1、 CHAPTER 9 STORM DRAIN SYSTEMS 2007 by the American Association of State Highway and Transportation Officials. 2007 by the American Association of State Highway and Transportation Officials.CHAPTER 9 TABLE OF CONTENTS 9.1 INTRODUCTION. 9-1 9.2 PLANNING AND COORDINATION 9-2 9.2.1 Drainage Involvement
2、 by Others . 9-2 9.2.2 Cooperative Projects 9-3 9.3 DRAINAGE DATA 9-3 9.3.1 Sources of Drainage Data 9-3 9.3.2 Types of Drainage Data . 9-4 9.4 HYDROLOGY 9-5 9.4.1 Calibration of Computations 9-5 9.4.1.1 Hydrologic Calibration. 9-5 9.4.1.2 Hydraulic Calibration. 9-5 9.5 ELEMENTS OF SYSTEM DESIGN 9-6
3、 9.5.1 Pavement Drainage 9-6 9.5.1.1 Curb and Gutter Flow. 9-6 9.5.1.2 Surface Drainage of Pavements . 9-8 9.5.1.2.1 Pavement Texture 9-8 9.5.1.2.2 Mechanics of Flow on Pavements . 9-9 9.5.1.2.3 Ruts and Puddles . 9-12 9.5.1.3 Inlets. 9-12 9.5.1.3.1 Inlet Location. 9-12 9.5.1.3.2 Inlet Size 9-14 9.5
4、.1.3.3 Grate Inlets 9-14 9.5.1.3.4 Curb-Opening Inlets 9-17 9.5.1.3.5 Slotted Drain Inlets 9-18 9.5.1.3.6 Combination Inlets 9-19 9.5.1.3.7 Bridge Deck Inlets . 9-20 9.5.1.4 Design Criteria . 9-21 9.5.1.4.1 Flood Frequency 9-22 9.5.1.4.2 Allowable Water Spread 9-23 9.5.1.4.3 Surface Water Depth 9-24
5、 9.5.2 Storm Drains 9-24 9.5.2.1 Hydraulics of Storm Drains 9-25 9.5.2.1.1 Open-Channel vs. Pressure Flow. 9-25 9.5.2.1.2 Storm Drain Outfalls 9-27 9.5.2.1.3 Head Losses in Storm Drains 9-28 9.5.2.1.4 Hydraulic Gradeline 9-29 2007 by the American Association of State Highway and Transportation Offic
6、ials.Highway Drainage Guidelines 9-iv 9.5.2.2 Storm Drain Design Criteria .9-30 9.5.2.2.1 Flood Frequency.9-31 9.5.2.2.2 Maximum Highwater .9-32 9.5.2.2.3 Minimum Velocities.9-32 9.5.2.3 Design Process and System Planning .9-32 9.5.2.4 Appurtenant Structures .9-34 9.5.2.4.1 Access Holes 9-34 9.5.2.4
7、.2 Junction Chambers .9-36 9.5.3 Roadside Channels .9-37 9.5.4 Storage Facilities 9-37 9.5.4.1 Types of Facilities.9-38 9.5.4.1.1 Detention Facilities 9-39 9.5.4.1.2 Retention Facilities.9-41 9.5.4.1.3 Recharge Facilities .9-42 9.5.4.2 Inflow and Outflow Structures9-42 9.5.4.3 Safety 9-43 9.5.5 Stor
8、mwater Pumping Stations 9-44 9.5.5.1 General Considerations.9-44 9.5.5.2 Location 9-44 9.5.5.3 Hydrology .9-45 9.5.5.4 Storm Drain Collection Systems.9-46 9.5.5.5 Types of Stations 9-46 9.5.5.6 Station Design.9-47 9.5.5.6.1 Number and Capacity of Pumps.9-47 9.5.5.6.2 Sump Pump 9-48 9.5.5.6.3 Types o
9、f Pumps9-48 9.5.5.6.4 Types of Power 9-48 9.5.5.6.5 Sump Design 9-50 9.5.5.6.6 Pump On-Off Settings9-50 9.5.5.6.7 Pump Controls9-51 9.5.5.6.8 Discharge Piping 9-51 9.5.5.6.9 Flap Gates and Check Valves.9-51 9.5.5.6.10 Roof Hatches and Monorails9-51 9.5.5.6.11 Trash Racks and Grit Chambers.9-52 9.5.5
10、.6.12 Ventilation9-52 9.5.5.6.13 Telemetering 9-52 9.5.5.7 Specifications9-52 9.5.5.8 Equipment Certification and Testing 9-52 9.5.5.9 Construction9-53 9.5.5.10 Maintenance9-53 9.5.5.11 Retrofitting Existing Stations9-53 9.5.5.12 Architectural Considerations 9-53 9.5.5.13 Total Annual Cost.9-54 9.5.
11、5.14 Safety 9-54 9.5.5.15 Reliability .9-54 2007 by the American Association of State Highway and Transportation Officials.Storm Drain Systems 9-v9.5.6 Outfalls. 9-54 9.5.6.1 General Outfall Considerations 9-55 9.5.6.2 Design and Analysis of Outfalls. 9-57 9.5.6.2.1 Hydrology 9-57 9.5.6.2.2 Hydrauli
12、cs 9-58 9.5.7 Siphons. 9-59 9.5.7.1 Systems for Draining Subsurface Water 9-60 9.5.7.2 Horizontal Drains . 9-62 9.5.7.3 Pipe Underdrains 9-63 9.5.7.4 Vertical Wells. 9-65 9.5.7.5 Subgrade Drainage Systems. 9-66 9.5.7.6 Edge Drain Collector Systems . 9-67 9.6 FACTORS AFFECTING DESIGN. 9-68 9.6.1 Util
13、ities. 9-68 9.6.2 Easements 9-70 9.6.3 Service Life of Drainage Pipe 9-71 9.6.4 Erosion, Sedimentation, and Water Quality. 9-74 9.6.5 Attractive Nuisance Mitigations 9-74 9.6.6 Legal Factors 9-75 9.7 COMPUTER MODELS. 9-76 9.7.1 General Features 9-76 9.7.2 Hydrology 9-77 9.7.2.1 Peak Discharge Determ
14、ination. 9-77 9.7.2.2 Surface Hydrologic Simulation 9-78 9.7.3 Storm Drain Inlets 9-78 9.7.4 Underground Appurtenances . 9-79 9.7.4.1 Conduit Systems. 9-79 9.7.4.1.1 Hydraulic Gradeline 9-79 9.7.4.1.2 Supercritical Flow 9-80 9.7.4.2 Other Losses. 9-80 9.7.5 Water Quality. 9-80 9.7.6 Cost Estimating
15、9-80 9.8 DOCUMENTATION 9-81 9.9 CONSTRUCTION 9-82 9.9.1 Construction-Related Hydraulic Considerations . 9-82 9.9.2 Hydraulic-Related Construction Considerations . 9-85 9.10 MAINTENANCE 9-86 9.10.1 Maintenance-Related Hydraulic Considerations . 9-86 9.10.2 Hydraulic-Related Maintenance Considerations
16、 . 9-87 9.10.2.1 Maintenance Inspections 9-87 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 9-vi 9.10.2.2 Performance Evaluation9-87 9.11 REFERENCES 9-87 2007 by the American Association of State Highway and Transportation Officials.Chapte
17、r 9 Storm Drain Systems 9.1 INTRODUCTION The highway facility should be designed to be compatible with existing drainage patterns. Concurrently, the highway and the traveling public should be protected from the hazards of flooding. In this regard, the drainage design for the highway facility has a t
18、hreefold purpose: prevent adverse interference to the existing drainage, protect the traveled roadway surface from certain flood events, and provide for the removal of water from the roadway subgrade and the embankment. Storm drain system design should recognize that floodwater reaches the highway r
19、ight-of-way in three main ways: precipitation falling within the right-of-way; stormwater that flows onto the right-of-way as surface or overland flow; stormwater that comes to the highway in a defined watercourse. Water in a defined watercourse is usually conveyed as cross-drainage. In such cases,
20、a primary design objective is to pass stormwater through the highway embankment without adverse effects to the highway or to the property on either side. Guidance for the design of cross-drainage facilities is contained in Chapters 4 and 7 (4, 7)1and HDS 5 (39). Although stormwater approaching the h
21、ighway in a defined watercourse may be accommodated in a storm drain system, the primary concern of this chapter is floodwater from rain falling within the right-of-way and from overland flow. Guidance is given on how storm drain systems can be designed to collect, convey and discharge stormwater fl
22、owing within and along the highway right-of-way. This chapter covers most types of highway drainage excluding cross-drainage as defined above and most types of highway drainage facilities excluding culverts and bridges. Storm drain systems include elements such as: pavement drainage, inlets, 1Number
23、s in parentheses refer to publications in “References” (Section 9.11). 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 9-2 storm drains, roadside drainage channels, stormwater storage facilities, systems for draining subsurface water, siphon
24、s, pumping stations, outfalls, water quality facilities, and hazardous spill containment systems. In addition to discussion on the design of these elements, this chapter also discusses various factors affecting storm drain system design, computer modeling of storm drains, documentation and considera
25、tions pertaining to construction and maintenance. Serious consideration and application of the subjects discussed in this chapter can have a positive effect on the efficiency, safety and cost of highway storm drain facilities. 9.2 PLANNING AND COORDINATION Planning and coordination of storm drain sy
26、stems should begin in the early planning phase of a project with an examination of existing drainage patterns and the potential impact of the proposed highway facility. As highways cross rivers, streams, and watersheds, in general, there can be impacts on the existing drainage patterns and the local
27、 environment that may involve all levels of government agencies. Prior to the design of storm drain systems, it is essential to coordinate with the agencies that have interests in drainage matters. Such agencies could include municipalities that desire to utilize portions of the storm drain system t
28、o provide for new or better drainage and to augment old municipal drainage systems. Concerns of these agencies could include the highways interruption of existing drainage patterns, a concentration of flow by the highway system and possible detrimental discharge at higher velocities and rates into e
29、xisting downstream channels or storm drains. Also important are the concerns of citizens who fear that the drainage facility might impact their business or home and of developers who are planning major developments in the vicinity of the road project. The effects of development may be a controlling
30、factor in the design of roadway drainage. Close communication with local agencies and citizens can help the designer in providing a highway drainage system that will benefit the highway user and the local citizens. 9.2.1 Drainage Involvement by Others The design of highway storm drain systems will u
31、sually involve or affect local entities, developers and citizens owning property along the highway. These groups may wish to improve or change the land use, redirect the stormwater onto the right-of-way or propose joint projects that could require the highway storm drain system to carry water for wh
32、ich it would not usually be designed. Local 2007 by the American Association of State Highway and Transportation Officials.Storm Drain Systems 9-3ordinances often restrict or prohibit runoff rates in excess of those that existed prior to the highway location or improvement, or there may be more rest
33、rictive criteria than those normally used in design. Agricultural and industrial operations can change landscape and ground cover that may affect the magnitude and frequency of stormwater entering the roadway drainage system. Planning and coordination is accomplished through early disclosure and con
34、tact with local agencies, entities, local citizens in the public hearing processes and office communications. A well-designed, new or improved highway drainage system can alleviate a chronic drainage problem, whereas other local drainage problems could be resolved by allowing the municipality to tak
35、e advantage of the proposed highway drainage system. 9.2.2 Cooperative Projects Some cooperative projects can be included during the hydraulic design of the storm drain system without increasing highway costs. However, some projects commonly involving storm drains, pumping stations, and storage faci
36、lities may cause significant increases in the cost of highway improvements. These projects often require an agreement covering design, construction, maintenance, cost-sharing, and liability. If an agreement is necessary, it should be made only with other governmental agencies. If other parties (e.g.
37、, land owners, developers, corporations) are involved, their responsibilities and liabilities should be borne by a cognizant governmental agency so that the perpetuity of the agreement will be guaranteed. The nongovernmental participant would be involved in the project as deemed appropriate by their
38、 cognizant governmental agency. 9.3 DRAINAGE DATA Complete and accurate drainage data is essential to the design of any storm drain system. The hydraulic designer should obtain data that is commensurate with the risks, costs and complexity of the proposed storm drain facility. This section of the ch
39、apter discusses the sources and types of drainage data. 9.3.1 Sources of Drainage Data Although not all-inclusive, the following identifies the common sources of drainage data: field surveys; aerial photography (controlled and non-controlled); planning agencies; local master drainage plans; utility
40、companies; newspapers and news personnel; residents that can provide information on flood history; U.S. Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS); U.S. Geological Survey (USGS); USGS Quadrangle Maps; 2007 by the American Association of State Highway and Transpor
41、tation Officials.Highway Drainage Guidelines 9-4 city and county personnel; highway agency files; highway design and maintenance personnel; previous or ongoing drainage studies by other agencies; U.S. Army Corps of Engineers (USACE); Federal Emergency Management Agency (FEMA); National Oceanic and A
42、tmospheric Administration (NOAA); river authorities; drainage districts; agencies responsible for the operation of a reservoir; State or local mapping agencies; and Federal or State environmental agencies. 9.3.2 Types of Drainage Data The following is a list of some types of data that might be neede
43、d: watershed boundaries and sizes; existing drainage patterns; complete description of potential outfall locations; general description of ground cover; land use (present and expected future); flood histories and highwater mark elevations; age and description of existing drainage facilities (size, s
44、hape, material, invert elev., condition); design data of existing drainage systems; existing right-of-way; performance histories of existing facilities; utility locations (plan and elevation) and descriptions; soil conditions; local ordinances; FEMA requirements (National Flood Insurance Program); l
45、ocal governments desire to participate; U.S. Environmental Protection Agency (U.S. EPA) requirements for National Pollutant Discharge Elimination System; topographic data; and highway geometric data (pavement cross slope, pavement width, longitudinal gutter grade, etc.). 2007 by the American Associa
46、tion of State Highway and Transportation Officials.Storm Drain Systems 9-59.4 HYDROLOGY The system design is dependent on an estimate of magnitude, volume, and distribution of storm runoff. An overestimate of storm runoff can result in an excessive expenditure of construction funds. An underestimate
47、 may result in storm-related damages and traffic interruption due to the poor performance of an inadequate system. There are numerous techniques for making stormwater runoff estimates. Some of these techniques estimate only an instantaneous peak flow rate while others also yield a hydrograph, thereb
48、y providing an estimate of runoff volume and distribution. The momentary peak flow rate estimates are most often used in the design of roadside channels, cross drain culverts and storm drain systems. Drainage systems employing pumping stations, detention, retention or recharge basins and large, complex storm drain systems require the use of hydrographs. The technique used should be commensurate with the cost, risk and importance of the system. A discussion of various hydrologic techniques is contained in Chapter 2 (2) and HDS 2 (37). 9.4.1 Calibration of Computations Fo
