Stormwater Manual - Pima County Flood Control District

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9.4 Bioengineering Techniques Bioengineering techniques for streambank protection utilize native vegetation in combination with inert structural materials to stabilize soils that are subject to erosion and shallow mass movement. 9.4.1 Design Criteria Establishing permanent vegetation is the preferred method for stabilizing soils along streambanks. With proper installation and maintenance, the planting of rooted stock, cuttings and direct seeding of native vegetation, in combination with erosion control fabrics, will effectively stabilize soils on slopes of 3:1 or flatter along streams with low flows and no concentrated discharges over the face of the streambank. On streambank slopes of 3:1 or steeper, the techniques described in the following sections (with exception of the Live Staking technique) shall be employed as needed. Each technique is discussed in order of increasing effectiveness of protection based upon the slope of the streambank. The combined use of two or more techniques to accomplish streambank stabilization and protection may be applicable for some sites. When streambanks must be disturbed, slopes shall be regraded to match the adjoining upstream and downstream slopes, if they are stable. If the adjoining slopes are not stable, the disturbed portion shall be regraded to the least gradient possible. Reinforcement shall be provided at the base or toe of the streambank below the mean low waterline prior to implementing bioengineering techniques. Several techniques discussed are applicable for base reinforcement. All work shall begin at the base of the streambank and continue up gradient. For sites involving the discharge of concentrated flow through a streambank and directly into a stream, protection shall be provided for the streambank opposite of the concentrated discharge. Most of the techniques discussed below will be applicable for those sites and are duly noted. 9.4.2 Live Stake Live stakes shall be used in limited situations for streambank slopes of 3:1 or flatter with low flows and no surficial overbank discharge. This technique consists of inserting (tamping) fresh hardwood cuttings into the streambank. This technique is more applicable as a preventive measure before severe erosion problems occur. Live hardwood cuttings shall be collected and installed during the dormant season (November through March) from areas near the site. Drainage ditches, detention ponds, and construction sites can be good sources for materials. The following table provides recommended species for hardwood cuttings. Table 9-1 provides the recommended species for rooted seedlings. STORMWATER MANUAL 9-9 January 1, 2009 LEXINGTON-FAYETTE CO., KY.
TABLE 9- 2 NATIVE PLANT SPECIES SUITABLE FOR HARDWOOD CUTTING IN CENTRAL KENTUCKY Common Name Primary Species: Black willow Sandbar willow Heart-leaf willow Silky dogwood Redosier dogwood American elderberry Secondary Species: Tall pussy willow Silky willow Dwarf willow Alternate-leaf dogwood Gray dogwood Rough-leaf dogwood Boxelder Nannyberry Swamp Haw Arrowwood Scientific Name Salix nigra Salix interior Salix rigida Cornus amomum Cornus sericea Sambucus canadensis Salix discolor Salix sericea Salix humilis var. macrophylla Cornus alternifolia Cornus racemosa Cornus drummondii Acer negundo Viburnum lentago Viburnum nudum Viburnum dentatum Other practices, in combination with live stakes, shall be used for streambanks that receive high flow fluctuations or consist of fill soils. Stakes (cuttings) shall be 2 to 3 feet in length and 0.5 to 2 inches in diameter with all outer branches removed. Basal end (inserted into ground) shall be sawed clean at an angle. Blunt end (exposed end) shall be cut square. See Figure 9-4A for a live stake detail. Stakes shall be installed within 24 hours of cutting. Temporary storage shall occur in a moist, cool location. Stakes shall be installed at right angles to the slope with 20 percent (1/5) of the stake left exposed. Stakes shall be spaced at a minimum of 2 to 4 per square yard and in a random configuration. Installation shall begin at the base of the streambank working up gradient. Dead blow hammers work the best for installing stakes in soft soils. In cases where stiff soils exist, then pre-drilled holes must be used to accommodate cutting installation. The ground at the base of each stake shall be tamped firm. When erosion control fabrics are necessary, the live stakes shall be used to help secure the material to the face of the streambank. STORMWATER MANUAL 9-10 January 1, 2009 LEXINGTON-FAYETTE CO., KY.
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Stormwater Manual Lexington-Fayette
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1.1 Introduction Chapter 1 gives th
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1.3 Definitions 1.3.1 Public Draina
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• the Division of Engineering det
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• Masterson Station Watershed hyd
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• only one corporation or busines
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1.5 Water Quantity Criteria for New
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TABLE 1- 1 OPTIONS FOR STORMWATER M
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TABLE 1- 2 FLOW CRITERIA FOR STORMW
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contained in Chapter 10. The water
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1.7.4 Water Quality Criteria for Re
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• new development commercial site
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CHAPTER 2 PERMITS
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2.1 Land Disturbance Permit 2.1.1 P
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If the analysis described in the de
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2.3 Kentucky Division of Water KPDE
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2.5 401 and 404 Permits - Kentucky
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3.1 Introduction Watershed studies
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• detailed description of any nat
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3.3 Runoff Models 3.3.1 General The
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3.4 Post-Development Floodplain Ana
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APPENDIX 3-A - SOURCES OF DATA
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National Oceanography and Atmospher
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Pond/Culvert Inventory Data Sheet P
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4.1 Overview 4.1.1 Introduction An
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4.3 Improvement Plans 4.3.1 50 Perc
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• culvert outlet appurtenances an
Page 57 and 58: 4.4 Record Drawings A record drawin
Page 59 and 60: 5.1 Introduction 5.1.1 Purpose The
Page 61 and 62: 5.3 Design Rainfall Event 5.3.1 Sin
Page 63 and 64: TABLE 5- 2 GREEN-AMPT INFILTRATION
Page 65 and 66: 5.5 Stormwater Management Model (SW
Page 67 and 68: TABLE 5- 4 MANNINGS N FOR OVERLAND
Page 69 and 70: APPENDIX 5 A DESIGN STORM DISTRIBUT
Page 71 and 72: 6-HOUR RAINFALL DISTRIBUTIONS Cumul
Page 73 and 74: 100-YEAR - 24-HOUR RAINFALL DISTRIB
Page 75 and 76: CHAPTER 6 INLETS / STORM SEWERS / M
Page 77 and 78: 6.1.4 Storm Sewers Storm sewers sha
Page 79 and 80: For d ≥ 1.0’, use the orifice f
Page 81 and 82: 6.4 Construction Specifications All
Page 83 and 84: 7.1 Introduction As used in this ma
Page 85 and 86: 7.2.6 Culvert Skew A culvert shall
Page 87 and 88: Barrel Area and Shape Barrel area i
Page 89 and 90: 7.5 Bridge Design Procedures Use HE
Page 91 and 92: CHAPTER 8 CONSTRUCTED CHANNELS
Page 93 and 94: 8.2 Permanent Constructed Channels
Page 95 and 96: The earth fill materials used to co
Page 97: 8.3 Paved Channels A paved channel
Page 100 and 101: 9.1 Introduction The streams of Fay
Page 102 and 103: 9.2.3 Material Specifications Veget
Page 104 and 105: TABLE 9- 1 SUGGESTED RIPARIAN SPECI
Page 106 and 107: 9.3 Riparian Buffer Zones 9.3.1 Gen
Page 110 and 111: 9.4.3 Root Wad Revetment Root wad r
Page 112 and 113: Dead stout stakes shall be installe
Page 114 and 115: Willow tree species are the best fo
Page 116: 9.5.3 Maintenance All structures sh
Page 129 and 130: 10.1 Introduction Non-point source
Page 131 and 132: TABLE 10- 1 WATER QUALITY DEPTH VER
Page 133 and 134: Grade the top of the planting soil
Page 135 and 136: 10.4 Infiltration Systems Infiltrat
Page 137 and 138: Design Criteria To be considered a
Page 139 and 140: If desired, large infiltration basi
Page 141 and 142: When the contributing area draining
Page 143 and 144: Provide sufficient access to the de
Page 145 and 146: Select underdrain gravel to meet AA
Page 147 and 148: Compute the total surface area of b
Page 149 and 150: 10.6 Prefabricated Treatment Device
Page 151 and 152: landscaping plan for the pond and t
Page 153 and 154: When necessary, compact subgrade su
Page 155 and 156: After the embankment has been built
Page 157 and 158: Embankment heights shall not exceed
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10.9 Wet Ponds In this manual, wet
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Q = A (2gH) 0.5 /(1 + K e +K b + K
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Provide a drain with a valve at the
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CHAPTER 11 EROSION AND SEDIMENT CON
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11.1 Purpose This chapter describes
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1. The limitations on coverage set
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11.2.2 Non-Structural Practices Thi
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Figure 11-1. “Seed mats” may be
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peak discharges during construction
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Locations of proposed controls, uti
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11.4 Structural Soil Stabilization
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When using a mulch net, it shall be
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Material Specifications Seed shall
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Material Specifications Soil materi
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11.4.5 Road/Parking Stabilization R
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To reduce maintenance and loss of a
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Effective netting and matting requi
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Maintenance Outlets shall be inspec
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Temporary or permanent seeding and
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A standard flared end section or a
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11.5 Structural Sediment Control BM
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The amount of sediment entering a t
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Detention storage shall be provided
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The emergency spillway shall have a
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PHYSICAL PROPERTY Filtering Efficie
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Fasten fabric securely to the stake
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SEEDING MIXTURE AND SITE SUITABILIT
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Upon removal of the structure, the
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11.5.10 Concrete Washout Pits Concr
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Inspection of Sediment Controls The
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12.1 Introduction As Fayette County
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12.2 Dry Detention Pond 12.2.1 Desc
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12.3 Dry Extended Detention Pond 12
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12.4 Wet Detention Pond 12.4.1 Desc
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12.5 Constructed Wetlands 12.5.1 De
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12.6 Biofiltration Practices 12.6.1
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12.7 Infiltration Practices 12.7.1
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12.8 Modular Pavement 12.8.1 Descri
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12.10 Prefabricated Treatment Devic
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1Lexington-Fayette Urban County Gov
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2Infiltration Basin Maintenance Ins
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3Infiltration Swale Maintenance Ins
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Action to be taken: If any of the a
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6Filtration Facility Maintenance In
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Summary of Changes to the LFUCG Sto
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11.5.5 Storm Drain Inlet Protection
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Stormwater Manual - Pima County Flood Control District

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