Stormwater Manual - Pima County Flood Control District

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A = surface area of filter = width of sand layer * length of sand layer (ft 2 ), t = time (hr), H = height of water over the perforated pipe with full extended detention pool (ft), and h = height of filter from the top of the perforated pipe to the top of the sand (ft). Size the sand filter trenches relative to the underdrain pipe such that the sand filter controls the discharge rate rather than the drain pipe. Provide calculations demonstrating that the underdrain pipe will convey the design flow rate under gravity flow conditions. 10.8.4 Specifications Specifications are consistent with those provided in section 10.7. STORMWATER MANUAL 10-30 January 1, 2009 LEXINGTON-FAYETTE CO., KY.
10.9 Wet Ponds In this manual, wet pond refers to a basin designed for both water quality and water quantity management and which has a permanent pool. Figure 10-14 illustrates a wet pond. 10.9.1 Applicability Wet ponds can be used for water quantity management and water quality treatment. For water quality treatment, the WQV is at least equal to the WQV derived from Table 10-1, less any credits earned from bioretention and infiltration. Design ponds to be placed outside the receiving stream except when a pond is designed as a regional detention pond. 10.9.2 Design Criteria Design retention ponds to have a contributing drainage area of at least 10 acres and a surface area of at least one-fourth of an acre. When using a wet pond with a permanent pool for water quality control, size the permanent pool to at least equal the design WQV. To calculate the design WQV, take the full WQV for the site, minus any credits allowed for infiltration and bioretention. Design the permanent pool to have an average depth between 3 feet and 6 feet and a maximum depth of no more than 8 feet. Design wet ponds to be wedge-shaped with the narrow end at the inlet and the wide end at the embankment. Provide a minimum length to width ratio of 3:1 or provide gabion baffles to extend the flow path to a length that meets or exceeds the path that would be achieved using a 3:1 length to width ratio. Provide irregular shorelines so that the permanent pool has a natural appearance. Provide a 10-foot wide, 12-inch deep, underwater bench around the perimeter except at the embankment. Provide safety benches at least 10 feet wide around the perimeter above the permanent pool. Design these benches to have a slope not greater than 10:1 (h:v). Design a liner for the permanent pool using on-site soils or other materials. Document that the proposed soils are suitable for use as a liner by providing soil classification data (Unified STORMWATER MANUAL 10-31 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
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4.4 Record Drawings A record drawin
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5.1 Introduction 5.1.1 Purpose The
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5.3 Design Rainfall Event 5.3.1 Sin
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TABLE 5- 2 GREEN-AMPT INFILTRATION
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5.5 Stormwater Management Model (SW
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TABLE 5- 4 MANNINGS N FOR OVERLAND
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APPENDIX 5 A DESIGN STORM DISTRIBUT
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6-HOUR RAINFALL DISTRIBUTIONS Cumul
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100-YEAR - 24-HOUR RAINFALL DISTRIB
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CHAPTER 6 INLETS / STORM SEWERS / M
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6.1.4 Storm Sewers Storm sewers sha
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For d ≥ 1.0’, use the orifice f
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6.4 Construction Specifications All
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7.1 Introduction As used in this ma
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7.2.6 Culvert Skew A culvert shall
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Barrel Area and Shape Barrel area i
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7.5 Bridge Design Procedures Use HE
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CHAPTER 8 CONSTRUCTED CHANNELS
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8.2 Permanent Constructed Channels
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The earth fill materials used to co
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8.3 Paved Channels A paved channel
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9.1 Introduction The streams of Fay
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9.2.3 Material Specifications Veget
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TABLE 9- 1 SUGGESTED RIPARIAN SPECI
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9.3 Riparian Buffer Zones 9.3.1 Gen
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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: Embankment heights shall not exceed
Page 161 and 162: Q = A (2gH) 0.5 /(1 + K e +K b + K
Page 163 and 164: Provide a drain with a valve at the
Page 180 and 181: CHAPTER 11 EROSION AND SEDIMENT CON
Page 182 and 183: 11.1 Purpose This chapter describes
Page 184 and 185: 1. The limitations on coverage set
Page 186 and 187: 11.2.2 Non-Structural Practices Thi
Page 188 and 189: Figure 11-1. “Seed mats” may be
Page 190 and 191: peak discharges during construction
Page 192 and 193: Locations of proposed controls, uti
Page 194 and 195: 11.4 Structural Soil Stabilization
Page 196 and 197: When using a mulch net, it shall be
Page 198 and 199: Material Specifications Seed shall
Page 200 and 201: Material Specifications Soil materi
Page 202 and 203: 11.4.5 Road/Parking Stabilization R
Page 204 and 205: To reduce maintenance and loss of a
Page 206 and 207: 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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