1、 CHAPTER 10 EVALUATING HIGHWAY EFFECTS ON SURFACE WATER ENVIRONMENTS 2007 by the American Association of State Highway and Transportation Officials. 2007 by the American Association of State Highway and Transportation Officials.CHAPTER 10 TABLE OF CONTENTS 10.1 INTRODUCTION. 10-1 10.1.1 Purpose of t
2、he Chapter 10-2 10.1.2 Role of the Hydraulics Engineer. 10-2 10.1.3 Environmentally Sensitive Surface Water Environments. 10-4 10.1.4 Surface Water Effect and Significance . 10-4 10.1.5 Threshold Value 10-5 10.1.6 Reversible and Irreversible Effects. 10-5 10.1.7 Legal Constraints 10-5 10.1.8 Organiz
3、ation of the Chapter 10-6 10.1.9 Survey and Data Collection 10-7 10.1.10 Implementing Environmental Plans 10-7 10.2 ESTIMATING SURFACE WATER EFFECTS 10-7 10.2.1 Quantity Effects 10-7 10.2.1.1 Surface Water Inventory 10-8 10.2.1.2 Floodplain Inventory 10-10 10.2.1.3 Runoff Peaks and Volumes 10-10 10.
4、2.2 Quality Effects 10-16 10.2.2.1 Sediment . 10-16 10.2.2.1.1 Sediment Transport 10-16 10.2.2.1.2 Sediment Data 10-17 10.2.2.1.3 Estimating Existing Sediment Regimes. 10-18 10.2.2.1.4 Construction Erosion . 10-19 10.2.2.1.5 Sediment Effects 10-21 10.2.2.1.6 Significance of Sediment Effects. 10-26 1
5、0.2.2.2 Mineral and Chemical. 10-26 10.2.2.3 Character and Aesthetics. 10-35 10.2.2.3.1 Character 10-35 10.2.2.3.2 Aesthetics. 10-35 10.2.3 Climatological Effects 10-36 10.2.3.1 Data. 10-36 10.2.3.2 Temperature 10-37 10.2.3.3 Season Delimitation 10-38 10.2.3.4 Precipitation 10-38 10.2.4 Biological E
6、ffects 10-40 10.2.5 Socioeconomic Effects 10-41 10.3 MITIGATING SURFACE WATER EFFECTS 10-41 10.3.1 Quantity Effects 10-42 10.3.1.1 Surface Water Inventory . 10-43 10.3.1.2 Floodplains 10-43 10.3.1.3 Runoff Peaks and Volumes. 10-44 2007 by the American Association of State Highway and Transportation
7、Officials.Highway Drainage Guidelines 10-iv 10.3.2 Quality Effects.10-47 10.3.2.1 Erosion and Sediment.10-47 10.3.2.2 Mineral and Chemical 10-47 10.3.2.3 Character and Aesthetics 10-51 10.3.3 Climatological Effects .10-51 10.4 STREAM MODIFICATION AND MITIGATIVE PRACTICES10-51 10.4.1 Need for Mitigat
8、ive Practices10-51 10.4.2 Design Discharge for Fish Migration 10-52 10.4.3 Fish Passage through Highway Structures 10-54 10.4.3.1 Fish Migrations10-55 10.4.3.2 Swimming Capability of Fish10-56 10.4.3.3 Types of Stream Fisheries .10-58 10.4.3.3.1 Tributary Streams to Large Lakes and Rivers10-58 10.4.
9、3.3.2 Steep Mountain Streams.10-58 10.4.3.3.3 Intermittent Streams .10-58 10.4.3.3.4 Groundwater Streams.10-58 10.4.3.3.5 Estuarine Streams.10-59 10.4.3.4 Data Collection for Stream Modifications.10-59 10.4.3.5 Fish Passage Design 10-60 10.4.3.5.1 Flow Depths .10-61 10.4.3.5.2 Structures with Natura
10、l Substrate Bottoms 10-63 10.4.3.5.3 Baffled and Sill Structures .10-65 10.4.3.5.4 Slot Orifice Structures10-67 10.4.4 Mitigating Channel Modification Effects10-68 10.4.4.1 Amount of Habitat.10-69 10.4.4.2 Quality of Habitat10-69 10.4.4.2.1 Geomorphology10-70 10.4.4.2.2 Pool and Riffle Sequence .10-
11、72 10.4.4.2.3 Substrate.10-74 10.4.4.2.4 Stream and Bank Cover10-75 10.4.4.2.5 Minimum Flow Requirements .10-78 10.4.4.2.6 Riparian Vegetation10-78 10.4.4.2.7 Water Quality .10-79 10.4.4.2.8 Construction Coordination .10-80 10.5 LAKE AND POND MODIFICATIONS AND MITIGATING PRACTICES .10-80 10.5.1 Feat
12、ures .10-80 10.5.2 Ecosystems 10-81 10.5.3 Water Characteristics.10-82 10.5.4 Classifications10-83 10.5.4.1 Source.10-84 10.5.4.2 Physical 10-84 10.5.4.3 Size .10-85 10.5.4.4 Productivity 10-85 10.5.5 Reservoir-Related Problems10-86 2007 by the American Association of State Highway and Transportatio
13、n Officials.Evaluating Highway Effects on Surface Water Environments 10-v10.5.6 Sedimentation . 10-87 10.5.7 Nutrient Enrichment 10-88 10.5.8 Other Pollutants 10-89 10.5.9 Circulation. 10-90 10.5.10 Sensitivity . 10-90 10.5.11 Evaluating Effects. 10-91 10.5.12 Data Collection for Lakes and Ponds 10-
14、93 10.5.13 Mitigating Measures . 10-94 10.5.13.1 Migration Routes 10-94 10.5.13.2 Lake Size. 10-95 10.5.13.3 Littoral Zone Substrate . 10-95 10.5.13.4 Diversion. 10-96 10.5.14 Ponds. 10-96 10.6 WETLANDS MODIFICATIONS AND MITIGATING PRACTICES. 10-96 10.6.1 Introduction. 10-96 10.6.1.1 Function of Wet
15、lands 10-98 10.6.1.2 Regulatory Requirements for Wetlands Considerations. 10-98 10.6.2 Classification of Wetlands 10-100 10.6.3 Wetlands Hydrology . 10-103 10.6.4 Potential Highway Effects to Wetlands 10-103 10.6.4.1 Water Depth 10-103 10.6.4.2 Seasonal Patterns 10-104 10.6.4.3 Erosion and Sedimenta
16、tion . 10-105 10.6.4.4 Suspended Solid Concentration 10-105 10.6.4.5 Chemical Regime 10-106 10.6.4.6 Dissolved Oxygen (DO) Regime 10-107 10.6.4.7 Nutrient Loading. 10-107 10.6.4.8 Pollutants 10-108 10.6.5 Estimating Highway Effects on Wetlands 10-109 10.6.5.1 Baseline Data 10-109 10.6.5.2 Highway Lo
17、cation. 10-110 10.6.5.3 Water Quality 10-110 10.6.5.4 Wetlands Hydrology . 10-111 10.6.5.5 Evaluation of Mitigation Alternatives. 10-111 10.6.6 Mitigation Measures . 10-112 10.6.6.1 Location 10-112 10.6.6.2 Tidal Wetlands Crossings . 10-113 10.6.6.3 Inland Wetlands Crossing Hydraulics. 10-115 10.6.6
18、.4 Erosion and Sedimentation . 10-117 10.6.6.5 Migration of Aquatic Biota. 10-117 10.6.6.6 Constructing New Habitat. 10-117 10.6.6.7 Compensation . 10-119 10.6.7 Wetlands Banking. 10-119 10.7 SURVEYS AND DATA COLLECTION 10-120 2007 by the American Association of State Highway and Transportation Offi
19、cials.Highway Drainage Guidelines 10-vi 10.7.1 Determining the Need10-121 10.7.1.1 Project Nature10-121 10.7.1.2 Public Input .10-121 10.7.1.3 Development by Others.10-122 10.7.2 Level of Effort .10-122 10.7.3 Office Survey and Data Collection10-122 10.7.3.1 Data Availability .10-122 10.7.3.2 Prelim
20、inary Environmental Estimates.10-124 10.7.4 Limited Field Studies 10-124 10.7.5 Complete Field Studies10-125 10.7.5.1 Determining General Objectives .10-125 10.7.5.2 Selecting Study Parameters .10-126 10.7.5.3 Selecting Sampling Sites .10-126 10.7.5.4 Temporal Sample Distribution 10-127 10.7.5.5 Sam
21、pling Frequency10-127 10.7.6 Study Level10-127 10.7.6.1 Planning Level.10-127 10.7.6.2 Project Level10-128 10.7.6.3 Construction Level 10-129 10.8 REFERENCES 10-129 2007 by the American Association of State Highway and Transportation Officials.Chapter 10 Evaluating Highway Effects on Surface Water E
22、nvironments 10.1 INTRODUCTION Highway engineers historically have recognized the need to provide drainage facilities that are in harmony with the surface water environment. In this chapter, surface waters are considered to be all open water such as streams, rivers, ponds, lakes, reservoirs, and wetl
23、ands. Their attendant environments are active functioning floodplains and/or contiguous riparian areas. Generally, engineering drainage design practices that protect the environment also protect the highway. Public emphasis and research directed at environmental quality continues to improve these en
24、gineering practices making the preparation of a state-of-the-art guide most difficult. The reader is therefore cautioned that some of the technology, guidelines, and regulatory guidance contained in this chapter may soon be, if they are not already, outdated. This chapter supports an environmental t
25、eam approach in evaluating the effects of highway construction and operation on surface waters, but ultimately the highway agencys hydraulics engineer must be in agreement with the final recommendation. Thus, this chapter must also alert the other environmental disciplines to the services that can b
26、e provided by the highway hydraulics engineer. The focus, however, is primarily to aid the hydraulics engineer with a hydrologic and hydraulic background in applying this knowledge towards assisting the highway agencys environmental team in evaluating surface water effects. For this reason, it is ne
27、cessary that the introduction define the role of the hydraulics engineer in this team effort. This introduction also presents to the reader the purposes and some of the less familiar terms that are used frequently throughout this chapter, such as: surface water environment, effects and their signifi
28、cance, reversible and irreversible effects, and threshold values. These terms are discussed in detail later in this chapter. 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 10-2 10.1.1 Purpose of the Chapter The principal purpose of this cha
29、pter is to provide general information for use in environmental statements and to provide specific guidance to aid the hydraulics engineer in preparing detailed analyses where such analyses are warranted or required. Other purposes of this chapter are to develop a common level of understanding to fa
30、cilitate communication between the hydraulics engineer and the other environmental disciplines and to provide a source of potentially useful technical practices. To satisfy these purposes requires the inclusion of an extensive list of references. Judgment and experience will indicate when it is nece
31、ssary to employ any of the guidelines in this chapter. It is not intended that all the guidelines presented in this chapter be routinely employed where there are environmental concerns. In reality, few (if any) of these guidelines will be required on most highway projects, and then only a few may be
32、 needed. These need to be identified on a case-by-case basis. To be effective, however, these guidelines need to be considered in the early stages of a project to avoid serious environmental problems that might otherwise have been avoided. The guidelines, background information, and references in th
33、is chapter are intended to: provide general information for use in environmental statements; flag those surface water locations that are of environmental concern; provide guidelines and references for evaluating any flagged locations; suggest design practices to mitigate expected environmental damag
34、e; establish a common level of knowledge to facilitate communication between the environmental team members; and provide guidance on the conduct of field surveys. 10.1.2 Role of the Hydraulics Engineer The hydraulics engineer is a key individual on any interdisciplinary team that studies the relatio
35、nship of highways to surface waters. Other team members such as biologists, ecologists, and geologists rely on the hydraulics engineer for expertise in: analyzing hydrologic data, identifying practicable highway alternatives, forecasting effects and their significance, and devising mitigation measur
36、es. Successful incorporation of the hydrologic and hydraulic parameters into the project design to avoid delays in project implementation requires early integration of technical information into the planning process. This team approach helps to minimize project development time through early identif
37、ication of needed mitigative measures. The role of the hydraulics engineer may be thought of as fourfold: Quantify the existing hydrologic and hydraulic conditions before the proposed project is constructed using the guidelines and cited references, that is, establish surface water baseline conditio
38、ns against which impacts may be compared. Explain the constraints of the construction techniques to the other team members. 2007 by the American Association of State Highway and Transportation Officials.Evaluating Highway Effects on Surface Water Environments 10-3 Employ computer models to evaluate
39、the change of the hydrologic and hydraulic conditions caused by the proposed project. Evaluate the effects of this change on the surrounding environment. Design a drainage system that incorporates the needs of the biologists, ecologists, and other team members in mitigating adverse project effects w
40、hile operating within the constraints of time and money. The hydraulics engineer should also concisely document the findings of the study area. To facilitate communication with the environmental team, reports should contain all text, tables, figures, exhibits, photographs, charts, appendices, and bi
41、bliographies with a minimum of technical jargon; the report should focus on matters relevant to the issues and quickly dispel non-relevant items raised by others. The level of data presentation and analysis should be commensurate with the relative importance of the issue. Discussions of less importa
42、nt parameters are better summarized, consolidated, or simply referenced. Highway hydraulics engineers, because of their technical background in highway design and construction, have a key role to play as intermediaries between the physical, biological, and cultural team members and other highway eng
43、ineers. In this role, the experienced hydraulics engineer will be most useful as he can save the highway agency both time and money by defusing potential conflicts between individuals and agencies. There are times when an individual outside the highway engineering science will have a limited concept
44、ion of the engineering and monetary constraints associated with the construction of a highway. Such individuals may be unable to identify practicable limits for the protection of surface waters. Hopefully, protection can be a compromise where necessary cost-effective mitigation measures are incorpor
45、ated into the project design to eliminate or reduce to an acceptable level long-term or permanent adverse effects. Realistically, it must be recognized that resource and regulatory agencies will emphasize three basic alternatives regarding the disturbance of surface waters. These, in their order of
46、priority, are: avoidance, minimization, and mitigation. The hydraulics engineer also has a role in identifying the direct and indirect effects (as explained later) of the proposed action on the hydrologic and hydraulic regime of surface waters and discussing their significance. The complexity of the
47、 hydrologic and hydraulic regime of wetland surface waters makes involvement of the hydraulics engineer essential when these issues are raised. Projections regarding these issues should, to the extent practicable, be specific and quantified. Important to such projections may be a baseline data colle
48、ction program. Complete baseline data coupled with the hydraulics engineers technology will furnish results that are useful to other team members. Finally, the hydraulics engineer can work with other highway disciplines to devise and construct mitigation measures that reduce adverse effects. The hyd
49、raulics engineer can provide the following services: recommend optimum locations, geometries, and sizes for hydraulic facilities such as culverts, bridges, and channels; identify spoil disposal areas; 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 10-4 devise methods to reduce sedimentation and er
