1、April 2016ConstructionStormwaterField GuideCopyright 2016, Center for Environmental Excellence by AASHTO (American Association of State Highway and Transportation Officials). All Rights Reserved. This book, or parts thereof, may not be reproduced in any form without written permission of the publish
2、er. Printed in the United States of America.This material is based upon work supported by the Feder-al Highway Administration under Cooperative Agreement No. DTFH61-07-H-00019. Any opinions, findings, and con-clusions or recommendations expressed in this publication are those of the author(s) and do
3、 not necessarily reflect the view of the Federal Highway Administration.Table of ContentsChapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Chapter 2. Pollution Prevention and General Housekeeping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14M
4、aterial and Waste Management . . . . . . . . . . . . . . . . . 14Street Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Protection of Permanent BMPs . . . . . . . . . . . . . . . . . . . 27Illegal Discharges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28P
5、aving and Concrete Construction . . . . . . . . . . . . . . . . 30Non-Stormwater Management . . . . . . . . . . . . . . . . . . . 32Chapter 3. Sediment Control . . . . . . . . . . . . . . . . . . . . . . 34Perimeter Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Dewatering . .
6、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Sediment Traps and Basins . . . . . . . . . . . . . . . . . . . . . . . 49Chapter 4. Erosion Control . . . . . . . . . . . . . . . . . . . . . . . . . 52Surface Roughening . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Ta
7、ckifier and Binders . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Hydroseeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Mulching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Rolled Erosion Control Products . . . . . . . . . . . . .
8、. . . . . 63Chapter 5. Temporary Drainage Management . . . . . . . . . 68Stream Crossing and Bank Stabilization . . . . . . . . . . . . 68Temporary Berms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Storm Drain Inlet Controls . . . . . . . . . . . . . . . . . . . . . . . 78Slope Dra
9、ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Temporary Check Dams . . . . . . . . . . . . . . . . . . . . . . . . . 85Outlet Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10、. . . . . . . . 94Table of Contents | 1Ch. 1. Introduction | 2Chapter 1. INTRODUCTIONScope and ObjectiveConstruction sites can be a source of sediment and other pollutants to waterways . Best management practices (BMPs) are devices and activities that reduce or eliminate pollution sources and can in
11、clude silt fences, settling ba-sins, and even training .This guide is a quick reference for inspectors and resident engineers in construction on topics related to installation, maintenance, and inspection of common BMPs . Using this guide helps departments of transportation (DOTs) stay in compliance
12、 with federal, state, and local regulations for improving stormwater quality and provides guidance where local publications may currently be lacking .Fig. 1-1. Proper management of construction sites through the use of BMPs can dramatically reduce stormwater impacts. Source: RBF ConsultingPreface to
13、 ReadersThis publication includes discussion of BMPs, organized by their use . Categorization of BMPs may vary from state to state; however the basic recommendations for field implementation remain consistent . The information presented in this guide is based on techniques and control measures consi
14、dered generally effective in many areas of the country . This guide is not meant to be a design manual or pollution prevention plan, nor is it meant to supersede, substitute, or make more stringent well-defined practices or regulatory standards .Fig. 1-2. Construction sites should aim to produce no
15、more sediment risk than the natural condition as this re-vegetated slope does.Source: Utah DOTFederal Laws and RequirementsFederal water quality regulations require that construction sites disturbing one acre or more of land get coverage under a National Pollutant Discharge Elimination System (NPDES
16、) permit . Permits may be issued by the United States Environ-mental Protection Agency (EPA) or at the state level .The goal of the EPA is to prevent the construction site from causing or contributing to water pollution . Water pollution can result from most activities on a construction site if they
17、 are not correctly managed with BMPs .BMPs use the following strategies to protect water quality:I Reduce the time bare soil is exposed to rainfall by project sequencing and scheduling .Ch. 1. Introduction | 3I Use pollution prevention as a more practical and effective means compared to pollution re
18、moval . Do what is possible to prevent pollution contact with stormwater .I Use effective combinations of erosion and sediment control measures on the construction site . I Use buffers of natural vegetation when construction sites are next to environmentally sensitive areas or water bodies .I Contro
19、l the perimeter of the site with appropriate sediment controls .I Reduce the volume of construction site runoff wherev-er feasible .I Control offsite/onsite runoff during construction to protect slopes and disturbed areas .I Avoid disturbing natural channels .I Stabilize bare soil areas as soon as p
20、ossible, to elimi-nate erosion .The information discussed in this guide provides informa-tion on installing and maintaining BMPs so that they are effective .Erosion Control FundamentalsYou need an understanding of the different types of ero-sion to maintain erosion control BMPs .Splash erosion is th
21、e primary source of erosion . It results from rain drops striking bare soil directly . Sheet erosion is the removal of a uniform thin layer of soil by raindrop splash or water runoff . It is characterized by a surface film of water 1/16”1/8” deep .Rill erosion results from sheet flow that becomes co
22、ncen-trated into many small channels . Rill erosion areas are generally small enough to step across .Gully erosion is easily identifiable by large (too far to step across), deep cuts in the soil . They are often found in areas Ch. 1. Introduction | 4without evidence of other erosion types . Rill ero
23、sion can easily progress to gully erosion if BMPs are not installed, installed correctly, or not maintained .Fig. 1-3. Splash erosion is often very hard to see, but it is a significant physical process.Source: http:/www.dot.ca.gov (modified)Fig. 1-4. Gully formation occurs when flows are not adequat
24、ely controlled with the appropriate BMPs.Source: RBF ConsultingCh. 1. Introduction | 5Fig. 1-5. All forms of erosion can occur at a construction site. Here the rills and gullies will need repair and could have been prevented with proper BMPs. Source: RBF ConsultingGeneral TipsAssessment and Planning
25、You should perform a general site assessment and plan-ning before implementing BMPs . Things to be reviewed in the field include:I Review the projects stormwater pollution prevention plan (SWPPP) requirements .I Identify and understand the basic drainage patterns of the project sitefrom where does r
26、unoff originate, where does it go, and how much is anticipated . I Understand how the continuing sequence of project construction activities will change current drainage patterns based on grading, vegetation changes, pav-ing, and other physical features .I Identify all areas where runoff will discha
27、rge from the site for all phases of construction .I Identify the areas of the project site that are the most likely sources of sediment . Cover and contain construc-tion materials .Ch. 1. Introduction | 6I Select BMPs for runoff management, soil stabilization, and sediment control based on the proje
28、ct site condi-tions, geography, and typical precipitation patterns .BMP Tool BoxRunoff ManagementRunoff management approaches include tools to convey water into and through the site . In many instances, pru-dent runoff management strategies involve the diversion of clean water from offsite areas aro
29、und the site .Fig. 1-6. Planning flow chartrunoff management.BMP Tool BoxSoil StabilizationErosion control BMPs include a range of cover options including spray-on binders, spray-on mulches, spray-on ma-trices, hydroseed, rolled erosion control products (RECPs), and others . They all share common fu
30、nction in that they keep soil from becoming mobile . The best approach for your site will depend on the intended design life, project slope, soil type, environmental requirements, and cost . In general, the original product used for erosion control will need to be reapplied as it becomes ineffective
31、 over time .Ch. 1. Introduction | 7Fig. 1-7. Planning flow chartsoil stabilization.BMP Tool BoxSediment ControlSediment control BMPs include silt fence, wattles, gravel bags, check dams, and sediment basins and traps . These measures should always be used as a supplement to appro-priate runoff manag
32、ement and erosion control BMPs .Fig. 1-8. Planning flow chartsediment control.Ch. 1. Introduction | 8Controlling DustWind erosion control practices function by:I Reducing wind effects on the soil surface by covering piles with a wind-impervious fabric or other material, or by changing pile orientati
33、on and shape and/or;I Water or calcium chloride applications .Special Considerations for Linear Projects Linear projects such as highways present special challenges for installation and maintenance of BMPs . Safety con-siderations, along with limited work area for effectively managing erosion and se
34、diment controls are two main challenges . The following are things to keep in mind when maintaining BMPs for linear projects:I Avoid deep ponding areas that are not protected by temporary barriers . I Do not allow water to pond in the clear recovery zone .I Pay attention to sight distance obstructio
35、ns when se-lecting controls . Do not use controls that may obstruct sight lines .I Create a plan for maintenance . BMPs must be main-tained; provide access that does not require traffic control and keeps personnel safe .I Do not use inlet protection BMPs that would cause flooding in the traveled way
36、, or cause the flow spread to enter the traveled way .I Use alternative control methods where standing water may create potential hazards . I Large drainage areas present situations with high flow volumes but limited areas for proper controls . It is imperative to recognize these areas at the be-gin
37、ning of a project and identify BMPs intended to control large flows at the start and as construction progresses . And also: Look to provide diversions to bypass offsite water around the project area .Ch. 1. Introduction | 9 Use alternative BMPs or modify the traditional de-sign when limited work are
38、a is a concern .Communication During ConstructionDesignate a point of contact within all functional units as-sociated with a project regarding construction stormwater issues . Construction sites change over time . Make sure the site meets the requirements of the stormwater pollution prevention plan
39、(SWPPP) at all times . Keep good docu-mentation, and take pictures of BMPs before and after maintenance .Fig. 1-9. Covering a pile and maintaining a low profile shape are good ways to reduce wind erosion potential.Source: RBF ConsultingRecord Keeping and ReportingProject documents must be kept for a
40、t least three years from the date the site is stabilized and the NPDES coverage is terminated . At a minimum, records should include:I Copy of the project SWPPP and its amendments .I Permit application and termination records .I Inspection forms, including the date, place, time, significant observat
41、ions (spills, leaks, etc .), and all non-stormwater discharges .| 10Ch. 1. IntroductionI The corrective Action Log .I Records of weather conditions (keeping a rain gage on site is highly recommended) .I BMP maintenance activity and troubleshooting .I Names of inspector(s) and other key members of th
42、e DOT, contractor, and sub-contractors .Fig. 1-10. Establishing responsibility for regular inspection and maintenance of stormwater BMPs is an important part of work and communication management key to preventing failures as show here. Source: RBF ConsultingWork ManagementStormwater pollution preven
43、tion is typically handled by more than one person . Roles and responsibilities should be understood and documented within the project SWPPP including:I Overall leadI Spill responseI Weather monitoringI Housekeeping and BMP installation and maintenanceI Record keeping and reportingI TrainingCh. 1. In
44、troduction | 11General BMP Inspection and TroubleshootingEach BMP presented in this guide has information on inspection, maintenance, and associated work . Many of the problems occurring in the field fall into the following general categories and are not associated specifically with any one BMP . A
45、consideration for all is staff training .Table 1-1. General BMP TroubleshootingIf Your BMP ExperiencesThen ConsiderErosion Additional erosion control/soil stabilization BMPs Diversion of flow around the area of concern using temporary runoff management practices Modifying your construction sequence
46、or scheduleTurbid Discharge Maintenanceor redesignSediment and DebrisBuildup Additional erosion control/soil stabilization BMPs More frequent maintenanceand clean out Diversion using temporary runoff management practices Modifying your construction sequence or scheduleStanding Water Inspection of in
47、lets and pipes for blockage from trash and debris Limit thedrainagearea to the BMP using runoff management practices Increase the size (surface area) of your BMP Add erosion and sediment control BMPs within thecontributing drainage areaBypass Increase the size of your BMP Verify thesizeand physical
48、adequacy of inflow and outflow structures, conduits,etc.Malfunction Due toDesign Deficiency Providetemporary runoff management controls to divert runoff away from problem area Userunoff controls to slow the flow of runoff Contact the design engineer of record for solutionTrackout Perform maintenance
49、 or provide additional perimeter controls Verify that access points are controlled Providea tirecleaning area Perform street sweeping| 12Ch. 1. IntroductionFinal Stabilization and Permit TerminationBMPs must be maintained until work is completed, the project site is stabilized, and the project is eligible to end NPDES permit coverage . Requirements vary based on lo-cation, but stabilization generally occurs when vegetation covers unpaved areas with a uniform density of at least 70 percent of the pre-project condition . NPDES permit cover-age also requires:I
