
gauge wire. The fence shall be constructed as shown in Figure F-l.
• A trench shall be excavated at the uphill base of the fence to
a depth of at least 6 inches.
° Filter cloth (Mirafi 140 or equivalent) shall be draped over the
wire fencing material and lowered into the trench.
a The trench shall be backfilled to grade and compacted.
MAINTENANCE
Inspect periodically and after each storm for damage and repair or re-
place damaged sections. Remove sediment accumulations when the capacity
of the filter is impaired.
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COST
The unit cost for a filter fence is $2.30 to $2.70 per lineal foot.
STANDARD SYMBOL
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I. Drive wooden or mstol posts. 2. Dig too trsnch.
3. Attach wlr* mash.
4. Cut longth of filter fabric.
5. Attach ftltsr fabric.
6. Backfill trsnch.
FILTER FENCE
FIGURE F—l
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CONTROL TECHNIQUE G
SANDBAG SEDIMENT BARRIER
DEFINITION
Temporary sediment barriers or diversions that are constructed of sand-
bags.
PURPOSE
The barriers are built to retain sediment on site by slowing storm run-
off and causing the deposition of sediment at the structure.
APPLICABILITY
Sandbag sediment barriers are used at storm drain inlets, across minor
swales and ditches, and for other applications where the structure
is of a temporary nature. Sandbag barriers do not provide filtration.
They therefore can be used only for minor flows.
PLANNING CRITERIA
Sandbag sediment barriers are used as training berms to direct or
divert runoff flows, or as barriers to collect and store runoff. The
following information pertains to the installation of sandbag sediment
barriers.
o Install so that flow under or between bags la prevented.
e The sandbags shall be stacked in an interlocking fashion to
provide additional strength for resisting the force of the
flowing water.
» Sandbags shall not be stacked more than three high without broad-
ening the foundation using additional sandbags, or providing
additional stability.
0 Sandbag sediment barriers shall store the runoff from design
storm as specified.
MAINTENANCE
Inspect after every storm and replace damaged bags. Clean out trapped
sediment after each storm.
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COST
The unit cost for a sandbag sediment barrier is $3.00 - $3.50 per lineal
foot.
STANDARD SYMBOL
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CONTROL TECHNIQUE H
SILTATION BERM
DEFINITION
An impermeable barrier around construction sites.
PURPOSE
To capture and contain runoff from a construction site, to allow sedi-
ments contained in the runoff to settle out, and to direct runoff
water through filter berms on outlets to stable drainages.
APPLICABILITY
Siltation berms shall be placed on the downslope sides of construction
sites.
PLANNING CRITERIA
Berms shall be sized to contain the runoff water from the design storm.
METHODS AND MATERIALS
Siltation berms shall be constructed of the following materials:
8 3/4 to 1-1/2 inch gravel, or coarse soil material from the site,
if available.
» Plastic sheeting, 6 mil thick, VisqueenR or equivalent, in widths
great enough to cover the berm and allow 2 feet of additional
plastic sheeting on each side of the berm.
The construction procedure shall be as follows:
o The berm shall be located along the contour of the slope at the
downhill margin of the construction site using a hand level.
It shall be marked using stakes, lime lines, or other appropriate
method.
• All trash, debris, forest duff, and materials which could lead
contained stormwater under the berm shall be removed from the
location the berm is to occupy.
9 Gravel or coarse soil material shall be mounded into a ridge of
sufficient height to contain the specified volume of stormwater.
The sides of this ridge shall not exceed 2:1 slopes.
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O Plastic sheeting shall be placed over the berm so that it over-
laps equally on either side of the berm. Where one sheet of
plastic ends and another is begun, the overlap of the ends shall
be at least 4 feet.
« Plastic sheeting shall be anchored with 1-1/2 inch or 3/4 inch
gravel, not coarse soil material. Gravel shall be placed on the
edges of the plastic sheeting to a depth of at least 3 inches
and a width of at least 8 inches (refer to Figure G-l).
MAINTENANCE
Siltation berms shall be inspected periodically and maintained or re-
paired in a manner sufficient to meet the intent of this Best
Management Practice.
COST
The unit cost for siltation berms is $7.00 to $8.00 per lineal foot.
STANDARD SYMBOL
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PlMtic Sheeting
Grovtl
Slop*
.8 win.
Grovtl
ancnor i
rfljfwfftk 3 min.
min.
ELEVATION
min.
SILTATION BERM
FIGURE H-l
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CONTROL TECHNIQUE I
FILTER INLET
DEFINITION
A filter inlet is a temporary filter of gravel or crushed rock placed
at storm drain inlets.
PURPOSE
Filter inlets retain sediment from runoff water prior to discharge
into storm drains.
APPLICABILITY
Filter inlets are used at storm drain inlets which receive runoff
from upstream construction sites.
PLANNING CRITERIA
Specific design is not required.
° Several different design concepts are in use and the configura-
tion of the gravel inlet will depend on the type of inlet being
protected.
° The design uses a filter berm as shown in CT E around the
inlet structure. Alternatives utilize concrete building
blocks to keep berm material from entering the storm
sewer (Figure 1-1).
0 All filter material should be coarse (3/4" to 1-1/2"), well-
graded gravel or crushed rock. Fines should be less than 5
percent.
• Filter cloth shall be placed inside the filter bed as shown in
Figure 1-1. Enough aggregate must be used to insure complete
contact between the filter cloth and the underlying surface.
MAINTENANCE
Remove trapped sediment after each storm and replace clogged filter
material as needed.
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COST
The unit cost for a filter inlet is $1.80 to $2.00 per lineal foot.
STANDARD SYMBOL
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Std. 8 * 8 x 16 Cone. Masonry Blocks
Filter Material
Drainage Inlet
(at sump only)
ISOMETRIC
no scale
Cone. Block
Filter Cloth
Gravel
SECTION 'A-A'
FILTER INLET
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CONTROL TECHNIQUE J
FLEXIBLE DOWNDRAIN
DEFINITION
A conduit of heavy-duty fabric or other flexible material used as a
temporary drain to convey water down the face of a slope.
PURPOSE
To convey surface runoff down cut or fill slopes or other steep areas
to stable discharge points during construction.
APPLICABILITY
Where runoff water accumulates above cut or fill slopes or slope benches
and must be conveyed over the slope.
PLANNING CRITERIA
Flexible downdrains should be installed on slopes immediately after con-
struction and before revegetation of the slope or permanent installa-
tion of drainage facilities.
Specific design is not usually required (see Figure J-l).
« Drainage area must not exceed five acres.
« Place drains on undisturbed soil or well-compacted fill.
o The diameter should be sufficient to convey runoff from design
storm.
• Standard metal end sections shall be used.
° Extension collars are 12 inches long, corrugated metal pipe of
the proper diameter. Do not use helical pipe.
° Flexible conduit shall be secured to extension collars with
securing straps of fabric, metal, etc., covering at least two
corrugations of the extension collar.
» Flexible downdrains shall be designed for the peak runoff from a
2-year, 2-hour storm.
° Downdrains should be staked down with metal "T" pins spaced
every 10 feet.
a Discharge shall be to an energy dissipator or other stabilized
outlet
o No material shall be placed on collapsed drain.
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MAINTENANCE
0 Inspect for damage or clogging after each storm.
° In below-freezing weather, check to ensure that sides of collapsed
downdrain are not frozen together.
° Inlet section should be checked periodically for indications of
piping along metal sections.
° Resecure anchors and conduct repairs as necessary.
COST
The unit cost for a flexible downdrain is $7.00 to $8.00 per lineal foot
for 250-300 feet of installed downdrain.
STANDARD SYMBOL
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FLEXIBLE OOWNORAIN
ISOMETRIC
OISCHAR0E TO
STABILIZED WATER
COURSE OR ARMORED
SCOUR HOLE
TOP OP DIVERSION DIKE
STANDARO METAL ENO SECTION
FLEXIBLE DOWNDRAIN
FIGURE J
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CONTROL TECHNIQUE K
PIPE DROP
DEFINITION
A pipe from the top to the bottom of a slope.
PURPOSE
To convey surface runoff down a slope to prevent erosion of the slope
face.
APPLICABILITY
To convey runoff gathered by diversion dikes, infiltration trenches,
horizontal steps, or other surface runoff control facilities.
PLANNING CRITERIA
The conveyance of water in a stabilized system from the top of a slope
to the bottom is necessary to prevent erosion and to ensure slope
stability and the success of revegetation efforts. Inadequate place-
ment or maintenance of pipe drops can result in the failure of both
the pipe drop and the slope stabilization and revegetation.
0 The basic design for a pipe drop is shown in Figure K-l.
• Detailed design for pipe drops oust be obtained and
caution must be used in construction to prevent runoff
water from avoiding the pipe drop and flowing down the
face of the slope.
• Pipe drops must not drain more than five acres.
Temporary pipe drops shall be designed for the peak run-
off from a 5-year, 6-hour storm.
• Pipe drops shall be designed for the peak runoff from a
50-year, 24-hour storm.
0 Stable inlet and outlet structures must be provided.
• The pipe drop inlet shall be constructed of concrete.
» Outlet protection shall be provided by riprap or other
means of energy dissipation.
o Thrust blocks shall be placed at all grade changes
o Antiseep collars shall be placed at intervals no greater
than 20 feet along the pipe drop.
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° The inlet structure shall be designed for the design storm
with a safety factor of 1.5 to prevent overtopping of the
slope.
° The pipe drop shall be constructed in the slope using adequately
compacted backfill.
° Concrete or riprap shall be installed at the inlet and outlet
as necessary to prevent soil erosion.
MAINTENANCE
Inspect for damage or clogging after each major storm. Inlet section
should be inspected periodically for indications of piping.
COST
Cost estimates for pipe drops are not available but should be on the
order of $12.00 to $14.00 per lineal foot.
STANDARD SYMBOL
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CONCRETE
INLET \
21 OR FLATTER SLOPE
'ANT1 - SEEP COLLAR
OUTLET
CONCRETE ON
RIPRAP
UNOrSTURBED SOIL
OR COMPACTED FILL
CONCRETE THRUST
BLOCK
NOTE> Rip.rap shall b« 6" lay«rof 4" min. dm*n»ion rock or rubblt with 3" toml Mding.
PIPE DROP
FIGURE K-l
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CONTROL TECHNIQUE L
CHUTES AND FLUMES
DEFINITION
Concrete channels designed to conduct runoff down a slope face.
PURPOSE
To convey surface runoff down a slope face without erosion.
APPLICABILITY
Permanent structures down slopes where concentrated runoff would cause
slope erosion. They can be used to convey runoff from diversion dikes,
infiltration trenches, slope steps, benches, or other runoff control
facilities.
PLANNING CRITERIA
Chutes or flumes are used to convey water collected above a slope
down the slope without causing erosion. These structures shall be
made of durable material and shall be designed with adequate capacity
to convey the 50-year, 6-hour storm, by a registered civil engineer.
Detailed design is required.
® The basic design of chutes or flumes is shown in Figure L-l.
0 Chutes or flumes shall be placed on undisturbed soil or well
compacted fill.
° Slopes shall be no steeper than 2:1 (horizontal to vertical)
nor flatter than 20:1.
0 The elevation at the top of the lining of the inlet structure must
not be higher in elevation than the lowest elevation of training
berms or other devices that direct flow to the chute or flume.
° To insure that a good bond is attained at the Interface of the
structure and training berms and to prevent piping failure,
soil must be compacted around the inlet.
« The outlet structure shall be protected against scour with chute
blocks, impact basin, rock riprap revetment, or plunge pool.
8 The outlet shall be to stabilized area or stable drainage
system.
-------
MAINTENANCE
Inspect for damage after each major storm. Inspect for signs of piping
failure at interface of entrance structure and training berms. Repair
as needed.
COST
Cost estimates for a concrete flume constructed with pneumatic concrete
reinforced with wire mesh range from $30.00 to $35.00 per lineal foot.
STANDARD SYMBOL
-------
CUT-OFF 'MALL'
2-ROWS, STAGGERED,
MJI l—II
STO. 8x8 x 16
BUILDING BLOCKS
EM8EDCEC HALF-WAY
CUT-OFF WALL
ALTERNATE SECTIONS A-A
CHUTE OR FLUME
FIGURE L—I
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CONTROL TECHNIQUE M
STONE OUTLET STRUCTURE
DEFINITION
A temporary crushed stone dike installed in conjunction with and as a
part of a diversion dike or interceptor dike.
PURPOSE
The purpose of the stone outlet structure is to provide a protected
outlet for a diversion dike, interceptor dike, siltation berm or filter
berm, to provide for diffusion of concentrated flow, and to allow the
area behind the dike to dewater.
APPLICABILITY
Stone outlet structures apply to any point of discharge where there is
need to dispose of runoff at a protected outlet or to diffuse con-
centrated flow for the duration of the period of construction* When
the entire drainage area to the structure is not stabilized, a sediment
trap must be provided in conjunction with the stone outlet structure
(see Control Technique for Sediment or Flow Retention Basins).
PLANNING CRITERIA
A stone outlet structure shall be used only where the contributing
watershed is less than five acres. The minimum length, in feet, of
the crest of the stone outlet structure shall be equal to six times
the number of acres of contributing drainage area. The crest of the
stone dike shall be at least six inches lower than the lowest elevation
of the top of the earth dike and shall be level. The stone shall be
crushed stone. Gravel may be used only if crushed stone is not available.
• The stone outlet structure shall be located so as to discharge
onto an already stabilized area or into a stable watercourse.
Stabilization shall consist of complete vegetal cover, paving,
etc., sufficiently established to be erosion resistant.
• The crest of the stone dike shall be at least six inches lower
than the lowest elevation of the top of the earth dike and shall
be level.
8 Stone of the outlet structure shall be embedded into the soil a
m-tn-tminw of four inches.
8 The minimum length, in feet, of the crest o| the stone outlet
structure shall be equal to six times the number of acres of
contributing drainage area.
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0 The stone outlet structure shall be inspected after each rain, and
the stone shall be replaced when the structure ceases to function
as intended for such reasons as silt accumulation among the stone,
washout and construction traffic damage.
MAINTENANCE
Inspect for damage after each major storm. Clean out trapped sediment
and repair as needed.
COST
The unit cost of a stone outlet structure Is $8.00 to $9.00 per lineal
foot.
STANDARD SYMBOL
-------
EARTH DIKE, SILTAT10N BERM, OR FILTER BERM
Level crest<
-ii ,
6 mm.
Stone embedded-
(as shown on plan)
min."]
^
3
"ft'"
min.
PROFILE
not to scale
STONE OUTLET STRUCTURE
FIGURE M-l
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CONTROL TECHNIQUE N
SEDIMENT TRAP
DEFINITION
A small temporary basin formed by excavation and/or an embankment to
intercept sediment laden runoff and to trap and retain the sediment.
PURPOSE
The purpose of a sediment trap is to intercept sediment laden runoff
and trap the sediment in order to protect drainage ways, properties, and
rights-of-way below the sediment trap from sedimentation. It is tem-
porary structure and is to be removed once construction is complete and
disturbed areas stabilized.
APPLICABILITY
A sediment trap is usually installed in a drainage way, at a storm drain
inlet, or at other points of discharge from a disturbed area.
PLANNING CRITERIA
The sediment trap should be located to obtain the maximum storage benefit
from the terrain, for ease of cleanout and diposal of the trapped sedi-
ment and to minimize interference with construction activities. For
drainage areas greater than 3 acres see Control Technique for Storm Water/
Sediment Retention Basins.
° The drainage area for each sediment trap shall be less than 3 acres.
° The volume of a sediment trap as measured at the elevation of the
crest of the outlet shall be at least 1000 cubic feet per acre of
drainage area. The volume of a natural basin may be approximated
by the equation; Volume (cu.ft.) m 0.4 x surface area (sq. ft)
x maximum depth (ft).
° All embankments for sediment traps shall not exceed 5 feet in
height as measured at the low point of the original ground along
the centerline of the embankment. Embankments shall have a minimum
4 foot wide top and side slopes of 2:1 or flatter.
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METHODS AND MATERIALS
Embankments shall be compacted by traversing with equipment while it is
being constructed. Fill material for embankments shall be free of roots
or other vegetative material, as well as oversized stones, rocks, organic
or other objectionable material which may cause excessive embankment
seepage or piping. There are two basic types of outlets for sediment
traps. These are pipe outlets and stone outlets. A pipe outlet sediment
trap consists of a basin formed by an excavation and/or an embankment.
The outlet for the trap is through a perforated riser and a pipe through
the embankment. The outlet pipe and riser shall be made of corrugated
metal. The riser diameter shall be of the same or larger diameter than
the pipe. The top of the embankment shall be at least 1-1/2 feet above
the crest of the riser. At least the top 2/3 of the riser shall be per-
forated with 1/2" diameter holes spaced 8 inches vertically and 10-12
inches horizontally. All pipe connections shall be watertight. See
Figure N-l
Select pipe diameter from following table:
Mlninum Pipe Diameter Maximum Drainage Area
A stone outlet sediment trap consists of a basin formed by an embankment
or excavation and an embankment. The outlet for the trap is over a
level stone section. The stone outlet for a sediment trap differs from
that for a stone outlet structure because of the intentional ponding of
water behind the stone. To provide for a ponding area a relatively im-
pervious core (e.g. — timber, concrete block or straw bales) is
placed in the stone. The core shall be covered by 6" of crushed stone.
The minimum length (feet) of the outlet shall be equal to 4 times the
drainage area (acres). The crest of the outlet (top of stone) shall be
at least 1 foot below the top of the embankment. The crushed stone used
in the outlet shall be well graded with a maximum size of 2 inches and
with less than five percent fines. See Figure N-2.
MAINTENANCE
Inspect for damage and repair as required after each storm. Sediment
shall be removed and the trap restored to its original dimensions when
the sediment has accumulated to 1/2 of the design depth of the trap.
Cost estimates for sediment traps are not available due in part to
site specific requirements.
12"
18"
21"
1
2
3
COST
SYMBOLS
There is no standard symbol for a sediment trap.
-------
/C/T / Excavate, if necessary
for storage.
Earth embankment
Outlet protection
All slopes 2:1
or flatter
Perforated riser
5* max.
Welded all around
EMBANKMENT SECTION THRU RISER
PIPE OUTLET
SEDIMENT TRAP
FIGURE N-l
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Excavate, if necessary
for storage.
Cutaway to show
straw bale core.'
Stone
Length(ft.) = 4 X drainage area(Ac)
111 mln.
'.S" ! .'S.!! 1 ^
Ejttend core into _
earth embankment
ELEVATION
Not to scale
STONE OUTLET
SEDIMENT TRAP
FIGURE N-2
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CONTROL TECHNIQUE 0
SEDIMENT RETENTION OR FLOW DETENTION BASIN
DEFINITION
A temporary or permanent dam or basin.
PURPOSE
Used to trap and store sediment contained in surface runoff and to serve
as a flow detention facility for reduction of peak runoff rates.
APPLICABILITY
Small temporary structures can be used to trap sediment in runoff from
construction sites. Larger permanent structures can provide substantial
reduction of peak runoff rates when incorporated into the design of a
storm drainage system.
PLANNING CRITERIA
The example design presented below is applicable for small sediment
basins. This design applies primarily to areas where land grading
operations are planned or are underway, and is used as a temporary
measure until areas above the installation are permanently protected
against erosion by vegetative or mechanical means or as a permanent
structure for small drainage basins. The structure may become part of
the permanent drainage basins. The structure may become part of the
permanent drainage system for the area following completion of con-
struction.
Sediment basins covered by this control technique will be limited to
the following category:
° The water surface at the crest elevation of the pipe spillway
shall not exceed nine feet (91) measured upward from the original
streambed to the crest elevation of the pipe spillway; and the
drainage area shall not exceed fifty (50) acres.
Design
0 See Figure 0-1. Design of the basin shall be based upon the total
drainage area lying upstream, and if permanent, on the future use
of such lands; and must be completed by a professional engineer.
0 For acceptable alternative design techniques, see Reference A or B.
0 Vegetation shall be planted on all embankment slopes, borrow
areas, or any other areas disturbed during construction.
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o Antivortex Device - An antivortex device shall be installed
on the top of the riser. An approved antivortex device is
a thin, vertical plate normal to the centerline of the dam
and firmly attached to the top of the riser. The plate
dimensions are: length = diameter of the riser plus 12 inches
height = diameter of the horizontal pipe.
0 Base - The riser shall have a base attached with a water-
tight connection and shall have sufficient weight to prevent
flotation of the riser. Two approved bases are:
1) A concrete base 18 inches thick with the riser imbedded 6
inches in the base. The base should be square with each
dimension 2 feet greater than the riser diameter.
2) A 1/4-inch minimum thickness steel plate welded all around
the base of the riser to form a watertight connection. The
plate shall be square with each side equal to two times the
riser diameter. The plate shall have 2 feet of stone, gravel,
or tamped earth placed on it to prevent flotation;
Trash Rack - A trash rack consisting of #4 reinforcing bars,
6 inches on center, shall be welded across the top of the
riser.
Antiseep Collars - Conduits through embankments shall be pro-
vided with antiseep collars. All basins shall have a minimum
of one antiseep collar which is rectangular blocking all
potential flow through the backfilled material and extending
to the sides of the barrel trench. The horizontal dimension
shall be a minimum equal to the barrel diameter plus 2 feet.
The bottom side of the antiseep collar shall extend a minimum
of 2 feet below the grade line, and the top side shall extend
1 foot above the barrel.
Emergency Spillway
° The minimum capacity for the emergency spillway will be that
required to pass the peak flow in excess of the design storm.
Where emergency spillways are used, the channel bottom shall
have a minimum width of 8 inches.
o Recommended Design - Two recommended designs are: 1) Dis-
charge over the top of dam or embankment, the spillway
shall be lined with concrete; 2) Earth spillways protected
from erosion by vegetation, rock riprap, or other appropriate
material.
o Mavjmum Allowable Velocity - The maximum allowable velocity
in the exit channel of an earth spillway shall be 6.0 feet
per second.
o Vegetative Protection - Provide for the protection of the
embankment and emergency spillway by vegetative or other
suitable means.
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Storage
° The site should be selected to provide adequate storage for not
less than 0.6 inches of runoff per acre of drainage area. Runoff
calculations shall be by accepted engineering practice- Volume
for trap efficiency calculations shall be the volume below the
emergency spillway crest or pipe spillway crest, if there is no
emergency spillway. When necessary, consideration should be given
either to excavating additional storage capacity to meet these
requirements or to plan for periodic cleanout in order to maintain
the capacity requirements. Where available sites do not lend them-
selves to meeting such design criteria, approval must be obtained
from the Town/County to design and Install a sediment basin with
less storage.
0 Sediment basins shall be cleaned out when the effective storage
capacity drops below 0.3 inch of runoff per acre of drainage area.
The elevation corresponding to this level shall be determined and
given in the design data as a distance below the top of the riser.
0 Storage shall be designed not to produce a public nuisance as an
insect breeding site.
Runoff Computations
a Combined capacity of the pipe and emergency spillways shall be
designed to handle a 50-year frequency storm. Runoff will be
calculated by accepted engineering methods, and should be based
on soil and land cover conditions expected to prevail during
the anticipated effective life of the structure.
Pipe Spillways
o Design the pipe spillway to handle not less than design storm
runoff from the drainage area. The pipe spillway will con-
sist of a perforated vertical pipe or box-type riser joined to
a horizontal conduit (barrel) which will extend through the em-
bankment. The horizontal pipe conduit (barrel) will be a minimum
of 12 inches in diameter. The riser shall be a minimum of 30
inches in diameter with a cross-sectional area of at least 1.5
times the cross-sectional area of the horizontal conduit.
o Crest Elevation - When used in combination with emergency
spillways, the crest elevation of the riser shall be at least
one foot below the elevation of the control section of the
emergency spillway. If no emergency spillway is provided,
the crest elevation of the riser shall be at least three feet
below the crest elevation of the embankment.
o Perforated Riser - The upper portion of the riser shall be
perforated with 1-1/2 to A inch diameter holes spaces 8 inches
vertically and 10 to 12 inches horizontally and staggered.
The perforated portion shall be the top one-half to two-
thirds of the riser. The whole pipe length shall be per-
forated if a gravel filter cone is placed around the bottom
one-third of the riser. Perforations shall be small enough
to not allow the passage of filter material.
-------
Freeboard
Freeboard is the difference in elevation between design high water and
the top of the settled embankment.
0 Minimum freeboard shall be 1 foot for sediment basins with an
emergency spillway and 3 feet for those with no emergency
spillway.
Embankment
0 The embankment shall have a minimum top width of 8 feet. Side
slopes shall be no steeper than 2:1. The maximum fill height
shall be 15 feet.
Information to be Submitted to Town/County
Sediment retention basin designs submitted for review shall include the
following:
0 Specific location of the basin.
0 Plan view of dam and the storage basin.
° Cross-section of dam storage basin, and emergency spillway;
profile of emergency spillway.
° Runoff calculations for the design storm.
« Calculations showing design of pipe and emergency spillway.
Storage computation (stated in acre-feet).
0 Total required (acre-feet).
o Total available (acre-feet).
0 Level of sediment when storage drops below 0.3 inches per
acre of drainage area.
METHODS AND MATERIALS
Site Preparation
0 Areas under the embankment and any structural works shall be
cleared, grubbed, and the topsoil stripped to remove all trees,
vegetation, roots, or other objectionable material. In order to
facilitate cleanout and restoration, it is recommended that the
pool area (measured at the top of the pipe spillway) be cleaned
of all brush, trees, or other debris.
Borrow Areas
° All borrow areas shall be graded, revegetated, and left in such
a manner that they are well drained and not subject to erosion.
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Embankment
° The fill material shall be taken from approved designated borrow
areas. It should be free of roots, woody vegetation, oversize
stones, rocks exceeding 6 inches in diameter, or other objection-
able materials. The embankment shall be raised and compacted to
an elevation which provides for anticipated settlement to design
elevation (allow at least 10 percent for settlement).
° Placement - Areas on which fill is to be placed shall be scarified
prior to placement of fill. Fill materials shall be placed in
6-inch maximum lifts which are to be continuous over the entire
length of the fill and approximately horizontal.
° Compaction - The movement of the hauling and spreading equipment
over the fill should be controlled so that the entire surface of
each lift will be traversed by not less than one tread track of the
equipment or compaction shall be achieved through use of a roller.
Pipe Spillway Installation
° The riser must be rigidly and securely fastened to the barrel and
the bottom of the riser must be sealed (watertight). The pipe
spillway shall discharge at ground elevation below the dam. All
pipe joints must be securely fastened and watertight.
o The barrel shall be placed on a firm foundation to the lines and
grades shown on the plans. Backfill material shall be placed
around the barrel in 4 to 6 inch layers and each layer thoroughly
compacted with suitable hand-operated equipment to at least 2
feet above the top of the pipe and antiseep collars before any
heavy equipment is operated over it.
Emergency Spillway Installation (Lined Earth)
° Spillway shall be lined with 4-inch concrete reinforced with 6x6 -
10/10 wire mesh extending to a minimum of 3 feet down each face of
the embankment. Spillway shall be a minimum of 18 inches deep
with 1.5:1 side slopes.
Structural Backfill
0 Backfill material shall be of the type and quality conforming to
that specified for the adjoining fill material. The material shall
be placed starting at the lowest point of the foundation in 6-inch
maximum lifts and hand compacted to equal or exceed the density
of the adjoining fill. Lifts shall be continuous over the entire
length of the fill and approximately horizontal.
Other
The following general construction criteria are critical to successful
installation and operation of sediment retention basins.
-------
0 Locate the dam to provide maximum volume capacity for silt behind
the structure.
0 Prepare the dam site by adequate clearing of vegetation and removal
of topsoil before beginning dam construction.
° Level the bed for the pipe spillway to provide uniform support
throughout its entire length under the dam.
° Securely and rigidly fasten the collar connecting the riser to the
barrel (as well as collars connecting sections of the barrel) of
the pipe spillway; insure a watertight bottom on the riser; hand
tamp fill under shoulders and around the pipe; insure that the
outlet invert of pipe spillway is not more than one foot above
stream bed.
° Place the fill in not more than 6-inch lifts compacted by construc-
tion equipment. A m-tn-lminn of 2 feet of hand-compacted backfill
shall be placed over the pipe spillway before crossing it with
construction equipment. Fill materials should be free from roots,
woody vegetation, oversize stones, rocks, or other objectionable
material. Frozen material should not be used.
o Construct emergency spillway as per design on undisturbed soil
(not on fill). Design width and entrance and exit channel slopes
are critical to the ability of the emergency spillway to success-
fully protect the dam with a minimum of erosion hazard in the
spillway channel.
0 Stabilize embankment and emergency spillway by slope stabilization
and revegetation.
MAINTENANCE
When trap efficiency drops below 0.2 inch per acre of drainage area,
the sediment basin should be cleaned out to restore its original
capacity.
A routine schedule specifiying personnel, budget, and sediment dis-
posal procedures must be submitted to the permit-issuing authority
prior to plan approval.
Sediment must be disposed of in an area that is shown on the plans,
approved by the permit-issuing authority. Location of the dis-
posal site shall be to prevent its return to the debris basin or
to downstream areas during storm runoff. Disposal areas must be
revegetated immediately upon completion of the basin cleaning.
COST
The cost of sediment retention on flow detention basins are varible
and depend upon drainage area and specific site conditions. Cost esti-
mates are $2,700 for a six-foot high 30-foot long embankment to $4,000
for an eight-foot high 40-foot long embankment.
STANDARD SYMBOL
Not applicable. See information required for review by Town/County.
-------
Revagatctad slop*
3 min.
12 min. top ii sidas
12 min. dia. C.M.P
*^^12" min
Outlet to stabilized drainage
court* with tnergy disaipator
SECTION A-A
not to scait
Anti -Vortex plats
30"dia. p«rf standpip«
—-grovei eon*
Anchor block
PL AN Anti>S««p
Collar Detail
*4 bars at 6"o c.
. welded across top
of standpipe.
2% win.
Reinforced Concrete
Emergency Spillway
PLAN
not to icola
NOTE: See References B & C
SEDIMENT RETENTION BASIN
in Introduction for
acceptable alternative
designs.
FIGURE 0-
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CONTROL TECHNIQUE P
CHECK DAMS
DEFINITION
A small temporary structure placed across small drainage ways or water-
courses .
PURPOSE
Used to reduce or prevent erosion by reducing velocity of flow, promoting
deposition of sediments and stabilizing channel flows. Function similar
to a sediment trap. Frequently one of the first erosion control tech-
niques installed.
APPLICABILITY
Any existing drainage way or watercourse where upstream construction
activities may increase drainage flows or sediment loads. May also be
used In constructed drainage ways until upstream drainage areas have be-
come stabilized.
PLANNING CRITERIA
Existing drainage ways and watercourses should be analyzed to determine
if drainage flows and sediment loads will exceed the basic hydrologic
and water quality criteria. Check dams may provide the additional
measure of velocity control required to prevent drainage way or water-
course erosion, and to reduce the sediment load of flows. Figure P-l
gives an example of one type of check, dam.
0 The check dam must be constructed of erosion resistant material.
0 Overlapping flows should be concentrated near the center of the
check dam.
0 The ends of the check dam should be at an elevation well above the
center.
° Check dams should be well anchored to prevent underflow.
METHODS AND MATERIALS
Check dans must be constructed of concrete, masonry, rock, rock and
earth, wood or other erosion resistant material. Rock, concrete, or
wood structures are best suited for narrow drainage ways, watercourses,
or gullies. Rock check dams should be constructed of well graded rock.
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MAINTENANCE
Maintenance only required if large storm flows damage the structure.
When check dams are removed, trapped sediment should be spread, mulched
and seeded.
COST
The cost of check dams varies with the material used, but normally
vary between $1.50 yo $3.00 per lineal foot.
STANDARD SYMBOL
-------
ROCK CHECK DAMS
FOR DITCHES
FIGURE P-
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PART 2
PERMANENT RUNOFF CONTROL MEASURES
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CONTROL TECHNIQUE Q
DRY WELL
DEFINITION
A gravel-filled pit or trench.
PURPOSE
To store and infiltrate surface runoff.
APPLICABILITY
Dry wells can be incorporated into the design of a drainage system to
reduce runoff volume and downstream system sizing or as isolated and
independent infiltration facilities to eliminate localized flooding or
ponding. Should not be used to control construction runoff because of
limited sediment capacity and high maintenance costs.
PLANNING CRITERIA
Dry wells can provide a very inexpensive means of eliminating isolated
flooding or ponding problems in areas with no existing drainage system.
They can also be designed into a storm drainage system to provide
significant flow reduction and system costs, and to provide a means of
filtering pollutants from low flows. The decision for use should be
based upon soil type and percolation rate, slope, and depth to ground-
water in the project area. General planning and design criteria are
discussed below.
o Dry wells can either be constructed as a gravel-filled pit or
trench. Selection of the appropriate type should be based upon
soil depth and permeability and level of groundwater in the
project area.
9 Pit type dry wells can be easily dug using an auger with a
standard size hole 18 inches in diameter.
0 Dry wells should penetrate at least 3 feet below the expected
maximum depth of soil freezing.
° Several shallow dry wells more efficiently infiltrate water than
one deeper well. Deep wells may be necessary where space limita-
tions prevent use of multiple small wells.
° Trenches due with backhoes provide more bottom surface area than
augered holes. Trenches shall shall excavated to at least 3 feet
below the expected depth of soil freezing.
-------
0 Dry wells can be incorporated into the design of catch basins and
integrated into a drainage system to reduce the required capacity
of necessary runoff conveyance facilities.
0 When incorporated into a catch basin, the dry well shall be equip-
ped with an easily accessible cleanout for removing accumulated
sediments and trash as shown in Figure Q-l.
° The dry well shall be filled with 1-1/2 inch to 3-inch rock to
within 6 inches of the desired grade.
0 A blanket of filter cloth (Mirafi 140 or equivalent) shall be
placed over the rock, and clean sand or smaller gravel shall be
backfilled to grade.
0 Typical sections are shown in Figure Q-l.
° See also Control Technique R-Parking Lots and Service Aprons for
various applications.
MAINTENANCE
Inspection during each major rainfall and snowmelt runoff is mandatory
to determine whether the facility is operating. Dry wells associated
with catch basins require periodic cleaning. A vacuum truck equipped
with a suction nozzle is required to clean out debris and collected
sediments.
COST
No cost data are available for this control technique.
STANDARD SYMBOL
Not applicable.
-------
i8"min.
SAND OR 3/4" GRAVEL FILTER
FILTER CLOTH
¦MAXIMUM FROST PENETRATION
3'MIN.
Is" - 3" ROCK
ELEVATION
WITHOUT CATCH BASIN
no scalt
DISCHARGE
OUTLET MAY BE
ELEVATED TO
INCREASE HEAD
GRATE
CURB
FILTER CLOTH
3 MIN
CMP
MAXIMUM FROST PENETRATION
ELEVATION Ij-3«OCK
WITH CATCH BASIN
"no seal*
DRY WELLS
FIGURE QH
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CONTROL TECHNIQUE R
PARKING LOTS AND SERVICE APRONS
DEFINITION
Areas designed for vehicle parking or for access and service work, in
commercial and industrial areas.
PURPOSE
To prevent runoff water from parking lots and service aprons from de-
grading surface waters.
APPLICABILITY
All corporation yards, service station aprons, commercial and industrial
access, service and parking areas, and all residential parking and
driveway facilities greater than 1,000 square feet in total area.
PLANNING CRITERIA
Runoff from paved surface contains significant levels of suspended
materials, nutrients, grease and oils, and other foreign materials
created by vehicular and pedestrian traffic. The initial runoff from a
storm and sustained runoff during snowmelt washes such pollutants off
the surface and conveys them to the point of discharge. In design of
new parking and service facilities and revision of existing ones, in-
filtration of runoff is one technique for preventing the introduction
of these pollutants into surface waters.
Several methods that can be utilized to effectively infiltrate runoff in
an economically feasible manner are described below. Selection of the
appropriate method for a specific site must be based upon an evaluation
of soil type and percolation capacity, land availability, slope of sur-
rounding lands, depth to groundwater, and anticipated runoff water
quality.
Basic design criteria for infiltration facilities, permeable parking,
and pretreatment facilities are presented herein.
Basic Design Criteria
o Parking lots shall be designed to harmonize with existing land
forms and vegetation as much as possible. Natural vegetation
shall be protected.
o Innovative design of parking areas is encouraged. Segregation of
parking areas for small and large cars utilizing landscaping around
-------
parking stalls breaks up the pattern of parking lots and provides
parking for an equivalent number of automobiles with less land
surface coverage.
Infiltration
0 All paved parking lots and service aprons shall provide infiltra-
tion facilities which are capable of storing a 2-year, 6-hour
storm before overflowing into stable drainage facilities.
0 A single infiltration trench is discouraged for parking lots de-
signed for more than eight vehicles. Multiple trenches spaced
throughout the area are preferred.
0 Parking lots can be designed to drain to exterior trenches, in-
terior trenches, or a combination of both. See Figures R-l and
R-2.
0 The necessary capacity of discharge drainage systems can be re-
duced by including storage above the infiltration trenches in
the parking area as shown in Figure R-3.
0 Trenches shall extend a minimum of 3 feet below the line of frost
penetration.
0 Trenches under areas that will receive either pedestrian or
vehicular traffic shall be designed with a grate of adequate
strength to allow snow removal.
0 Wheel stops or segmented curbs are required to keep vehicular
traffic off infiltration trenches not protected by grating. These
devices shall be spaced to allow flow from the parking area into
the infiltration facility.
* The trenches shall be designed so that runoff overflow is routed
to a drainage system. A design to provide surface storage and
increase the capacity of the infiltration system is shown in
Figure R-3. The design storage level is defined by pavement
slope and limit of ponding beyond wheel stops or segmented curb.
« Lateral infiltration trenches under impervious surfaces shall be
designed as shown in Figure R-3.
-------
Pretreatment
Pretreatment using grease and oil traps or other methods may be
required to prevent the entrance of excessive grease and oils,
flotable organic material, and settleable material which may clog
infiltration systems.
o A small grease and oil trap is shown in Figure R-4.
This design is adequate for very small runoff flows.
o Design by a professional engineer is required for larger
applications.
MAINTENANCE
The following statements present the suggested practices for parking
lot and service apron maintenance to achieve the runoff quality criteria
and continued effective use of infiltration and drainage facilities.
If the following practices are not complied with, the only alternative
method to achieve the runoff quality criteria would be to provide treat-
ment facilities to handle all runoff emanating the impervious surfaces
on the site.
o All parking lot and service apron surfaces must be kept clean and
free from substances which will deteriorate the quality of runoff
waters from these surfaces.
o Commercial parking lots, corporation yards, and other impervious
parking surfaces larger than one acre shall be swept or washed
weekly.
° Parking surfaces smaller than one acre shall be washed or swept
once per month.
o These frequencies represent minimum standards. Any time
an exceptional buildup of litter, sediment material, or
debris is present, the surface shall be swept, regardless
of the schedule. Heavy pine needle fall or ice control
activities shall accelerate the sweeping schedule to provide
sweeping as frequently as possible. Sweeping after ice con-
trol shall proceed as expediently as possible following the
drying of the pavement surface.
» Parking lots and service aprons which are subject to use by
heavy vehicles or which for some other reason are subject to
significant discharges of grease or oil shall be washed
during or after sweeping operations.
° Liquid from washing shall be discharged to infiltration systems.
0 Litter and debris shall be periodically cleaned from the surface
of all infiltration trenches.
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Infiltration trenches shall be inspected during major storm and
snowmelt events and periodically throughout the year to ensure
proper operation.
Snow and ice control compounds shall be used only in quantities
necessary for public safety.
All permeable surfaces used for roadways and parking lots shall
be cleaned as necessary to maintain infiltration capacity.
Irrigation shall be supplied if grass is planted in the voids.
Snow plowing shall be conducted carefully to avoid damage to voids
or vegetation.
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STREET
STORM DRAIN SYSTEM
INTERIOR MEDIAN TRENCH
WIDE INTERIOR
INFILTRATION TRENCH
WITH TREES AND
LANDSCAPW6 POTENTIAL.
SLOPE AT 2% TOWARD
TRENCH
TYPICAL SECTIONS IN
FIGURE R-2
CURB
STREET
• STORM ORAIN SYSTEM
LATERAL INFILTRATION
TRENCH AROUND TREE,
SHALLOW TO PROTECT
ROOT SYSTEM
EXTERIOR TRENCH
SLOPE AT 2% TOWARO TRENCH
TYPICAL SECTION IN FIGURE R-2
STORM ORAIN SYSTEM
SLOPE AT 2% TOWARO
TRENCH
INTERIOR TRENCHES
UNDERLAYING PAFKING Lrrr
GRATE OVER INTERIOR COtjj
LATERAL TRENCH SECTION IN
FIGURE R-3
EXAMPLES OF PARKING LOT
INFILTRATION TRENCHES
FIGURE R~i
-------
WHEEL STOPS OR
SECTIONAL CURB
6"MlN. SAP
A. C. PARKING LOT
¦< -Mi. 1
2"-3" FREEBOARD
LINE OF MAXIMUM
FROST PENETRATION
FILTER CLOTH
MIN.
18" MIN.
LATERAL TRENCH
ISOMETRIC
no seal*
PARKINS SURFACE
PARKINS SURFACE
GRATE
2% SLOPF
% SLOPE
FILTER CLOTH
LINE OF MAXIMUM
FROST PENETRATION
MIN.
18" MIN.
INTERIOR PARKING LOT TRENCH
SECTION
no tcale
TYPICAL PARKING LOT
INFILTRATION TRENCHES
FIGURE R-2
-------
DESIGN STORAGE LEVEL
GRATE
FILTER CLOTH
i-3"ROCK
SURFACE STORAGE
SECTION
no seal*
A.C. Pavsmsnr
FiHar Ctofh
Single sized
aggr«gat«
lateral TRENCH
SECTION
NO SCALE
j INFILTRATION TRENCH DETAIL
i FIGURE R-3
-------
48"HEAVY DUTY NON-ROCKING
MANHOLE FRAME AND DOUBLE COVER
(TYP)
R.C. RISER SECTION
MORTAR
WATER-TIGHT WELD
•TRIM FLUSH WITH
INSIDE FACE
1 1 OUTLET TO INFILTRATION
' I TRENCHES ,
C.M.P INLET
¦WATER LEVEL
INLET BAFFLE
GREASE TRAP
MIN.
MORTAR SEAL
!IO"MIN.
ELEVATION
no scale
floatables trap
FIGURE R-4
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CONTROL TECHNIQUE S
DRIPLINE TRENCHES
DEFINITION
Gravel-filled trenches located at the dripline of roofs or other elevated
Impermeable surfaces.
PURPOSE
To intercept and infiltrate runoff from rooftop eaves or other impermeable
surfaces and to prevent erosion of the soil surface from such runoff.
APPLICABILITY
Dripline trenches are required at the dripline of all structures unless
rooftop runoff is conveyed through roof gutters and downspouts to an
acceptable infiltration facility.
PLANNING CRITERIA
The dripline trench design presented herein is applicable to structures
with a roof area not exceeding 3,000 square feet, approximately equivalent
to a single-family residential house. Structures with large roofs, par-
ticularly flat-roofed structures common to shopping centers, shall dis-
charge rooftop runoff to the infiltration and drainage system serving the
adjacent parking facilities, unless dripline trenches are designed with
adequate capacity to handle the rooftop runoff without causing erosion
or the excess runoff is discharged to a stable drainage system. Detailed
design is not usually required unless roof area exceeds 3,000 square feet.
o Trenches shall be placed at the dripline of all structures. Roof-
top runoff collected by a gutter and downspout system shall be
either discharged onto the dripline trench or to a separate in-
filtration facility.
a Dripline trenches shall be shallow gravel-filled trenches located
under the dripline as shown in Figure S-l.
° Dripline trench dimensions shall be double that shown in Figure
S-l within 5 feet on either side of the discharge of rooftop run-
off from a gutter and downspout system.
° If erosion caused by excessive rooftop runoff can occur on adjacent
areas, the trench capacity shall either be increased or excess
runoff shall be discharged to a stable drainage system.
0 Trenches shall be at least 8 inches deep and filled with 3 inches
of fine sand which is covered with a 5-inch layer of 3/4 inch to
1-1/2 inch gravel. Minimum width shall be 18 inches.
-------
Downspout drains shall be similar to the lateral infiltration
trenches shown in Figure R-3.
METHODS AND MATERIALS
As shown on Figure S-l.
MAINTENANCE
Dripline trenches shall be kept clear of significant vegetation growth
which would diminish trench infiltration capacity.
COST
The unit cost for dripline trenches is generally less than $1.00 per
lineal foot..
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Drip Lint —
!2"mm.. 6 min-
Sraul
1 . |
Sand
SECTION
no scale
Orip Lint
Gravel
PLAN
no scale
£
-Oo wr spout
Sutter
Downipaut drain
Discharge from dQurntpaut shall be the Inpims trench
or on infiltration trench as >hown in R-2
DRIPLINE TRENCH
FIGURE S-l
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CONTROL TECHNIQUE T
STORM DRAINS
DEFINITION
Pipes, channels, or other facilities used to collect and/or convey
surface runoff.
PURPOSE
To convey surface runoff in nonerodible conduits or channels.
APPLICABILITY
For conveyance of surface runoff concentrated by natural drainageways,
curb and gutter, or other small runoff collection facilities to a stable
discharge point
PLANNING CRITERIA
General
0
System sizing shall be determined by a registered civil engineer.
O
All natural drainageways originating outside the project area
must enter and leave the project area at the original horizontal
and vertical alignment.
0
The hydrographic characteristics of runoff from a developed site
shall be the same as for undeveloped conditions unless a benefit
from changed characteristics can be demonstrated.
0
Storm drainage facilities (excluding cross-culverts) shall be
parallel with the street centerline wherever possible.
e
Large angular changes in alignment of any drainage facilities
are to be avoided and no change shall exceed 90 degrees.
0
Vegetation shall be established and street surfaces shall be re-
paired on all disturbed areas immediately after drainage system
construction.
Closed
Conduits
0
Minimum diameter of closed conduits shall be 18 inches unless
otherwise approved by the permit-issuing authority.
0
Underground pipe systems are preferred to surface systems in
heavily developed commercial or residential areas.
-------
Direct transitions from a larger upstream pipe diameter to a
smaller downstream diameter shall not be permitted even for slope
changes because of the possibility of clogging, unless a special
transition structure is provided.
° The crowns of all pipe sections shall be matched at any transition
points.
0 Debris control measures such as trach racks shall be incorporated
into drainage system design in those locations where system failure
from clogging could cause damage from flooding or erosion.
0 Inlets and outlets of culverts and storm drains shall be equipped
with wingwalls and aprons as required to prevent erosion and un-
dermining as specified in Control Technique U. A typical outlet
section is shown in Figure U-2.
° Perforated pipe encased in a gravel-filled trench may be used as
soil conditions permit to promote infiltration of surface runoff
and to reduce surface flows.
0 Sediment retention and flow detention basins shall be incorporated
into storm drainage systems wherever possible to reduce peak flows
and keep sediment materials from clogging downstream drainage
facilities.
Channels
° Open channels may be either lined or unlined subject to the follow-
ing permitted velocities:
Permitted Velocity
(ft/sec)
Channel Type Minimum Maximum
Unlined Earthen Ditch 1 2
Riprap Lining 3 10
Grouted Riprap Lining 2 12
Asphalt or Concrete Lined 2 15
Vegetation 2 4
0 Open channels lined with vegetation for erosion control shall have
sideslopes of 3:1 or less and a design flow velocity of 4 feet per
second or less. Determination of hydraulic capacity shall include
evaluation of limitations imposed by mature vegetation.
o Riprap utilized for channel lining shall consist of a well-graded
layer about 1-1/2 times or more as thick as the dimensions of the
largest rock fragments with a bulk specific gravity of not less than
2.5. Minimum size for fines are those that are trapped by a 200-
sieve. Rock fragments shall be large enough to provide surface
protection from erosion during the peak design flows. Riprap lining
L
-------
shall be placed over a filter layer and extended to an elevation of
at least 0.5 feet above the design waterline. The graded filter
layer shall be at least 6 inches thick with a gradation consistent
with the base material and riprap. A typical channel section lined
with riprap is shown in Figure T-l.
° Other methods of channel lining are grouted riprap, sacked concrete,
gabions, concrete, and asphaltic-concrete. These rigid linings
require a firm, compacted, stable foundation and must be carried
below ground slope to prevent undercutting and at least 0.5 feet
above the design waterline. Side slopes shall not exceed 1:1.
° Grade control measures may be required to reduce the gradient of
open channels. Check dams, drop structures, erosion stops, or other
structures shall be located in a reasonably straight channel sec-
tion; constructed of durable materials adapted for use in hydraulic
structures such as concrete, metal, rock, gabions, or treated wood;
and stabilized upstream and downstream at sufficient distances
with riprap or other lining to prevent scour and bank erosion.
0 Channel linings or other structures shall be installed immediately
after channel construction.
MAINTENANCE
Periodic inspection and repair are required to keep all runoff conveyance
systems operable. Regular street vacuum sweeping is recommended to pre-
vent the deposition of large solids in pipes, ditches, and inlet structures,
and to prevent system clogging.
COSTS
Cost estimates are not available.
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0.5 VIN.
DEPTH
GRADED ROCK MATERIAL LAYER
1.5 TIMES THICKNESS CF LARGEST
ROCK FRAGMENTS
3
DESIGN HIGH
WATERLINE
SLOPE ANGLE
21 OR FLATTER
FILTER BLANKET MAY
8E USED IN PLACE OF
FILTER LAYER
FILTER LAYER
(Thickness 0.5* minimum
Sand equivalent not less than 20.)
TYPICAL SECTION
no scale
ROCK LINED CHANNEL
FIGURE T-l
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CONTROL TECHNIQUE U
DISCHARGE APRON AND ARMORED SCOUR HOLE
DEFINITION
A rock-lined apron at the discharge outlet of a drainage facility.
PURPOSE
To reduce the erosive energy and velocity of runoff at discharge outlets
of drainage systems.
APPLICABILITY
To be used on the discharge outlet of all drainage facilities as required
to prevent erosion.
PLANNING CRITERIA
Two energy dissipators in common usage and applicable in Eagle County are
the armored scour hole and rock discharge apron.
Armored Scour Hole
o Design by a professional engineer is usually required.
0 Configuration shall be oval with the long axis parallel to the
drainage discharge.
0 The upper end of the scour hole shall be elipitcal (half of long
axis ¦ 9 feet minimum) and the lower end shall be circular (4 feet
radius minimum) in plan view.
° The hole shall be armored to a minimum thickness of 0.75 times the
diameter of the culvert with rock of which 50 percent is larger
than 0.5 times the diameter of the cantilevered culvert over a
gravel bed.
® Rock shall be placed over a 9-inch layer of filter material as
specified in Control Technique T.
° A typical plan section is shown in Figure U-l.
Rock Discharge Apron
0 Formal design is not normally required.
o Configuration shall be rectangular with minimum dimensions of all
sides equal to four times the inlet pipe diameter.
° 50 percent of the rock shall be larger than 0.5 times the culvert
diameter.
-------
Rock shall be placed over a 6-inch to 9-inch layer of filter
materials as specified in Control Technique T.
A typical section is shown in Figure U-2.
MAINTENANCE
Inspect for damage and repair periodically.
COST
Costs for three sizes of rock discharge aprons are given below:
5' x 6' x 9" Rock Apron + wingwalls $ 350.00
9' x 10' x 15' Rock Apron + wingwalls $ 640.00
24' x 24'x 3' Rock Apron + wingwalls $2,220.00
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ELIPTICAl ! CIRCULAR
CENTER OF
SILTING 3ASIN
PLAN
no scale
6'min.
4' MIN.
CONDUIT
INVERT OF
OUTLET CHANNEL
9'MIN.
MIN
RIPRAP
FILTER CAP
GRADED
FILTER MATERIAL
S" TO 9'
MIN.
9 TO 12
MIN.
MIN.
SECTION ALONG CENTERLINE
no scale
armored scour hole
FIGURE U-l
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SECTION "A-A"
6" to 9" FILTER
MATERIAL
3.5 D MINIMUM
0.5 D
D= DIAMETER
C. M.R
METAL APRON
li
JjJI
W
Q;
50% OF ROCK SHALL BE
LARGER THAN 0.5D
ROCK DISCHARGE APRON
FIGURE U-2
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CONTROL TECHNIQUE V
SHORT TERM PONDING
DEFINITION
The short term detention of rainfall with release at a controlled rate to
storm drains and drainage ways.
PURPOSE
The purpose of short term ponding is to let the same amount of water drain
over a longer period of time than would occur with expeditious drainage.
Thus the quantity and velocity of drainage flows is reduced which in turn
reduces the potential for erosion, localized flooding, and overwehlming
of infiltration facilities.
APPLICABILITY
There are three general areas where short term ponding concepts can be
applied. These are rooftop ponding, plaza and parking lot ponding, and
open space and grassed area ponding. The last two types of short term
ponding are mainly used when high water table conditions make infiltra-
tion trenches, etc. ineffective.
Rooftop Ponding
Flat roofs provide a storage area which does not conflict with people or
traffic and, If releases are properly cofitirolled, maximum roof loads
(usually snow loads) will not be approached. Two techniques have been
used singlely or in combination. The first is to install a detention
ring which fits around the roof drain and extends three inches above the
average roof surface (excluding sumps or depressions around the drain
inlet). Holes 1/4 inch in diameter on two-inch centers are drilled around
the circumference of the ring at the roof surface. Thus retarded flow
through the holes occurs until the depth exceeds three inches, thereafter
overtoping in the manner of a circular weir. The other technique is to
place gravel ridges about four inches high across the roof perpendicular
to the direction of flow. The ridges are constructed of fine grain gravel
with a coarse grain gravel blanket stabilizing the down stream face. The
ridges are placed fifteen to thirty feet apart. With either technique,
shallow wedge shapped ponds three to four inches deep would extend fifteen
feet for a two percent slope. As most roofs are designed for a snow load
equivalent to about six inches of water, allowable roof loads would not
be exceeded. The design runoff rate of one-half inch per hour is the
criteria to be used.
Plaza and Parking Lot Ponding
Plazas, arcades, parking lots, tennis courts, etc. can also be designed
for short term ponding. However, because they accommodate vehicular and
pedistrian traffic, some care is needed in planning ponding areas to
-------
to minimize inconvenience. Therefore, a design runoff flow of one inch
per hour is a more appropriate criteria. The location of outlets and
other shallow ponding areas should be located away from areas of vehicle
and pedestrian traffic. Frequently, the temporary ponding areas can be
integrated with infiltration trenches such as shown in Figure R-3.
Grassed Area Ponding
Grassed areas along the margins of paved areas such as parking lots, side-
walks, and roadways; and as part of planned open space provide frequent
opportunities to incorporate short term ponding in drainage plan. Benches,
swales, and depressed areas should be incorporated into landscaping plans.
Outlets should be designed in accordance with Control Technique T to
control outlet flow velocities.
MAINTENANCE
Generally, no maintenance over and above that normally required for drainage
facilities is required.
COST
Costs are usually inconsequential.
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PART 3
TEMPORARY SLOPE STABILIZATION
AND
REVEGETATION MEASURES
-------
CONTROL TECHNIQUE W
HYDROMULCHING
DEFINITION
The application of plant fiber mulch and tacking agent in a slurry with
water.
PURPOSE
To uniformly and economically apply a temporary stabilization material
(wood fiber, straw, seed free hay) and water to a bare slope or other
bare area. Hydromulch may be combined with hydroseeding as a revegeta-
tion method.
APPLICABILITY
Can be applied to areas which are within approximately 200 feet of a road
or other area which can be reached by truck. Small roadside slopes and
large relatively flat areas are well adapted to this method.
PLANNING CRITERIA
Hydromulching can be combined with seed and fertilizer as a revegetation
method. The mulch will remain up to two years, but loses much of its
effectiveness after the first year. Revegetation is needed to provide
continued stabilization.
Hydromulching shall be used only on physically stable slopes (natural
angle of repose or less).
METHODS AND MATERIALS
0 The hydromulching machine shall be equipped with a gear-driven
pump and a paddle agitator. Agitation by recirculation from
the pump will not be allowed. Agitation shall be sufficient to
produce an homogeneous slurry of tacking agent, mulch, and seed
and fertilizer if used.
° Water shall be applied at a rate of 3,000 gallons per acre.
o Tacking agent shall be applied at 200 gallons of wet ingredients
per acre or 80 pounds of dry ingredients per acre.
o Plant fiber mulch shall be included at a rate of 4,000 pounds per
acre.
° When seeding is combined with hydromulching, fertilizer of the
specified formulation shall be included at the specified rate.
Consult with the soil conservation District or examine control
technique LL to determine seed type.
-------
Specified seed mixtures shall be included. No seed shall
be added to the slurry until immediately prior to beginning
the seeding operation.
Legume seeds shall be pellet innoculated with the appropriate
bacteria. Innoculation rates shall be four times that re-
quired for dry seeding.
The time allowed between placement of seed in the hydromulcher
and the emptying of the hydromulcher tank shall not exceed
thirty minutes.
Plant fiber may be dyed to aid in uniform placement. Dye shall
not stain concrete or painted surfaces nor injure plant or animal
life when applied at the manufacturer's recommended rate.
Application of the slurry shall proceed until a uniform cover is
achieved.
The applicator shall not be directed at one location for a period
of time which will cause applied water to create erosion.
MAINTENANCE
Hydromulched slopes shall be inspected periodically for damage due to wind,
water, or human disturbance. Damaged areas shall be repaired immediately
using hydromulching at the original specifications or straw mulch.
COST
The unit cost for hydromulching is about $1,000.00 per acre.
EFFECTIVENESS
Hydromulching is an effective method of increasing water retention and
thereby reducing erosion for up to six months to one year. Beyond one
year the effectiveness drops off. Initial and short-term effectiveness
for sediment reduction should achieve 70 to 90 percent reduction in sedi-
ment generation from the slope compared to the bare slope. Within two
years, the breakdown of plant fiber will have reduced the effectiveness
to 40 - 60 percent. Beyond that time only 10 to 30 percent effectiveness
can be expected, and the mulch should be replaced. Nutrient reductions
is estimated to be 50 to 70 percent for six months, 20 to 50 percent up
to two years, and O.to 10 percent beyond two years.
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CONTROL TECHNIQUE X
WOOD CHIP APPLICATION
DEFINITION
Temporary mulch and surface protection using chips of wood.
PURPOSE
Slope stabilization for a period of one month to three or four years.
APPLICABILITY
Wood chip applications are useful for temporary dust and erosion control
during construction, and for mulching around vegetative plantings.
PLANNING CRITERIA
Wood chips shall be prepared by processing tree trunks and branches
in a wood chipper, and shall be machine blown or hand spread to
a uniform depth of approximately 3 inches. Chip sizes should be:
width, from 1/2 inch to 1-1/2 inch; length, 1/2 inch to 1-1/2 inch;
thickness, 1/8 inch to 1/2 inch. Chips from kiln dried or air
dried material will not be accepted.
Due to bacterial action during decomposition, nutrient concentra-
tions in the soil may be depressed under a layer of wood chips.
Because of this, applications should not exceed the specified
thickness, which would cause a marked depression in some soil
nutrients for longer periods.
Wood chips are used to mulch revegetation projects. The specified
application of fertilizer shall be increased approximately 25
percent to replenish soil nutrients lost due to breakdown of wood
chips.
MAINTENANCE
Slopes shall be inspected for damage by wind, water, or human disturbance
periodically throughout the year. Damaged areas shall be repaired
immediately according to original specifications.
COST
The unit cost for wood chip application is about $700.00 per acre.
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EFFECTIVENESS
Wood chips deteriorate more slowly than plant and wood fiber and there-
fore retain their effectiveness longer. Sediment generation reductions
of 90 to 95 percent can be expected for a year, 80 to 90 percent up to
two years, and 50 to 60 percent beyond two years. Nutrient reductions
of 60 to 80 percent, 50 to 70 percent, and 30 to 50 percent are estimated
for the same period.
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CONTROL TECHNIQUE Y
FIBERGLASS ROVING
DEFINITION
A matting of continuous strands of glass fibers held together with a
tacking agent.
PURPOSE
Temporary soil' stabilization dust and erosion control for one to three
years.
APPLICABILITY
As a mulch on seeded or unseeded slopes and small drainage channels
PLANNING CRITERIA
Slope stabilization with fiberglass roving aids in mitigating environ-
mental changes near the ground surface and in reducing raindrop impact
and over the slope runoff. It does not supply additional moisture
holding capacity or organic matter as do other mulches.
METHODS AND MATERIALS
0 The materials shall be formed from continuous fibers drawn from
molten glass, coated with a chrome complex sizing compound, col-
lected into strands, and lightly bound together into roving with-
out the use of clay, starch, or other deleterious substances.
Roving shall be wound into cylindrical packages such that the roving
can be fed continuously from the center of the package through
an ejector driven by compressed air, and expanded into a mat of
glass fibers on the soil surface. No petroleum solvents or toxic
substances shall be contained in the material.
° Roving shall be applied within 24 hours after the completion of
normal seeding operations.
° The fiberglass roving mat shall be of uniform density of randomly
laid fibers at approximately 0.25 to 0.35 pounds of fiber per
square yard.
° Asphaltic emulsion tacking agent or its equivalent as shown in
Control Technique EE shall be applied at a rate of 0.25 to 0.35
gallons per square yard to anchor the mat to the ground.
0 To prevent undercutting, the uphill end of the mat shall be placed
in a trench 8 inches deep, which shall be backfilled after roving
is in place.
-------
o The pneumatic ejector shall be capable of applying the roving at
a rate of two pounds per minute.
° An air compressor capable of delivering 40 CFM at 80 to 100 psi
and suitable air hoses are required to drive the ejector.
o An approved distributor for the asphaltic emulsion tacking agent
and all of its associated equipment is required.
MAINTENANCE
If the matting is damaged, it shall be repaired or replaced immediately.
Maintenance inspections shall be made periodically, and the following
procedure shall be used to repair damaged areas:
o Original grade specifications shall be met.
o Any seeding, planting, or fertilizing shall be conducted as per
the original specifications.
o The figerglass mat above the damaged area shall be peeled back to
expose an undamaged area at least 4 feet long upgrade from the
damaged area.
o Fiberglass roving meeting the above specifications shall be applied
at the specified rate to the damaged area and the exposed area
upgrade from the damaged area.
a The upper end of the new mat shall be buried in a trench at least
8 inches deep.
o The old mat shall be replaced over the new mat.
oAsphaltic emulsion shall be applied at the originally specified
rate over the new mat and the overlapped area of the old mat.
<>In extremely unstable areas, staples as specified in Control
Technique BB shall be driven through the overlap area of the old
and new mats. Spacing shall be 18 inches in all directions.
EFFECTIVENESS
Fiberglass roving strands are more durable than wood fiber, but tend to
become broken or damaged as time elapses. Sediment generation reductions
of 90 to 95 percent for one year, 80 to 90 percent for up to two years,
and 60 to 70 percent beyond two years are estimated. Nutrient reduc-
tions for these periods are 60 to 80 percent, 50 to 70 percent, and
40 to 60 percent.
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CONTROL TECHNIQUE Z
STRAW MULCH
DEFINITION
The application of staple straw as a protective cover over bare or
seeded soil.
PURPOSE
To reduce erosion and to provide a mulch for aiding revegetation.
APPLICABILITY
Used on slopes or areas which have been seeded or which may be subject
to wind or water caused erosion. Straw mulch requires matting, crimping,
or other methods to hold it in place.
PLANNING CRITERIA
° Straw mulch provides organic matter as it breaks down and is
incorporated into the soil. If applications are too heavy,
however, reduction of soil nutrient levels, especially nitrogen,
may occur during the period of decomposition. Therefore, appli-
cation rates of both the straw mulch and the fertilizer specified
shall be strictly adhered to.
° Straw mulch forms a loose layer when applied over a loose soil
surface. To protect the mulch from wind drifting and water damage,
it must be stabilized by covering it with a netting such as jute,
by punching it into the soil with a spade or roller, or by spray-
ing it with a tacking agent.
0 Straw mulch shall cover the entire seeded area or exposed slope.
The mulch shall extend into existing vegetation or stabilized
areas on all sides to prevent wind or water damage which may start
at the edges of the mat.
METHODS AND MATERIALS
0 On small slopes, straw mulch shall be applied by hand broadcasting
to a uniform depth of 2 to 3 inches.
8 On larger slopes, straw shall be blown onto the slope to achieve
a uniform cover of 2 to 3 inches.
° The straw fibers shall be applied to form a uniform mat of loose
straw through which approximately 20 to 40 percent of the original
-------
ground surface can be seen. No large clumps of unscattered straw
exist after application.
Application rate shall be 2 tons of straw per acre, which should
provide a 2 to 3 inch covering of straw on the ground surface.
The maximum depth shall be 3 inches except on soils subject to
frost heaving where 4 inches shall be applied.
Straw shall be clean rice, barley, or wheat straw. Fibers shall
not be chopped or ground to reduce the fiber length.
Stabilization of the mulch mat should be by one of the following
methods:
0 Hand Punching - Used on small sites, sites with much rock
and stone on the surface, sites with slopes which are steeper
than 3:1, or sites which have been wattled. Care must be
taken not to damage wattling or planted vegetation. A spade
or shovel shall be used to punch the straw into the slope
until all areas have straw standing perpendicularly to the
slope and embedded at least 4 inches into the slope. The
bunches of straw should resemble the tufts of a toothbrush.
o Roller Punching - Used on large, gently sloping sites without
significant outcroppings of rock and stone. Not to be used
on sites which have been wattled unless adequate space
between lines of wattling is available, or on vegetatively
planted sites. A roller equipped with straight studs not
less than 6 inches long, from 4 to 6 inches wide, and approxi-
mately 7/8-inch thick, will best accomplish the desired effect.
Studs should stand approximately 8 inches apart and should be
staggered. All corners should be rounded to prevent withdraw-
ing the straw from the soil. Rollers should not be used to
punch straw on slopes which have been wattled or vegetatively
planted. Vegetative planting may be conducted following
roller punching.
° Crimper Punching - Specially designed straw crimping rollers
are available for use wherever roller punching can be used.
These crimpers consist of serrated disk blades set 4 to 8
inches apart which force straw mulch into the soil. Crimping
should be done in two directions with the final pass conducted
across the slope rather than up and down it.
0 Tacking Agent - To be used on any type of site, but best used
only on very stony or rocky soils or small, steep slopes. Two
hundred gallons per acre of asphaltic tacking agent or its
equivalent should be applied over the straw mulch. Agents
which are neutral or nearly neutral in color and of demonstrated
effectiveness in the soils and climate of the Upper Eagle
Valley are acceptable.
o Matting - To be used on large, steep areas which cannot be
punched with a roller. Jute or wood excelsior on plastic
matting shall be applied over unpunched straw according to
Control Techniques BB, CC, or FF.
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COST
The unit cost for straw mulch is $550 to $600 per acre for small sites or
for hand spreading, and $200 to $400 per acre for large sites.
EFFECTIVENESS
Straw mulches react similarly to hydromulches, as they break down fairly
rapidly. Sediment generation reduction from straw mulch without vegeta-
tion is from 90 to 95 percent for a few months, but drops off to 70 to
90 percent in six months, and further to 40 to 60 percent in two years,
and 10 to 30 percent after that. Nutrient reductions are estimated at
60 to 80 percent for a few months, 50 to 70 percent in six.months, 20
to 50 percent up to two years, and 0 to 10 percent beyond two years.
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CONTROL TECHNIQUES AA
CRUSHED STONE AND GRAVEL MULCHES
DEFINITION
The application of gravel or crushed stone as a mulch.
PURPOSE
To stabilize soils during construction activities and for other temporary
periods.
APPLICABILITY
On construction sites, low-use dirt roads, driveways, and other areas of
light vehicular activity.
PLANNING CRITERIA
Gravel or crushed stone of approximately 3/4 inch to 1-1/2 inch
diameter may be used interchangeably. At least 50 percent of the
material should be larger than 3/4 inch in diameter. Apply material
in a uniform covering.
Application rates shall be at least 100 tons per acre, with a
minimum acceptable surface coverage of 90 percent. If the material
used does not supply 90 percent coverage at 100 tons per acre, the
application rate shall be increased.
After the gravel or stone is applied, construction or other traffic
may move over it. Areas which become compacted or depressed should
be remulched to the same level as the remaining area to prevent
flows from the site from becoming channelized into these depressions.
Upon completion of activities on the site, the gravel or stone
mulch may be left in place during revegetation operations.
When used for driveways or dirt roads, a filter blanket shall be
placed under the gravel.
COST
The unit cost for this method is approximately $650.00 per acre.
EFFECTIVENESS
Crushed stone and gravel mulches retain their effectiveness indefinitely
if properly applied and protected from compacting traffic. Sediment re-
duction is estimated at 70 to 90 percent, and nutrient reduction at 50 to
70 percent.
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CONTROL TECHNIQUE BB
JUTE MATTING
DEFINITION
Mulch nets made of jute.
PURPOSE
Slope stabilization, erosion control, and protection of mulches from
wind or water damage.
APPLICABILITY
Jute matting can be applied over straw, wood fiber, or manure mulches
when wind velocities or runoff quantities and velocities indicate damage
to mulches would occur without a protective net. It may be applied
alone as an alternative to straw or wood fiber mulches on flat sites
for dust control and seed germination enhancement, but shall not be
applied alone where runoff quantities are significant.
PLANNING CRITERIA
Jute netting is a heavy fiber net which is generally purchased in rolls
and is stapled to slopes to provide a uniform covering. This covering
protects mulches, provides additional water-holding capacity, and aids
in moderating environmental fluctuations near the ground surface, as does
a mulch. Greater integrity of a mulched area results from the use of
this covering than from any other single method, such as punched straw.
The soil must be reasonably smooth. Gullies and rills must be filled
and compacted. Rocks or other obstructions which rise above the level
of the soil and mulch must be removed. Slope stabilization shall be
used where necessary to achieve the slope design criteria.
METHODS AND MATERIALS
° Application shall be as specified below. Care in installation is
required due to the unstable nature of the region's soils when dis-
turbed on steep slopes.
® The details of installation are shown in Figure BB-1.
0 Jute mat shall be cloth of a uniform plain weave of undyed and un-
bleached single jute yarn, 48 inches in width plus or minus 1
inch and weighing an average 1.2 pounds per linear yard of cloth
with a tolerance of plus or minus 5 percent, with approximately 78
warp ends per width of cloth and 41 weft ends per linear yard of
cloth. The yarn shall be of a loosely twisted construction having
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ail average twist of not less than 1.6 turns per inch and shall not
vary in thickness by more than 1/2 of its normal diameter.
0 Individual rolls should be applied up and down the slope, never
along the contour.
0 Sides of rolls shall overlap at least 4 inches, and rolls shall
have at least a 3-foot overlap when an uphill roll joins to a
downhill roll. The uphill roll shall overlie the downhill roll.
0 Staples shall be made of wire, 0.091 inches in diameter or greater,
"U" shaped with legs at least 6 inches in length and a 1—inch crown.
Longer staples are required in loose or sandy soils.
0 Staples .shall be driven perpendicularly into the slope face, and
shall be spaced approximately 5 feet apart down the sides and
center of the roll. Spacing between staples at the upper end of
a roll or at the end overlap of two rolls shall not exceed 1 foot.
0 Matting shall be continued beyond the edge of the mulched or seeded
area at least 1 foot at the sides and 3 feet at the top and bottom
of the area. If existing vegetation or structures mark the bound-
aries of the area, the matting shall be continued into the stable
vegetated area or to the edge of the structure.
° The upper end of the matting at the top of the area shall be buried
in a trench at least 8 inches deep.
o The matting shall make uniform contact with the slope face under-
neath. No "bridging" of rills or gullies is allowed.
COST
The unit cost for jute matting is $3,500 to $5,000 per acre.
EFFECTIVENESS
Jute netting acts similarly to straw mulch or hydromulch. Sediment
reduction for up to six months is 70 to 90 percent, with 40 to 60 per-
cent expected for up to two years, and 10 to 30 percent beyond two
years. Nutrient reductions are estimated at 50 to 70 percent for six
months, 20 to 50 percent for up to two years, and 0 to 10 percent beyond
two years.
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BURY UPPER END
OF MATTING
I SPACING
OF STAPLES
8 MIN
LIMITS OF
MULCHED AREA
EXTEND MATTING OVER
SIDES ANO TOP OF
MULCHED AREA
I SPACING
OF STAPLES
3 MIN.
OVERLAP
4 MIN. OVERLAP
/
5' SPACING OF STAPLES
ALONG EACH EDGE AND
CENTER OF MATTING
JUTE MATTING
FIGURE BB-I
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CONTROL TECHNIQUE CC
WOOD EXCELSIOR MATTING
DEFINITION
A mat made of wood excelsior fiber bonded to a paper or plastic reinforc-
ing net.
PURPOSE
Temporary soil stabilization, erosion control, and mulching on construc-
tion or revegetation sites.
APPLICABILITY
This method can be utilized in the following circumstances:
0 Construction sites becoming temporarily inactive (inactive period
greater than two weeks and less than one year).
° Graded areas receiving permanent revegetation treatment by seeding.
» Bare areas receiving permanent revegetation treatment by seeding
° As an alternative to jute netting.
PLANNING CRITERIA
Wood excelsior matting is a heavy wood fiber net which is generally pur-
chased in rolls and is stapled to slopes to provide a uniform covering.
This covering protects mulches, provides additional water-holding capac-
ity, and aids in moderating environmental fluctuations near the ground
surface, as does a mulch. Greater integrity of a mulched area results
from the use of a net or mat covering than from any other single method,
such as punched straw.
The soil must be reasonably smooth. Gullies and rills must be filled
and compacted. Rocks or other obstructions which rise above the level
of the soil or mulch must be removed.
Due to the difficulty of placing wood excelsior matting and its less
predictable results in controlling erosion, jute matting is preferred.
METHODS AND MATERIALS
° Excelsior blankets shall consist of machine-produced mats of curled
wood excelsior of 80 percent of which have an 8-inch or longer
fiber length. It shall be of consistent thickness with the fiber
evenly distributed over the entire area of the blanket. The top
side of each blanket shall be covered with a 3-inch by 1-inch weave
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of twisted Kraft paper or biodegradable plastic mesh that has a
high wet strength. Blankets shall be fire and smolder resistant
and contain no chemical additives. Blankets shall be in 3-foot
by 150-foot rolls or in 4-foot by 180-foot rolls.
If the wood excelsior mat is to be applied without other mulches,
the minimum thickness of mat shall be 1-1/2 inches.
If the wood excelsior mat is to be applied over other mulches, the
minimum thickness shall be 1/2 inch.
After site preparation and seeding (if any), the rolls of wood
excelsior matting shall be rolled onto the surface from the top of
the slope to the bottom of the slope, never along the contour.
The upper end of each blanket shall be buried in a trench at least
8 inches deep, and the trench shall be backfilled and tamped.
(Refer to Figure BB-1 which relates to jute mat placement.)
Staples shall be applied at 2 feet on center along the sides of
the blanket and 4 feet on center along the center of the blanket.
Blankets placed side-to-side shall be snuggly butted together to
prevent rilling and gullying along the joint.
Blankets placed end-to-end shall be overlapped. The top of the
lower blanket shall be placed in an 8-inch deep trench which shall
then be backfilled and tamped. The lower end of the upper blanket
shall be overlapped onto the lower blanket, and staples shall be
placed through both blankets. (Refer to Figure BB-1 which related
to jute mat placement.)
Staples shall be of heavy guage wire, 0.091 inches in diameter or
greater, which have been bent into a "U" shape, with legs at least
8 inches long, and a 1-inch crown. Longer staples are required in
loose or sandy soil.
COST
The unit cost for wood excelsior matting is about $2,400 per acre.
EFFECTIVENESS
Due to the difficulty of proper application, wood excelsior matting has a
more variable effectiveness than straw, jute, or hydromulch. Properly
applied, it can be as effective. Sediment reduction should range from
50 to 90 percent, 20 to 60 percent, and 0 to 30 percent in six months,
two years, and beyond two years, respectively. Nutrient reductions for
the same time periods are estimated to be 30 to 70 percent, 10 to 50
percent, and 0 to 10 percent.
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CONTROL TECHNIQUE DD
INSTALLING MATTING IN DRAINAGE CHANNELS
DEFINITION
The use of jute, fiberglass roving, or filter cloth as a soil stabilizing
agent in erodible drainage facilities.
PURPOSE
To stabilize open drainage channels.
APPLICABILITY
This method has limited applicability in very small drainage channels
with flow velocities less than 2 feet per second and where erosion prob-
lems are not anticipated. Matting shall be used with seeding for perma-
nent grassed waterways.
PLANNING CRITERIA
0 Matting shall be used only for first order streams which do not
normally contain water other than during snowmelt or rainstorm
runoff. Flow velocities shall not exceed 2 feet per second.
o The drainageway must have a configuration which is amenable to this
this type of control. The optimum configuration is a low gradient,
shallow, "U" shaped swale without physical instability. The
material should be well compacted.
METHODS AND MATERIALS (See Figure DD-1)
o Site Preparation - Shape and grade the waterway, channel, or area
to be protected as required by job plans and specifications. Re-
move rocks, clods over 1-1/2 inches in diameter, sticks, and other
material that will prevent contact of the matting with the soil
surface. Lime, fertilize mulch, and seed in accordance with the
applicable seeding methods.
0 Placing the Matting - Apply the matting from the top of the channel
or slope and continue downgrade.
« When jute is used, one edge of the strip of netting or matting
shall coincide with the channel center. Lay a second strip
parallel to the first on the other side of the channel and
allow at least a 4-inch overlap. If one roll of matting does
not extend the length of the channel, continue downhill with
additional rolls.
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0 Fiberglass roving shall be laid continuously down the channel
in a manner similar to that used on slopes.
Securing the Matting - Bury the top end of the matting in a trench
8 inches deep. Backfill and compact the trench. Reinforce with
a row of staples driven through the material about 4 inches down-
hill from the trench. These staples should be placed on 1-foot
centers.
° For jute, staple the overlap in the channel center with
staples spaced 2 feet apart. The outside edges shall be
stapled similarly after the center has been stapled. Closer
stapling along the sides is required where water may flow
into the channel from the side (See Figure DD-1).
Overlapping the Matting - Where one roll of matting ends and another
roll begins, the end of the upper roll overlaps the trench where
the upper end of the lower roll is buried. Make the overlap at
least 3 feet and staple securely through both layers.
0 Roving shall be tacked down with a tacking agent.
Erosion Stops - May be installed at any point. Jute matting may
be folded for burying in slit trenches and secured as were the
upper ends. This checks water flow and erosion that may begin
under the matting. It also gives improved tie-down. The procedure
is recommended on the steeper slopes, sandy soil, and slopes sub-
ject to seepage. See detail in Figure DD-1. Spacings shall be
determined from the relation:
Slope Ratio (12.5)
Rainfall Intensity
S » Spacing in feet
Slope Ratio ¦ 4:1, 3:1, 2:1, etc.
Rainfall Intensity - in/hr
Tributary Inflows - The outlet should be protected with matting
used in the same manner as in the main channel. The matting for
the outlet is applied first and the matting in the main channel
overlaps the outlet strip as shown in Figure DD-1.
Matting Soil Contact - To achieve complete contact of the netting
with the soil surface, the channel lining shall be rolled with a
heavy roller after laying, stapling, and seeding are complete.
Complete contact is vital to keep water flow over—not under—
the matting.
Inspection - After job completion, make sure the matting is in
contact with the soil at all places and that critical areas are
securely stapled.
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MAINTENANCE
Inspect following each major storm or snowmelt event and repair as
necessary.
If the grass has not become established, jute mat shall be re-
placed, taking care not to disturb any areas of established grass
If vegetation has not been established, fiberglass lining shall
be replaced when it deteriorates to an extent that its soil
stabilizing capacity is reduced.
COST
The unit cost of installing jute matting in drainageways is about $3,400
per acre.
EFFECTIVENESS
Values for matting installed in drainageways are variable due to several
design and installation variables. Estimated sediment reductions of
50 to 90 percent can be expected for up to six months with jute. This
effect declines to 20 to 60 percent in two years, and 10 to 30 percent
after more than two years. Nutrient reductions of 30 to 70 percent,
10 to 50 percent, and 0 to 10 percent are estimated for the same periods
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Staples or 2' o.c.
3' rnin.
Staples at 1' o.c.
_ Flow
^4—
•Bury 8
EROSION STOP
3' overlap
see detail
Secon^Qfy
side fjow
Staples at 4' o.c.
Erosion stop
See detail
¦2 rnin
rows of staples
overlap
L
4 min. overlap
JUTE CHANNEL LINING
FIGURE DO-l
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CONTROL TECHNIQUE EE
CHEMICALS AND TACKIFIERS
DEFINITION
Plastics, organic seeding additives, asphaltic tacking agents, and other
similar products used in slope stabilization.
PURPOSE
To 'tack' erosion control fibers to slopes and fc?r dust and erosion con-
trol.
APPLICABILITY
These products shall be used to aid the stabilization of mulches where
matting is not used and for temporary dust and erosion control on
inactive construction sites.
PLANNING CRITERIA
No chemicals or tackifiers shall be used if an alternative method has
been demonstrated to be effective for soil stabilization in the same
conditions. The appropriate applications of these compounds are limited
to use upon steep and rocky slopes where neither mechanical methods nor
mulches and protective neeting may be effectively applied and to con-
struction sites for temporary dust and erosion control. Careful selection
of brands of products is extremely important as some have demonstrated
no beneficial effect. The proposed application rate of all products
shall be of demonstrated effectiveness.
METHODS AND MATERIALS
All products shall be applied according to the manufacturer's recommended
procedure. When portions of a product must be mixed, thorough mixing
shall be accomplished in an appropriate container, such as a hydroseeder
mixing tank.
9 Fibers - When applied for temporary purposes, these agents shall
be mixed with 150 pounds of wood fiber per acre:
0 All plastic, resin, or other chemical soil stabilizing agents,
additives, and "binders" or "tackifiers" which are to be used
in a permanent application with seed and mulch shall be
applied over wood fiber or straw.
° Wood fiber may be applied by hydromulching or by blowing.
Straw may be blown or hand spread. The tackifier shall be
sprayed onto the surface after the wood fiber or straw is in
place.
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Organic Seeding Additives
Acceptable products shall be of one of the following com-
positions :
A free-flowing powder produced from seaweed extracts,
consisting of an alginase and a jelling agent. Proper
mixing of these two parts is essential.
A natural gum derived from seeds, which becomes
mucilagenous upon wetting
Application shall be at a rate which has been demonstrated
to be effective in the Upper Eagle Valley. Manufacturers
representatives and erosion control specialists shall be
consulted. Seed gums shall be applied according to manu-
facturer's specified rates, and seaweed extract powders shall
be applied at 90 pounds of chemical per acre.
Plastics
Plastics shall be used to temporarily stabilize soils exposed
by construction and for specific sites which have extreme
cycles of wetting and drying.
Acceptable products shall be those of polyvinyl acetate or
styrene butadiene ("Soil Bond," "Enviro," or equivalent).
Application rates shall be 1,000 pounds of solids per acre
when applied without fiber. When applied with fiber, the
application rate shall be 160 pounds of solids per acre and
1,000 pounds of fiber per acre.
When applied with seed, plastics shall be applied in a
second operation over the seed.
When applied with plastics, seeding rates shall be doubled.
COST
The unit cost of applying chemicals and tackifiers is about $850.00
per acre.
EFFECTIVENESS
Soil stabilizing chemicals and tackifiers can achieve 70 to 90 percent
reduction of sediment generation for the first six months. Deterioration
of these agents reduces these figures to 40 - 60 percent in two years,
and 10 to 30 percent beyond two years. Nutrient reduction is estimated
to be 50 to 70 percent, 20 to 50 percent, and 0 to 10 percent for the
same periods.
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CONTROL TECHNIQUE FF
NATIVE ROCK RETAINING MALL
DEFINITION
A low gravity wall constructed of rock materials native to the Upper
Eagle Valley.
PURPOSE
To provide an aesthetically attractive method for physically stabilizing
a slope.
APPLICABILITY
The design described below should be used for low gravity walls up to
about 5 feet in vertical height on slopes which are steeper than 2:1 and
cannot be regraded to achieve this gradient. Design of retaining walls
of any substantial height should be completed by a registered civil
engineer.
METHODS AND MATERIALS
0 Rocks originating from Evaporite, gypsum, shale or similarly
erodible formations shall not be used.
0 Remove all large rocks from the eroding sloping face and stockpile
on site.
° Excavate a footing trench along the toe of the slope (Figure FF-1)
« Place the largest rocks in the footing trench with their longi-
tudinal axis normal to the embankment face.
" Arrange subsequent rock layers so that each rock above the founda-
tion course has a three-point bearing on the underlying rocks.
0 The slope of the wall shall be between 1/2:1 and vertical, de-
pending upon the height of the wall, the height of the slope, or
the width of the right-of-way, or other limitations on space.
0 Obtain fill material from the slope and place behind the rock wall
Slope above the wall shall be maintained at 2:1 or less with a
slope bench at the toe as specified in Control Technique JJ.
Backfill the footing trench with excavated material.
0 If a roadway is located at the toe of the wall, pave the roadway
up to the base of the rock wall and provide roadway curb for water
transport (Figure FF-1) If a roadway is not located at the toe of
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the retaining wall, slope the backfilled material away from the
wall at 2 percent and stabilize it.
0 Revegetate the stabilized slope immediately with a method applicable
to the particular site.
° The determination of final wall height, requirements for drainage,
and acceptability of rock material must be made by on-site inspec-
tion.
MAINTENANCE
Inspect periodically for damage caused by subsurface drainage or material
sloughing. Repair as needed.
COST
The unit cost of native rock retaining walls is about $45.00 per lineal
foot assuming a four-foot high retaining wall.
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| Mm width : 1/3 wal I hsiqht
Wall hei
Average surface
slope of rock.
A pproximate
line of soil
infiltration
5 —
: | mm.4/
footing increase
L.2:l slope
or flatter
Vls/fa. :
2 min.
V^.
p>Native stone
'A*'/*? ///?.
smmvwi
Extend paving to base
of rock wall
3' '
l~ 1
Alternative paving design
¦^The wall may vary from vertical toon angle of 1/2: I NATIVE ROCK RETAINING WALL
FIGURE FF-I
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CONTROL TECHNIQUE GG
GABIONS
DEFINITION
Large, single- or multi-celled rectangular wire mesh boxes that are filled
with rock and wired together to form a protective structure.
PURPOSE
Permanent slope or drainage stabilization and erosion control.
APPLICABILITY
Gabions can be used to mechanically stabilize oversteepened slopes as
retaining walls, or for revetments, weirs, channel linings, culvert
headwalls, and culvert outlet aprons. They are particularly useful where
seepage is anticipated.
PLANNING CRITERIA
Gabions are rock-filled baskets which when wired together form flexible,
permeable, and monolithic building blocks that can be used for construc-
tion of erosion control structures. The wire baskets must be assembled
and wired in position. The rock filling holds the gabions in place by
gravity, but tie-backs may be used if conditions warrant additional
structural strength.
METHODS AND MATERIALS
° Construction plans and specifications shall be prepared by profes-
sionals familiar with the use of gabions.
° Site preparation requires rough grading of the site.
° Empty gabions are placed into position, wired together, and filled
with rock.
o Erosion and sediment control construction design should ensure
that foundations are properly prepared to receive gabions, that
the gabion structure is securely "keyed" into the foundation and
abutment surfaces, and that rock used is durable and adequately
sized to be retained in the baskets, approximately 4 to 8 inches
in diameter. Rocks from Evaporite, gypsum, shale or similar
formations shall not be used.
° Typical sketches of two low gabion retaining walls are presented
in Figure GG-1. Other possible uses for gabions include slope
revetment as shown in Figure GG—2, and channel stabilization and
drop structures.
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MAINTENANCE
Periodic inspection is necessary for signs of undercutting or other
instability. Damaged areas shall be repaired immediately.
COST
The unit costs for gabion retaining walls is about $18.00 per lineal
foot for a three-foot high wall. This cost increases by the following
factor:
If Wall Height is; Cost is $18 Times:
3 ft 1.0
6 ft 2.5
9 ft 4.5
12 ft 7.0
15 ft 10.0
18 ft 13.5
21 ft 17.5
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A 2 I max.
6 mm.
ISOMETRIC
no scale
2%
-ii
6 mm.
GABION RETAINING WALLS
FIGURE GG—t
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3.0"
///
^ \\\
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PART 4
PERMANENT SLOPE STABILIZATION
AND
REVEGETATION MEASURES
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CONTROL TECHNIQUE HH
WATTLING
DEFINITION
Bundles of cuttings from growing willows, alders, or similar plants
used for slope stabilization.
PURPOSE
Stabilization of slopes and revegetation by producing favorable seed
germination sites, reducing slope lengths for uninterrupted surface
runoff, increasing water retention, and producing additional organic
matter.
APPLICABILITY
Wattling is best applied to slopes which are no steeper than two hori-
zontal to one vertical (2:1). Slope lengths which produce long, unin-
terrupted paths for surface runoff can be effectively reduced with rows
of wattling. Wattling cannot be used as a substitute for retaining walls
or similar devices to stabilize oversteepened slopes. Wattling is best
applied to moist sites, but can be used on fairly dry sites.
PLANNING CRITERIA
Wattling can aid in achieving surface stability on a slope which is near
its angle of repose but which continues to erode due to surface runoff,
frost heaving, needle ice, or other soil movement. Wattling bundles can
vegetatively root and grow and continue to stabilize slope surfaces as a
revegetation planting. Rooting and growth occur when adequate water is
available both at the time of placement and during the first few growing
seasons.
The maximum spacing (S) between lines of wattling bundles on a slope
face can be calculated using the equation in Control Technique DD.
METHODS AND MATERIALS
Preparation of Bundles
0 Wattling bundles shall be prepared from living branches of shrubby
material, preferably of species which will root, such as Salix
spp. (Willow) and Alnua ssp. (Alder).
0 Wattling bundles may vary in length depending on materials available,
but shall be at least 5 feet long. Bundles shall taper at the ends
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and shall be at least 5 feet long. Bundles shall taper at the
ends and shall be 1 to 1-1/2 feet (maximum 2 feet) longer than
the average length of the Individual branches to achieve this
taper. Butts of branches shall be no more than 1-1/2 inches in
diameter.
o Alternate the direction of branches in each bundle so that approxi-
mately one-half of the butt ends lie at each end of the bundle.
o When compressed and tied, each bundle shall be 6 to 10 inches in
diameter.
° Bundles shall be tied on not more than 16-inch centers with two
wraps of binder twine or heavier tying material using a nonslip
knot.
° Prepare bundles not more than two days prior to placement, unless
they are kept covered and moist. In that case, they can be pre-
pared up to seven days prior to placement.
° Willow wattling should be cut in the spring prior to the appearance
of any substantial foliage or late in the fall once the branches
have returned to a dormant state. Cutting and planting of willows
when they are foliated during the summer will lead a rapid drying
of the branches and greatly reduce the success of willow growth.
If wattling must be cut and planted in the summer months, strip all
leaves from the branches to reduce moisture loss.
Installation
° Existing qullies and rills shall be filled and compacted prior to
installation of wattling. Disturbance of the slope face and any
existing vegetation shall be minimized.
o Grade for wattling trenches shall be staked with an Abney level or
similar device and shall follow slope contours.
o Determine trench spacing on large slopes using the formula for de-
termining the spacing.
° Bundles shall be placed in contour trenches dug 3 to 5 inches in
depth and 6 to 10 inches across.
o Place stakes on 16-inch centers on the downhill lip of the trench.
o Stakes shall be live wattling material of greater than 1 inch
diameter or 2 inch by 4 inch lumber or construction stakes.
Live stakes are preferred. Lumber stakes may be used in com-
pacted soils which prohibit effective use of live stakes.
Stakes shall be 24 inches to 36 inches long. Steel reinforc-
ing bar can be substituted only as specified below.
o Bundles shall be placed in the trenches so that the ends of two
bundles shall overlap at least 1 foot. The overlap should be as
long as necessary to permit staking as specified.
« Bundles of wattling shall be staked through the center on approxi-
mately 30-inch centers. Place extra stakes on the downhill lip of
the trench and trhough the bundles at each overlap of two bundles.
-------
Stakes can also be placed between rows of wattling to aid in re-
vegetation.
0 All stakes shall be driven in to a firm hold, a minimum of 18
inches deep. Where soils are soft, longer stakes shall be used.
Where soils are so compacted that 24-inch wooden stakes cannot be
driven in 18 inches, 24-inch sections of 3/8-inch to 1/2-inch
diameter steel reinforcing bars may be used for staking.
0 Work shall proceed from the bottom of the slope to the top. Each
row of wattling shall be covered with soil and packed firmly on
the uphill side by tamping or walking on the wattling as the work
progresses up the hill. The downhill lip of the wattling may be
left exposed when staking and covering are completed.
° Additional wattling shall be placed as necessary for stability in
seeps or other wet areas.
0 A slope bottom bench shall be placed below the slope as specified
in Control Technique II.
0 The slope shall be revegetated according to specified procedures.
Performance of Work
The following procedure is recommended for work crew organization when
placing wattling. Refer to Figure HH-1.
0 Have one crew gather wattling material and prepare it in bundles
prior to moving to the site.
0 For small jobs, all of the wattling can be prepared prior to com-
mencing work on the job site.
° For large jobs, prepare approximately half of the wattling bundles
prior to commencing work on the job site. Keep a crew of three
to four persons making wattling bundles and transporting them to
the job site while work proceeds.
0 When work on the site begins, stake out the first trench lines
with stakes on 16-inch centers using an Abney level or similar
device.
0 Dig the trench to a specified depth and width just above the line
of stakes. Large rocks which are in the path of a trench should
not be removed, but the trench should end at the rock and resume
on the other side.
0 Lay wattling bundles in the trench and stake them down, placing
additional stakes through overlaps between bundles and stakes on
the downhill side of all overlaps of bundles.
° When bundles are in place, stake out the next trench line while
standing on the first line of wattling.
0 The material excavated from the second trench should be cast on
top of the first line of wattling. This material may be compacted
by walking upon it while placing the bundles in the second trench
and staking them. The greater the amount of traffic that the
-------
placed wattling receives, the greater will be the number of rooting
locations in the bundles.
° Try to avoid traffic on the rest of the slope as much as possible.
Walk on the wattling lines.
° Work up the slope using the last placed line of wattling as a base
from which to apply the next line.
MAINTENANCE
Wattling should be inspected after each storm, and in the spring during
heavy snowmelt, and repairs made as necessary until vegetation becomes
established.
COST
The unit cost for wattling is about $3,000 per acre.
-------
LIVE
STAKE 16" 0 C.
.18 Mm
STEP I. STAKE ON STEP 2. TRENCH ABOVE STEP 3 PLACE BUM5LES STEP 4 AOD STAKES STEP 5. COVER
CONTOUR STAKE, 1/2 DIA. OF IN TRENCH THROUGH AND WATTLING WITH
BUNOLES. CAST SOIL BELOW BUNDLES SOIL, TAMP FIRMLY
FROM TRENCH DOWNHILL
NOTE I. WORK FROM BOTT TO TOP OF CUT OR FILL
Z. WALK ON BUNOLES TO COMPACT OVERLAY SOIL
3. STAKES SHOULD 8E LIVE WATTLING MATERIAL
4 SPACING OF ROWS SHALL BE DETERMINED BY
BMP IV- B
PREPARE WATTLING' CI6AR-SHAPED BUNOLES OF LIVE BRUSH WITH BUTTS
ALTERNATING, 8-10" DIA., TIED I2-IS"0.C. SPECIES WHICH ROOT ARE
PREFERRED.
LEVEL LNES OF
WATTLING^.
AOOITIONAL
WATTLING IN
SEEP AREA
LIVE STAKES PLACED
BETWEEN WATTLING
FOR REVEGETATION
ROADWAY
SURFACE
SLOPE BOTTOM BENCH
BMP VI-E
WATTLING INSTALLATION
figure hh-i
-------
CONTROL TECHNIQUE II
SLOPE BOTTOM BENCH
DEFINITION
A gently sloping surface at the base of a steeper slope.
PURPOSE
To retain material eroded from the slope.
APPLICABILITY
Used for erosion control on existing small oversteepened slopes (20 feet
or less) that cannot be regraded because of easement or inaccessability
to equipment and on all newly constructed or regraded cut slopes.
METHODS AND MATERIALS
Install roadside curb and gutter, retaining wall, or other mech-
anical stabilization facilities where none exists along the slope
toe.
Pull material from the slope with a backhoe or similar equipment
and backfill behind the curb creating a bench approximately 3 feet
wide. Compact to a finished grade of 2 percent sloping down from
the slope toe to the top of the curb or retaining wall. Regrade
existing slope face as required (Figures II-l and FF-1).
For benches constructed along roadways with a grade steeper than
5 percent, the steepness of the bench slope must be increased above
2 percent to prevent lateral water movement behind the curb parallel
to the street.
Revegetate the entire slope face, including the bench, with ap-
propriate method.
MAINTENANCE
Allow material sloughing off the slope to gradually build up. Revegetate
bench as required to maintain vigorous growth. Do not remove material
deposited on the bench unless the quantity present could cause sloughing
into the adjacent curb drainage.
COST
The unit cost for a slope bottom bench is $5.00 to $6.00 per lineal foot.
-------
2:1 slope or flatter
> a -• l
Curb & road surface
Round slope toe
SECTION
no scale
SLOPE BOTTOM BENCH
FIGURE II-I
-------
CONTROL TECHNIQUE JJ
SLOPE SERRATION
DEFINITION
The construction of approximately 10-inch square, horizontal steps on
the entire face of a cut slope.
PURPOSE
To provide stabilized benches on which vegetation can become established.
APPLICABILITY
Serration is limited to slopes in medium to highly cohesive soils or in
soft rock which can be excavated without ripping. Slope angle must be
gentle to permit access to heavy equipment (2:1 or less). The method is
not applicable for use in moraines, alluvium, and other depositional
soils.
PLANNING CRITERIA
o A dozer, equipped with a special blade containing a series of
10-inch square grooves and positioned at the same angle as the
cut, shall serrate the slope along the contours.
° Serrations shall be approximately horizontal but may parallel the
roadway grade if it is less than 2 percent.
° Excavation of each series of serrations shall be in the opposite
direction from the preceding one to minimize buildup of loose
material at the ends of the steps.
° Loose material collected at the ends of steps shall be removed
and the ends blended into the natural ground surface.
0 Where rock too hard to rip is encountered, serrations shall be
blended into the rock.
o Material which falls into the ditchline or roadway and rock frag-
ments greater than one-third the shelf width shall be removed.
0 Serration of slopes composed of material that weathers rapidly
shall be completed early in the summer to allow sloughing of
material off the step face prior to fall revegetation to prevent
smothering seed or seedlings.
o A slope bench shall be constructed at the bottom of the slope face
as shown in Control Technique II.
-------
Revegetation shall be accomplished within 7 days following slope
serration using appropriate methods. In decomposing material
which sloughs readily, revegetation shall be delayed until at least
30 days following the slope serration.
MAINTENANCE
Inspect periodically for damage from surface runoff and seepage. Revege-
tation shall be accomplished as required on serrated slopes with excessive
sloughing.
COST
The unit cost for slope serration is $340.00 to $360.00 per acre.
-------
CONTROL TECHNIQUE KK
SLOPE STEPPING
DEFINITION
The construction of a continuous series of horizontal steps on the face
of cut slopes.
PURPOSE
To reduce uninterrupted slope length and provide slope stabilization.
APPLICABILITY
Used in new construction on cut slopes in soft rock which can be exca-
vated In ripping.
Slope stepping is not practical in cuts with soft rock laminations In
thin layers oriented so that the strike is approximately parallel to
the slope face and the dip approximates the stake slope line. Slope
steps are larger than slope serrations and are used on larger slopes.
PLANNING CRITERIA
Slope stepping shall be used to reduce the uninterrupted slope face
length.
0 Cuts in soft rock shall be excavated in a stepped pattern as
shown in Figure KK-1.
° The steps may vary from 2 to 4 feet vertically. The horizontal
dimension shall be equal to the slope ratio times the steprise
height.
0 The upper step shall begin immediately below the soft-rock line
and continue to the bottom of the slope.
8 Steps shall be approximately horizontal but may parallel the road-
way grade if it is less than 2 percent.
° Steps shall have approximately vertical back slopes.
° Excavation of each step shall be in the opposite direction from
the preceding one to minimize buildup of loose material at the
ends of steps.
° Loose material which collects at the end of steps shall be removed
and the ends blended into the natural ground surface.
° Where rock too hard to rip is encountered within a cut, the steps
shall be blended into the rock.
-------
Scaling need not be performed on the stepped slopes except for re-
moval of rock fragments larger than material which may fall into
the ditchline or roadway.
Slopes shall be revegetated with the appropriate methods immedi-
ately following completion of construction of final grade. Suffi-
cient funds shall be allocated to provide for substantial mainten-
ance of revegetation for at least three years following the first
revegetation attempts.
Construction of downdrains may be required to convey surface run-
off from the steps to the base of the slope without erosion.
This must be determined by an analysis of the local site conditions.
MAINTENANCE
Inspect periodically for damage. Excessive surface runoff or seepage
must be controlled with appropriate drainage facilities. Damaged areas
should be revegetated immediately.
COST
The unit cost for slope stepping is $450.00 to $500.00 per acre.
-------
Top of cut
grade
Profile grade
ELEVATION
no scale
(T) Staked slope line
(?) Steprise height 2-4 feet
(D Step tread width = Slope ratio x steprise
(4) Step termini width - '/t steP tread
(5) Overburden
© Slope rounding
(?) Original grade line
Soft rock line - rippable
Slope
bottom bench
SECTION
no scale
SLOPE STEPPING
FIGURE KK-I
-------
CONTROL TECHNIQUE LL
VEGETATIVE STABILIZATION
DEFINITION
The general rules which apply to all planting and seeding operations.
PURPOSE
To enhance the success of revegetation, and to establish an understanding
of the_basic requirements of a successful revegetation program, be it for
temporary or permanent stabilization of disturbed areas.
APPLICABILITY
All revegetation in the Upper Eagle Valley.
PLANNING CRITERIA
Seeding and planting information:
o Annual grasses and legumes are recommended for quick cover and
rapid, temporary protection. Perennial grasses and legumes are
for continued protection, as are wattling, shrub, and tree plant-
ings .
• All grass, legume, herb, shrub, and tree stock used in revegetation
projects in the Upper Eagle Valley shall be of demonstrated
viability and effectiveness in erosion control and soil stabiliza-
tion projects.
0 All legume seed shall be innoculated with appropriate bacteria.
0 Trees and shrubs will provide lasting vegetative stabilization and
protection after the grasses and legumes decline.
0 Shrubs and trees used in revegetation shall match the vegetation
existing on or near the site in species composition and density.
0 Native shrubs, trees, and herbs are recommended in order to main-
tain the biological integrity of the area being revegetated.
• Unless otherwise stated, shrub and tree plantings may be of stock
grown either from cuttings or from seed.
o Bare root planting rates shall be 25 percent higher than the
rates for potted stock.
Site evaluation and modification of vegetation methods:
0 Existing soils survey reports shall be consulted for each revegeta-
tion site or area. All major sites of over fifty acres shall be
-------
inspected and tested by a soil specialist for the following param-
eters: soil depth, pH, percolation, water holding capacity, and
nutrient levels. Specific fertilization specifications recommended
by the soil specialist shall be incorporated into the vegetation
process.
° When soil pH is less than 5.5, that is, the soil is highly acid,
seedling establishment may be retarded. To establish a more
favorable soil pH, lime or other acceptable soil conditioners
shall be applied and incorporated into the top 4 inches of soil.
0 When frost heave potential is determined to be moderate or high,
the following precautions shall be taken:
0 Planting and seeding shall be conducted only from May 1 to
August 1. Supplemental irrigation will be required for
germination and establishment. Timing of irrigation shall
be according to the schedule specified in the erosion con-
trol plan.
0 Mulch rates shall be increased 50 percent over those speci-
fied in Control Techniques W through AA.
0 Areas damaged by frost heave shall be repaired as necessary
with mulch rates fifty percent higher than originally applied.
9 Followup applications of fertilizer shall be made each
spring for two years.
Materials:
° Some seed requires pretreatment prior to planting. Check with
seed suppliers to ascertain the need and to acquire treated seed*
° Shrubs and trees may be seeded or planted from bare root or potted
stock.
" Bare root shrub and tree seedlings shall be kept bundled and in
cold storage from time of receipt until planting.
° Potted shrub and tree seedlings shall be stored in shade out-of-
doors , and shall periodically be lightly sprinkled with water to
maintain soil moisture from time of receipt until planting, which
shall not exceed 30 days.
0 When peat pots, paper pots, or plastic fiber containers are used,
the pot may be planted with the seedling. Peat pots shall be
covered with soil or trimmed to the soil line to prevent the pot
from wicking moisture from the roots of the seedling. Pots shall
not be buried more than 1/2 inch above the top of the pot. De-
pending on the planting method used, plastic fiber containers
may be planted with up to 3 inches of the container above the sur-
face as shown in Figure LL-1
0 When metal containers are used, the container shall be removed prior
to planting. Careful removal of the pot will prevent damage to the
the root mass. The root mass and enclosed soil shall be loosened
gently by hand followed removal from the pot. The plant shall then
be planted immediately.
-------
Irrigation
Irrigation shall be supplied wherever possible. Soil shall be
wetted to field capacity to a depth of 3 to 4 inches at time of
planting and each time the soil moisture drops below the permanent
wilting percentage.
Irrigation water shall not applied at rates which result in
erosion of the soil surface or damage to planted or seeded
areas.
When irrigating, care should be taken to insure a uniform moistening
of the slope to prevent patchiness. Irrigation shall cease before
any area becomes saturated or wetted above field capacity.
If portions of the slope vary in availability of water (springs,
creeks, etc.), revegetation will be designed to place more water-
tolerant species in the wetter areas and more drought-resistant
species in drier areas.
Irrigation shall be continued during the first year after planting.
Irrigation shall be reduced in the following year, and in the
third and ensuing years. After the third year, irrigation shall
only be used to prevent failure of a revegetation project during
extremely dry periods.
Scheduling of work:
All revegetation work shall be accomplished between the dates of
May 1 and September 15 of a given year. Early spring is the most
favorable period. Late fall plantings will require significant
maintenance and further revegetation in the following spring, but
a late fall planting with mechanical stabilization is preferable
to leaving a site bare over a winter.
South-facing slopes shall be seeded only in springtime or summer if
irrigation is available to avoid frost heave and freezing of the
seedlings. North-facing slopes may be seeded in fall.
Work shall be scheduled to minimize the time of exposure of bare
soil and partially completed work.
Personnel:
It is desirable for maintenance personnel who are inspecting re-
vegetated sites to be equipped with straw, grass seed, fertilizer,
and hand tools to allow on-the-spot repair of damaged areas.
Revegetation labor forces shall be under the direction of a person
familiar with the technique being used.
Proper instruction of the labor force is vital and may be obtained
from the U.S. Soil Conservation Service, a University Extension
agent, or professional nursery persons.
-------
SELECTION OF VEGETATION TECHNIQUES
Alternative vegetation methods for various general site conditions are de-
signated in Table LL-1. Description of various alternative vegetation
methods referred to in Table LL-1 are given in Table LL-2.
SELECTION OF SEED AND LIVE PLANTS
There is a fairly wide choice of grasses, legumes, forbs, shrubs, and
trees from which to choose. If a high level of management can be provided,
the range of plants which can be used is broader. Final selection should
be based on adaptation of the plants to the soils and climates suitability
for the specific use, ease of establishment, longevity or ability to re-
seed, and the maintenance required. Mosf introduced plants require a
high level of maintenance while adapted native plants generally require
less cultural treatment for maintenance. On steep slopes and other in-
accessible areas, it is preferable to select plants requiring little or
no maintenance. Contact Che U.S. Forest Service, Soil Conservation Ser-
vice, or local Soil Conservation District for assistance.
Temporary Vegetation
Earth moving activities such as heavy cutting, filling, and grading are
generally performed in several stages; they are often interrupted by long
periods during which the land lies idle and is subject to accelerated
erosion. Also, final land grading may be completed during a season not
favorable for immediate establishment of permanent vegetation. Such sites
can be temporarily stabilized by establishment of rapid—growing annual
grasses such as rye, ryegrass, sudangrass, and similar species. These
plants provide quick protective cover and can later be worked into the
soil and mulch when the site is prepared for establishing permanent vegeta-
tion. When it is not practical to plant temporary vegetation, use mulch
materials to provide the required protection. Species, planting time, and
seeding rate for temporary vegetation are given below.
Specie Seeding Time Seeding (lbs/acre)
Ryegrass Spring and fall 30
Oats Spring and fall 90
Cereal rye Spring and fall 60
Wheat Fall 90
Barley Spring and fall 90
Millet Spring and summer 40
Permanent Vegetation
When areas are ready for planting to perennial cover, special care should
be taken in selecting the types of plants to use. The species of plants
presented herein presume non-irrigated areas and are adaptable to the
Upper Eagle Valley. However, irrigation for the first to third years
will aid establishment. Other plant species which are irrigation dependent
for survival or appearance as in urban landscaping may be used. See
Tables LL-3 and LL-4.
-------
TABLE LL-
-1
VEGETATION AND SLOPE STABILIZATION METHOD
SELECTION TABLE1
Existing
Percent
Rock
Slope
Vegetative
and Stone Ex-
Face
Vegetation Method
Slope Type
Gradient
Cover^
posed on
Surface
Length
Site Conditions
Components
Cut, fill and
4:1 or
None
<10-30%
<10'
A
Seed and mulch
other dis-
flatter
>10'
B, C, D
Seed and mulch or
turbed areas.
NA3
plantings
>30%
A&D, B&D, C&D
Seed and mulch and
plantings
Partial
Na3
NA
D
Plantings
Complete
NA
NA
None^
-
4:1-2:1
None
<10%
<10'
A,C,F,G,D
Seed and mulch or
plantings
NA
10-20'
N, 0, P
Seed and mulch and
plantings
>20'
H, I. J
Wattling; seed and
mulch and plantings
Partial
NA
NA
D
Plantings
Complete
NA
NA
None
-
2:1-
None
NA
NA
K. L. M
Slope stabilization;
1.5:15
seed and mulch and
plantings
Partial
NA
NA
K. L. M
Slope stabilization;
seed and mulch and
/.
plantings
Complete
NA
NA
None
-
-------
TABLE LL-1
VEGETATION AND SLOPE STABILIZATION METHOD SELECTION TABLE1(Continued)
Slope Type
Gradient
Existing
Vegetative
Cover2
Percent Rock
and Stone Ex-
posed on Surface
Slope
Face
Length
Vegetation Method
Site Conditions Components
Unstable
Drainage
All
Conditions
<2:1
>2:1
NA
NA
NA
NA
NA
NA
None^
BMP Chapter VIII Runoff control on
slopes
Temporarily
Inactive
Construction
Sites
All
Conditions
<2:1
None
or
Partial
NA
NA
Q, R Mulch
Active
Construction
Sites
All
Conditions
<2:1
None
NA
NA
Q Mulch
1 Enter the table from left to right following the appropriate site conditions to select the proper revegeta-
tion method for the site.
2 Areas of distinctly different existing vegetation coverage shall be evaluated separately.
The terms "none," "partial," and "complete" have the following meanings:
None = 0-20% coverage of the site
Partial = 20-50% coverage of the site
Complete = >50% coverage of the site
3 NA means that the condition does not affect the selection of a revegetation method.
4 Method E is required where drainageways are eroding or threatening to destabilize established vegetation.
-------
TABLE LL-2
DESCRIPTION OF VEGETATION METHODS
Note: Designations indicate the specific Best Management Practice to use,
IN THE EXACT SEQEUNCE IN WHICH THE WORK IS TO BE PERFORMED, except
that the fertilizer which is to be used is always specified last.
For Example:
Alternative A, as does every alternative, requires the use of seed
and live plant type quality and quantity. It then requires that
seedbed preparation be accomplished by hand, followed by hand
broadcasting of seed. Straw mulch is to be punched by hand on
the slope, maintenance procedures are specified, and finally the
fertilizer required by the seeding is specified.
STEP-BY-STEP DESCRIPTION OF VEGETATION METHODS
Site Condition Operation in Order of Performance ($/Acre)
A
Small slopes with
Grass, legume, shrub, and tree
seed
gradients as steep
selection
220
as 2:1
Seedbed preparation, by hand
220
Broadcasting seed, hand labor
70
Straw mulch, hand punching
540
Maintenance
_1
Fertilizer
150
Total
$1
.200
B
Small slopes with
Grass, legume, shrub, and tree
seed
gradients as steep
selection
220
as 4:1
Seedbed preparation by machine
80
Drilling seed
30
Straw mulch by machine (CTE Z)
200
Maintenance
-
Fertilizer
150
Total
$
680
C
Small slopes with
Grass, legume, shrub, and tree
seed
gradients as steep
selection
220
as 2:1
Seedbed preparation, some hand
labor
120
Hydromulching (CTE W)
920
Hydroseeding, combined with hydromulching
220
Maintenance
-
Fertilizer
150
Total
$1
.630
1 indicates cost is not included in revegetation; allow 25 percent
of total for the method over a 3- to 5-year period following initial
revegetation.
-------
TABLE LL-2 (Continued)
STEP-
-BY-STEP DESCRIPTION OF VEGETATION METHODS
Site Condition
Operation in Order of Performance
($/Acre)
D
Slopes with
Vegetative plant selection
$2,940
gradients as
Planting
580
steep as 2:1
Maintenance
-
Fertilizer
40
$3,560
E
Unstable drain-
Grass and legume seed selection
80
ageways as steep
Seedbed preparation, some hand labor
120
as 2:1 which do
Broadcasting seed by machine
210
not require BMP
Straw mulch, machine punching (CTE Z)
200
Chapter IX
Matting in drainageways (CTE DD)
3,350
Maintenance
-
Fertilizer
150
Total
$4,110
F
Small slopes
Grass, legume, shrub, and tree seed
as steep as 2:1
selection
220
Seedbed preparation, some hand labor
120
Hydroseeding
310
Fiberglass roving (CTE Y)
1,800
Maintenance
-
Fertilizer
150
Total
$2,600
G
Small slopes as
Grass, legume, shrub, and tree seed
steep as 2:1
selection
220
Seedbed preparation, some hand labor
120
Broadcasting seed by machine
40
Straw mulching by machine (CTE Z)
200
Jute matting (CTE BB)
3,520
Maintenance
-
Fertilizer
150
Total
$4,250
H
Large slopes as
Grass and legume seed; shrub and tree
steep as 2:1
plant selection
3,020
Seedbed preparation, some handlabor
120
Wattling
2,550
Hydromulch (CTE W)
950
Hydroseeding, combined with hydromulching
220
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$7,630
-------
TABLE LL-2 (Continued)
STEP-
-BY-STEP DESCRIPTION OF VEGETATION METHODS
Site Condition
Operation in Order of Performance
($/Acre)
I
Large slopes as
Grass and legume seed; shrub and tree
steep as 2:1
plant selection
3,020
Seedbed preparation, some hand labor
120
Wattling
2,550
Hydros eeding
310
Fiberglass roving (CTE Y)
1,800
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$8,570
J
Large slopes as
Grass and legume seed; shrub and tree
steep as 2:1
plant selection
3,020
Seedbed preparation, some hand labor
120
Wattling
2,550
Hydroseeding
310
Straw mulch (CTE Z)
200
Jute matting (CTE BB)
3,520
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$10,490
K
Slopes needing
Slope stabilization, as needed BMP
mechanical
Chapter VI
-
stabilization
Grass and legume seed; shrub and tree
3,020
plant selection
Seedbed preparation, moderate hand labor
160
Hydromulch (CTE W)
950
Hydroseeding, combined with hydromulching
210
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$5,110
L
Slopes needing
Slope stabilization, as needed, BMP
mechanical
Chapter VI
-
stabilization
Grass and legume seed; shrub and tree
3,020
plant selection
Seedbed preparation, moderate hand labor
160
Hydroseeding
310
Fiberglass roving (CTE Y)
1,800
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$6,060
-------
TABLE LL-2 (Continued)
STEP-
•BY-STEP DESCRIPTION OF VEGETATION METHODS
Site Condition
Operation in Order of Performance
($/Acre)
M
Slopes needing
Slope stabilization, as needed, BMP
mechanical
Chapter VI
-
stabilization
Grass and legume seed; shrub and tree
3,020
plant selection
Seedbed preparation, moderate hand labor
160
Broadcasting seed, by hand
70
Straw mulch, machine method (CTE Z)
200
Jute matting (CTE BB)
3,520
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$7,740
N
Slopes to 20'
Grass and legume seed; shrub and tree
long, as steep
plant selection
3,020
as 2:1
Seedbed preparation, moderate hand labor
160
Hydromulch (CTE W)
950
Hydroseeding, combined with hydromulching
220
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$5,120
0
Slopes to 20'
Grass and legume seed; shrub and tree
long, as steep
plant selection
3,020
as 2:1
Seedbed preparation, moderate hand labor
160
Hydroseeding
310
Straw mulch (CTE Z)
200
Jute matting (CTE BB)
3,520
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$7,980
P
Slopes to 20'
Grass and legume seed; shrub and tree
long, as steep
plant selection
3,020
as 2:1
Seedbed preparation, moderate hand labor
160
Broadcasting seed
40
Fiberglass roving (CTE Y)
1,800
Vegetative planting
580
Maintenance
-
Fertilizer
190
Total
$5,790
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TABLE LL-2 (Continued)
STEP-BY-STEP DESCRIPTION OF VEGETATION METHODS
Site Condition
^ Temporarily
inactive or
active
construction
site
Operation in Order of Performance
Wood chip application (CTE X)
Gravel Mulch (CTE AA)
($/Acre)
$ 680
170
Total $ 850
R Temporarily
inactive
construction
site
Chemicals and tackifiers
$ 830
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TABLE LL-3
Perennial Grasses and Legumes
for Plantings in the Upper Eagle Valley
Species
Soil
3^ and fcxn
osure
Slope over 6:1
Gently
B-Bunch
Mature
North
South
Sloping
Recommended
S-Sod
Height
and
East
and West
to Flat
Variety
Former
(in)
L
C
L C
L C
B
20
X
X
X X
X X
Crltana
S
20
X
X
X X
X X
Nordan
B
24
X
X
X X
X X
Largo
or Joae
B
48
X? X
Amur
S-
30
X
X
X X
X X
Sodar
s
30
X X
Barton
s
20
X
X
X X
X X
Prisiar
B
30
X
X
X x
Luna
s-
30
X
X
X x
X X
B
24
X4 X
Regar
B
24
X
X
X X
X X
Lincoln or
Manchar
S
30
X
X
X x
X X
Bromar
B
36
X
X
X X
X X
Latar
B
36
X
X
X X
Vinall
B
24
X X
Alta
B
36
X
X
X X
Durar
B
12
X
X
X X
X X
15
X
X
X X
X X
36
X
X
X X
X X
S
48
X X
B
30
X
X
X X
S
20
X
X
X X
Creen
Stipagrass
B
30
X
X
10
X
X
x5 X
12
X
X
X X
Madison
24
X
X
X X
X x
Ease
tab!
Adaptability Ratlnp.a^
of Es- Rate of
shment Spread Tolc
It
ranee
Fairway wheatgrass
(Agropyron crlatatum)
Thicksplke vheatgrass
(Agropyron dasvstachyum)
Created wheatgraaa
(Agropyron desertorum)
Tall vheacgrass
(Agroovron elonaatum)
Intermediate wheatgrass
(Agropyron intermedium)
Streambank wheatgrass
(Agropyron riparium)
Western wheatgrass
(Agrophvron smithll)
Slender wheatgraaa
(Agrophvron trachycaulua)
Pubescent wheatgraaa
(Agropyron trlchophorum)
Redcop
(Asroatls alba)
Meadow brome
(Bromua bribersteinni)
Smooth brome
(Brooms inermls)
Mountain brome
(Bromus marginatum)
Orchard grasa
(Dectylia glomerate)
Ruaaian wildrye
(Elyana junceua)
Tall feacue
(Festuca arundinacea)
Hard fescue
(Featuca ovina v.
durluscula)
Alfalfa
(Medicago satlva)
Yellow sweetclover
(Mali.lotus officinalis)
Re*d canarygrass
(Phalarla arundinacea)
Timothy
(Phleum pratenao)
Kentucky bluegrass
(Poa pratenala)
Green necdlegrass
(Stlpa vlrjdula)
Alalka clover
(Trlfollum hybrldum)
Red clover
(Trlfollum pratense)
Hairy vetch
(Vlcia vlllosa)
1 Soils: L~Loamy; C-Claycy.
2 Adaptability Ratings: 1-Poor; 2-Fair;
^Moderate; 4-Cood; 5-Excelliint.
3 Moir.t saline lowlands.
4 Hoist lowlands.
5 Tolerate* poorly drained soil.s.
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TABLE LL-4
Shrub and Trees for Planting
in the Non-Irrigated Areas
of Upper Eagle Valley
Species
Growth
Characteris tics
Hawthorne
(Crataegus spp.)
Russ ian-olive
(Elaeagnus angustifolia)
Honey-locust
(Cleditsia tricanthos)
Pocky Mountain juniper
(Juniperus scopulorum)
Colorado blue spruce
(Picea pungens)
Ponderosa pine
(Pinus ponderosa)
American plum
(Prunus americana)
Skunkbush sumac
(Rhus trilobata)
Lilac
(Syringa vulgaris)
Siberian elm
(Ulmus pumila)
Tall shrub
Tall shrub
Tree
Evergreen tree
Evergreen tree
Evergreen tree
Low shrub
Low shrub
Low shrub
Tree
Trees and shrubs are deciduous unless otherwise
noted.
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Seedbed Preparation
Seed germination and seedling establishment are enhanced by loosening the
surface layers of soil prior to planting. This process can involve either
hand or machine raking of the surface. Best vegetative results are ob-
tained when seed is covered after sowing. After seeding, the area shall
be reraked to only a depth of 1/4-inch to 1/2-inch following the sowing
of seed.
Seedbed Preparation on Cut and Fill Slopes
0 Seedbed preparation shall begin as soon as possible after the soil is
laid bare. Erosion by wind and water deteriorate the soil potential
to support a vigorous stand of vegetation.
0 Seedbed preparation shall immediately precede seeding or planting.
If a large area is involved, planting may proceed on completed por-
tions while preparation progresses to other sections.
0 Clear all rubbish and slash from the slope.
0 Compacted or eroded soil shall be scarified to a depth of 3 to 4
inches, all gullies and rills shall be smoothed, and any associated
fill tamped. Slope scarification shall proceed along the contours
of the slope.
0 Topsoil salvaged from the site at the beginning of grading operations
shall be placed on the finished grade to a depth of at least 4 inches.
0 If construction or erosion have stripped all topsoil from the site,
imported topsoil greatly increases the probability of a successful
revegetation effort.
0 Existing vegetation shall remain undisturbed.
0 On small areas, those with significant rockiness, or those too steep
to allow vehicle access, rake the surface of the soil to a depth of
1/2 inch to 1-1/2 inch using hand tools.
0 On larger areas or those with less rockiness and which allow vehicu-
lar access, draw a spring-toothed or fixed-tooth harrow behind a
tractor to rake the soil surface to a depth of 1/2 inch to 1-1/2
inch.
0 Fertilizer should be applied and worked into the soil immediately
prior to seeding.
-------
Broadcasting Seed
Seeding of grasses, legumes, shrubs, and trees may be accomplished at the
same time, or any of these seed types may be sown separately. Broadcast-
ing seed provides uniformly distributed seed on the soil surface. The
soil must be raked to properly cover the seed and to enhance germination.
Broadcasting seed is particularly adapted to use on steep or rocky sites,
abandoned roadways, or sites with limited access or where hand labor is
used.
0 Breast seeders or "belly grinders" and truck- or tractor-mounted
automatic seeders are preferred for broadcast seeding where they
can be used. A more uniform application results from the use of
these devices than from hand broadcasting. Hand broadcasting works
well for maintenance seeding and seeding small areas.
0 Broadcasted seed must be lightly raked and covered with a shallow
layer of soil between 1/4 and 1/2 inch thick. This soil cover
protects the seed and helps germinating seeds take root. Raking
should begin immediately following seeding, and requires only a
garden type rake for small areas. Agricultural rakes or spring-
toothed harrows set very lightly will work for large, flat, or
gently sloping areas. Hand raking is required on steep slopes re-
gardless of size of the area.
Drilling Seed
Drilling of grass, herb, shrub, and tree seeds provides the maximum
possibility of successful germination and -rowth with the minimum in-
vestment in labor, seed, and fertilizer. Mixture proportions can be
accurately managed and a uniform planting at the correct rate can be
achieved.
0 Prior to drilling of seed, the entire area should be disked with
a heavy disk equipped with serrated blades. Disking shall be
along the contours in any sloping areas.
0 Disking and drilling may be conducted in the same pass.
0 All seeds may be mixed prior to planting, unless extreme differences
in size would prevent the proper operation of the drill. In the event
seed sizes differ radically, separate passes should be made to plant
different size groups or seed may be separated into alternate bins
in the drill.
0 Calibrate the drill by counting the number of seeds in at
least three 5-foot sections of drill rows.
° Check the seedling rate periodically during seeding operations
and adjust the rate as necessary.
-------
o Fertilizer of the specified formulation shall be applied at the rate
specified in BMP XI-K.
° Drilling shall be conducted as quickly as possible upon completion
of grading on a construction site.
° The edges of drilled areas shall be broadcast seeded to complete
the seeding.
P.ydroseeding
Hydroseeding involves placing seed, fertilizer, a tacking agent, and
water with a small amount of dyed wood fiber into a tank and agitating
the mixture into a uniform slurry. This slurry is sprayed upon the
site. This technique is preferred for steep sites or sites where access
by equipment is limited.
Hydroseeding applies the seed directly to the soil surface. A mulch
must then be applied on the surface and raked to cover the seed with
soil. Hydroseeding and hydromulching can be used ia two separate
operations on the same site to provide the most effective application
of seed and a mulch blanket, but the cost increases with a two-stage
seeding and mulching operation.
Hydroseeding is usually combined with hydromulching to apply both
seed and mulch to the site at one time. The mulch used is a wood fiber
which has been dyed to aid in uniform application. The major short-
coming of combining the two procedures is that a significant proportion
of the seed is suspended in the mulch blanket and does not come into
contact with the soil. This reduces the effectiveness of the seeding
method.
• The hydroseeder shall be equipped with a gear-driven pump and a
paddle agitator. Agitation by recirculation from the pump is not
allowed. Agitation shall be sufficient to produce a homogenous
slurry of seed, fertilizer, and tacking agent in the designated
proportions.
0 Water shall be applied at a rate of 3,000 gallons per acre.
° One hundred fifty pounds per acre of wood fiber shall be added to
aid uniform application.
Tacking agent shall be applied at 200 gallons of wet ingredients per acre
or 80 pounds of dry ingredients per acre.
Fartilizer of the specified formulation shall be included at the speci-
fied rate.
0 Some slow—release granular fertilizers may sink rapidly and
cause plugging of the pump or hoses. Both the hydroseeder manu-
facturer and the fertilizer manufacturer should be consulted re-
garding the appropriateness of the fertilizer for hydroseeder
applications.
° If the fertilizer cannot be applied using the hydroseeder, broadcast
using methods presented.
-------
Seed mixtures shall be included at the specified rate. No seed
shall be added to the slurry until immediately prior to beginning
the seeding operation. The time allowed between placement of seed
in the hydroseeder and emptying of the hydroseeder tank shall not
exceed 30 minutes.
Vegetative Planting
Many shrubs and trees are difficult to establish from seed in natural
environments, and natural seed crops vary videly from year to year.
Rapid invasion from native vegetation and rapid establishment of sown
seed of woody species i3 therefore unreliable. Vegetative plantings are
used to provide living shrubs and trees erosion control faster than seeds
to woody species can germinate and grow to these dimensions.
Extremely rocky slopes or areas which have significant quantities of
natural vegetation are difficult to seed and mulch effectively. Vegeta-
tive plantings can be used in these situations to provide additional
stabilization.
Vegetative plantings of native species provide long-term soil stabiliza-
tion which is aesthetically harmonious with natural vegetation and
which requires little long-term maintenance. Short-term maintenance is
necessary to ensure the establishment of the vegetation.
• Vegetative planting may be combined with seeded grasses and legumes
which provide immediate surface coverage.
a Vegetative plantings shall be of species which are native or
adaptable to the Upper Eagle Valley.
° Planted material may be grown from either cuttings or seed and may
be potted (containerized) or bare root stock.
« Store bundled bare root planting stock, whether tree or shrub
species, in a cool, moist place from time of receipt until
time of planting. This time shall not exceed 10 days.
° Store potted planting stock in shade, out-of-doors, and keep
lightly sprinkled with water to maintain a moist soil from
the time of receipt to the time of planting. This time shall
not exceed 30 days.
° Irrigation of vegetative plantings during the first two years fol-
lowing planting is required to increase the survival rate. The
soil shall be wetted to field capacity to a depth of 3 to 4 inches
at the time of planting and each time the soil moisture level drops
below the permanent wilting percentage.
° Voluntary or unskilled labor may be used in planting. However,
a supervisor who is skilled in the techniques being used should
direct the labor.
-------
The following procedure shall be used:
a Basins 12 inches in diameter and depressed no more than 2 inches
from the elevation of the downslope lip shall be constructed (see
Figure LL-1).
o The plant shall be placed near the downslope lip as shown in Figure
LL-1. This allows sloughing from the slope to fall into the basin
without burying the yound plant.
0 Holes shall be opened with a planting bar or shovel as shown in
Figure LL-1.
o Apply fertilizer at the rate specified.
° Plants shall be placed in the planting holes so that the crown of
the plant is at the surface of the soil. No air space shall be
allowed around the roots, nor shall the roots be folded under, as
shown in Figure LL-1.
0 Tree species may be of bare root stock or of potted stock. Pots
should be one-gallon size or larger.
0 Shrub species may be of bare root stock or of potted stock. Pots
shall be as specified below.
° The preferred planting pot is composed of a tube of woven
plastic which is planted with the plant contained in it.
The pot deteriorates over time (Conwed or equivalent). The
pots shall be 2 inches in diameter and 12 inches long, with
both ends open. Use 9 inches of potting medium to grow the
individual, with 3 inches of the tube rising above the potting
mixture. The upper portion provides rodent protection when
the stock is planted.
° Peat pots are not recommended since research has shown greater
mortality of plantings in peat pots due to drying. If peat
pots are used, any exposed peat pot material showing after
planting shall be removed.
0 No container shall be less than 2 inches wide and 6 inches deep.
0 The growth medium shall approximate the soil type on the revegeta-
tion site.
° If bare root stocks are used, planting rates shall be increased by
1.25 times the stated rate.
° Wood chip or wood fiber mulch shall be placed to a depth of 2 inches
around each plant.
Effectiveness of Seeding Methods
Broadcasting seed provides an effective method of scattering seed uni-
formly. If the seed is properly covered with soil and appropriate mulches
and irrigation are applied, germination and establishment are generally
better from broadcasted seed than from seed sown by hydroseeding, but not
as good as the germination and establishment from drilled seed due to the
difficulty of properly covering all of the seed on any but the most ideal
-------
sites. However, broadcasting seed is approximately equivalent to
hydroseeding in effectiveness.
Drilling is the most effective method available for properly plant-
ing seed on sites where drills can be used.
On ideal sites, hydroseeding is equally effective in uniformly
scattering seed as is broadcasting seed, but is not as good as
drilling seed. However, it is appropriate to more different sites
it can provide more uniform application rates than broadcasting.
Since vegetative planting places living plants on a site, thus de-
creasing the length of time necessary to establish a complete re-
vegetation. Adequate maintenance is absolutely necessary to achieve
this effectiveness since vegetative plantings require irrigation
for at least the first year, and will benefit from irrigation for
two or more years.
-------
,\o
Planting location
inside basin but near
downslope lip
Planting basin
Planting bar
©
Preparation of planting hole using planting bar (Dibble)
£
Correct ly
planted
Roots
folded
Air space
|
Too
shallow
Incorrectly planted
PLANTING SCHEMATIC
FIGURE LL-I
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO. 2.
EPA-908/3-80-001B
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Upper Eagle Valley Nonpoint Source
Assessment and Control Plan
Volume 2 Nonpoint Source Control Techniques
5. REPORT DATE
Fphrnary IQftfl
6. PERFORMING ORGANIZATION COOE
7. AUTHOR(S)
Mr. Phillip J. Morris
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME ANO ADDRESS
Engineering - Science
125 West Huntington Drive
Arcadia, California 91006
10. PROGRAM ELEMENT NO.
Final
11. CONTRACT/GRANT NO.
68-01-4611
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
1860 Lincoln Street
Denver, Colorado
13. TYPE OF REPORT ANO PERIOD COVERED
14. SPONSORING AGENCY COOE
IB. SUPPLEMENTARY NOTES
16. ABSTRACT
This volume of the Upper Eagle Valley Nonpoint Assessment and Control Plan con-
tains information and descriptions of nonpoint source control techniques which can
be employed in the Upper Eagle Valley. The control techniques presented and the
information contained in this report cannot substitute for good project planninq.
They can only mitigate the consequences of bad planning. In concert with good
planning and enforcement, they can reduce nonpoint source pollution problems.
Planning aspects are addressed in Section VII, Volume 1 of this report.
17. KEY WORDS AND DOCUMENT ANALYSIS
a- DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Nonpoint Sources
Water Pollution Control
Water Runoff
Snowmelt
Runoff
Storm Water Drainage
St.nrm Water Runoff
Upper Eagle Valley, Co.
Best Management Practices
18. DISTRIBUTION STATEMENT
Distribution Unlimited
19. SECURITY CLASS (This Report)
Unclasc-ifioH
Ufi
20. SECURITY CLASS (This page)
Unclassified
22. PRICE ~
EPA Form 2220-1 (R»». 4-77) prkvious bdition is oeiOLtTi
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