FREE ELECTRONIC LIBRARY - Dissertations, online materials

Pages:   || 2 | 3 | 4 | 5 |

«CHAPTER 13 STORM DRAINS TABLE OF CONTENTS 13.1 OVERVIEW 13.1.1 Introduction 13.1.2 Symbols And Definitions 13.1.3 Concept Definitions 13.2 GENERAL ...»

-- [ Page 1 ] --

CDOT Drainage Design Manual Storm Drains





13.1.1 Introduction

13.1.2 Symbols And Definitions

13.1.3 Concept Definitions


13.2.1 Introduction

13.2.2 Hydrology

13.2.3 Design Frequency And Spread Width

13.2.4 Inlet Spacing


13.3.1 Introduction

13.3.2 Major Storm And Street Capacity

13.3.3 Longitudinal Slope

13.3.4 Cross Slope

13.3.5 Hydroplaning / Pavement Texture

13.3.6 Curb and Gutter

13.3.7 Concrete Median Barrier


13.4.1 General

13.4.2 Types

13.4.3 Inlet Criteria and Design

13.4.4 Inlet Capacities

13.4.5 Inlet Debris

13.4.6 Maintenance Access (Manhole) Locations

13.4.7 Maintenance Access Spacing

13.4.8 Curved Alignment


13.5.1 Introduction

13.5.2 Trunkline Criteria And Design

13.5.3 Trunkline Velocity

13.5.4 Hydraulic Design of Pipes

13.5.5 Special Considerations


13-1 CDOT Drainage Design Manual Storm Drains 13.6.1 Basic Data

13.6.2 Preliminary Design


13.7.1 Hydraulic Gradeline Procedure


13.9 Appendix A Design Nomographs

–  –  –

13.1 OVERVIEW 13.1.1 Introduction The primary aim of storm drain design is to limit the amount of water flowing along the gutters, or ponding at the sags, to quantities which will not interfere with the passage of traffic for a common design storm. The storm drain system consists of surface inlets structures connected to a underground pipe system. The inlets are located at points and at such intervals to intercept flows and control the water's spread width into the traveled lane.

Photo 13.1 Storm drain facilities should provide enough combined capacity in the storm drain and the street typical to convey the major storm runoff through the roadway right-of-way in a manner which adequately drains the roadway and minimizes the potential for flooding and erosion to properties adjacent to the right-of-way.

Storm drain design is one of the more cumbersome and difficult problems encountered in highway drainage. The complex network of inlets and conduits requires extensive evaluation to provide an efficient, balanced system.

Storm Drains should be designed by the CDOT Hydraulics Engineer or experienced drainage consultant.

Hydraulic design of projects contracted to consultants should be reviewed and approved by the CDOT Hydraulics Engineer.

The most serious effects of an inadequate roadway drainage system are:

• damaging adjacent property from the water overtopping the curb and gutter;

13-3 CDOT Drainage Design Manual Storm Drains

• risk and delays to the driving public caused by excessive ponding in sags or excessive spread along the roadway;

• deterioration of the pavement structure and subgrade due to saturation caused by frequent and long duration ponding; and

• creating hydroplaning conditions for motorists.

–  –  –

To provide consistency within this Chapter and throughout this Manual, the symbols in Table 13.1 will be used. These symbols were selected because of their wide use in storm drainage publications.

13.1.3 Concept Definitions Following are discussions of concepts that will be important in a storm drainage analysis and design.

These concepts will be used throughout the remainder of this Chapter in addressing different aspects of

storm drainage analysis:

Bypass Flow: Flow which bypasses an inlet on grade and is carried in the street or channel to the next inlet downgrade.

Check Storm: The use of a less frequent event (e.g., a 50-yr storm) to assess hazards at critical locations where water can pond to appreciable depths is commonly referred to as a check storm or check event.

Combination Inlet: A drainage inlet usually composed of a curb-opening inlet and a grate inlet.

Crown: The crown, sometimes known as the soffit, is the top inside of a pipe.

Culvert: A culvert is a closed conduit whose purpose is to convey surface water under a roadway, railroad or other impediment. It may have one or two inlets connected to it to convey drainage from the median area.

Curb-Opening: A drainage inlet consisting of an opening in the roadway curb. (ex. Type R inlet) Drop Inlet: A drainage inlet with a horizontal or nearly horizontal opening.

Equivalent Cross Slope: An imaginary straight cross slope having conveyance capacity equal to that of the given compound cross slope.

Flanking Inlets: Inlets placed upstream and on either side of an inlet at the low point in a sag vertical curve. These inlets intercept debris as the slope decreases and act in relief of the inlet at the low point.

Flow: Flow refers to a quantity of water that is flowing.

Frontal Flow: The portion of the flow that passes over the upstream side of a grate.

Grate Inlet: A drainage inlet composed of a grate in the roadway section or at the roadside in a low point, swale or channel. (ex. Type C or D inlet) Grate Perimeter: The sum of the lengths of all sides of a grate, except that any side adjacent to a curb is not considered a part of the perimeter in weir-flow computations.

Gutter: That portion of the roadway section adjacent to the curb which is utilized to convey storm water runoff. It may include a portion, or all, of a traveled lane, shoulder or parking lane, and a limited width, adjacent to the curb, may be of different materials and have a different cross slope.

Hydraulic Grade Line The hydraulic grade line is the locus of elevations to which the water would rise in successive piezometer tubes if the tubes were installed along a pipe run (pressure head plus elevation head).

Inlet Efficiency The ratio of flow intercepted by an inlet to total flow in the gutter.

Invert The invert is the inside bottom of the pipe.

Lateral Line A lateral line, sometimes referred to as a lead, has inlets connected to it but has no other storm drains connected. It is usually 2 ft or less in diameter and is tributary to the trunk line.

Lateral: The underground conduit that connects the inlet to the main trunkline of a storm drain.

13-5 CDOT Drainage Design Manual Storm Drains Major Storm: The 50 to 100-year runoff to be assessed for with a storm drain design for minimum ponding depth and property inundation.

Minor Storm: The common storm that is used for designing the inlet size and location, the trunkline size and the spread width.

Panline: The lowest point in the curb and gutter section.

Pressure Head: Pressure head is the height of a column of water that would exert a unit pressure equal to the pressure of the water.

Runby/Bypass: Carryover flow that bypasses an inlet on grade and is carried in the street or channel to the next inlet downgrade. Inlets can be designed to allow a certain amount of runby for one design storm and larger or smaller amounts for other storms.

Sag Point/Major Sag Point: A low point in a vertical curve. A major sag point refers to a low point that can overflow only if water can pond to a depth of 2 ft or more.

Scupper: A vertical hole through a bridge deck for deck drainage. Sometimes, a horizontal opening in the curb or barrier is called a scupper.

Side-Flow Interception: Flow that is intercepted along the side of a grate inlet, as opposed to frontal interception.

Slotted Drain Inlet: A drainage inlet composed of a continuous slot built into the top of a pipe that serves to intercept, collect and transport the flow. Two types in general use are the vertical riser and the vane type.

Storm Drain: A storm drain is a closed or open conduit that conveys stormwater that has been collected by inlets to an adequate outfall. It generally consists of laterals or leads and trunk lines or mains. Culverts connected to the storm drainage system are considered part of the system.

Splash-Over: Portion of frontal flow at a grate that skips or splashes over the grate and is not intercepted.

Spread: The width of stormwater flow in the gutter or roadway measured laterally from the roadway curb.

Trunk Line: A trunk line is the main storm drain line. Lateral lines may be connected at inlet structures or access holes. A trunk line is sometimes referred to as a “main.” Trunkline: The underground pipe portion of a storm drain system. Major conveyance element into which the smaller pipes or laterals drain into from the storm drain inlets.

Velocity Head: Velocity head is a quantity proportional to the kinetic energy of flowing water expressed as a height or head of water (V2/2g).

–  –  –

13.2 GENERAL DESIGN CRITERIA 13.2.1 Introduction Highway storm drainage facilities collect stormwater runoff and convey it through the roadway right-ofway in a manner that adequately drains the roadway and minimizes the potential for flooding and erosion to properties adjacent to the right-of-way. Storm drainage facilities consist of curbs, gutters, storm drains, channels and culverts. The placement and hydraulic capacities of storm drainage facilities should be designed to consider the potential for damage to adjacent property and to secure as low a degree of risk of traffic interruption by flooding as is consistent with the importance of the road, the design traffic service requirements and available funds.

Storm drain systems have two separate drainage systems. One is the minor drainage system to handle the ordinary recurring storm (2 to 10-year storm events). The other is the major system to handle the large infrequent storm flows (100-year storm event). The minor system consists of underground piping that is connected to inlets draining roadway or offsite areas. The major system includes street flow, urban storm channels and other overflow provisions to pass the infrequent, large flows without excessive ponding or property damage.

Following is a summary of policies that should be followed for storm drain design and analysis. For a general discussion of policies and guidelines for storm drainage, the designer is referred to Reference (1).

For more specific design and engineering guidance refer to the AASHTO "Drainage Manual", the Federal Highway Administration publication, HEC 21 and HEC 22. and the Denver Regional Council of Governments, "Urban Drainage and Flood Control District - Critenia Manual."

–  –  –

13.2.2 Hydrology The Rational Method is the suggested procedure to compute the peak flows for storm drain systems with drainage areas less than 160 acres. It is the method that applies to the vast majority of small watersheds that are to be handled by storm drains. For more information on the Rational Method and other hydrological methods refer to Chapter 7 - Hydrology.

Estimated peak flows will be based on the existing runoff conditions and an allowance for the reasonably foreseeable future developments and conditions. The future flow patterns and basin sizes should be based on present topographic conditions if specific plans for developed modifications are unknown.

13.2.3 Design Frequency And Spread Width The major consideration for selecting a design frequency and spread width is the highways classification, because it defines and reflects public expectations for finding water on the pavement surface.

Ponding should be avoided on the traffic lanes of high-speed, high-volume highways, where it is not expected to occur.

Highway speed is another major consideration, because at speeds greater than 45mph, even a shallow depth of water on the pavement can cause hydroplaning and safety problems to motorists.

Design speed is recommended for use in evaluating hydroplaning potential. When the design speed is selected, consideration should be given to the likelihood that legal posted speeds might be exceeded. It is clearly unreasonable to provide the same level of protection for low speed facilities as for high speed facilities.

For curb and guttered roadways with no parking, it is not practical to avoid all travel lane flooding when longitudinal grades are flat (0.3 to one percent). However, flow spread width shall never exceed the lane adjacent to the gutter for design conditions. Municipal bridges with curb and gutter should also use this criterion. For single lane roadways at least 8 ft of roadway shall remain unflooded for design conditions.

Storm drain systems are normally designed for full gravity flow conditions using the design frequency discharges.

The exceptions are depressed roadways and underpasses where ponded water can be removed only through pumps via the storm drain systems. In these situations, a larger design frequency is advisable for the inlets at the sag location and for sizing the main storm drain line.

Table 3.2 presents the Design Frequency vs.

Spread Width.

13.2.4 Inlet Spacing The time of concentration (tc) for inlet spacing is the time for water to flow from the hydraulically most distant point of the drainage area to the inlet, which is known as the inlet time. Usually this is the sum of the time required for water to move across the pavement or overland back of the curb to the gutter, plus the time required for flow to move through the length of gutter to the inlet. For pavement drainage, when the total time of concentration to the upstream inlet is less than 5 min, a minimum tc of 5 min should be used to estimate the intensity of rainfall. The time of concentration for the second downstream inlet and each succeeding inlet should be determined independently, the same as the first inlet. For a constant roadway grade and relatively uniform contributing drainage area, the time of concentration for each succeeding inlet could also be constant.

–  –  –

Note: These criteria applies to shoulder widths of 4 ft or greater. Where shoulder widths are less than 4 ft, a minimum design spread of 4 ft should be considered.

–  –  –

Pages:   || 2 | 3 | 4 | 5 |

Similar works:

«dinero por hacer encuestas dinero por hacer encuestas Ganando Dinero Por Encuestas Ganando Dinero Por Encuestas. Ad #: así ganar aún más dinero, ¡y por eso pagan muy bien! Lo major es que TODOS pueden hacer encuestas pagas. Ganar con encuestas y mas con InstaGC | Ganar dinero por hacer encuestas es posible, y esta web pretende ayudaros a ello. Aqui debajo teneis una lista de páginas web que pagan por hacer Ganar Dinero por Hacer Encuestas Ganar Dinero por Hacer Encuestas. 72 likes ·...»

«MA Dissertation’ Mr MD Nin [2011] University of Central Lancashire Faculty of Arts, Humanities & Social Sciences Northern School of Design Postgraduate Project/Dissertation DE4115 2010/11 Project/Dissertation „The Great Divide‟ Is there a useful connection between science and art? Matthew D Nin (MA Ceramics) www.mattninceramics.wordpress.com | www.hands-onclay.co.uk 1 MA Dissertation’ Mr MD Nin [2011] 1. Introduction Throughout my practice over the years within Art & Design, when given...»

«Corrected Transcript 06-Sep-2016 The W illiams Cos., Inc. (W MB) Barclays CEO Energy Power Conference Total Pages: 12 1-877-FACTSET www.callstreet.com Copyright © 2001-2016 FactSet CallStreet, LLC The Williams Cos., Inc. Corrected Transcript (WMB) Barclays CEO Energy Power Conference 06-Sep-2016 CORPORATE PARTICIPANTS Alan S. Armstrong President and Chief Executive Officer, The Williams Cos., Inc. OTHER PARTICIPANTS Christine Cho Analyst, Barclays Capital, Inc. MANAGEMENT DISCUSSION SECTION...»

«252 Groups August 2016, Week 4 Large Group 4-5 (Tipp) The Test Bible Story: The Test (Abraham and Isaac) • Genesis 18, 21, 22 (Supporting: Genesis 15) Bottom Line: I should trust and obey because there’s a bigger plan. Memory Verse: “Trust in your leaders. Put yourselves under their authority. Do this, because they keep watch over you.” Hebrews 13:17a, NIrV Life App: Obedience—trusting those who lead you by doing what you’re asked to do. Basic Truth: I can trust God no matter what....»

«Manager Adams Street Partners Address 1 N. Wacker Dr. Suite 2200 Chicago IL 60606 Contact John Gray Phone 312-553-8482 Email jgray@adamsstreetpartners.com Product Adams Street Partnership Funds Asset Class Private Equity Market Value Quartery Fees Service ASP operates a pooled vehicle of private equity fund of funds, and th Chicago Police is a participant in the vehicle. The fund is a portfolio of multiple private partnerships investments that are diversified by time, managers and sub-class....»

«This report presents a macro and micro view of Microfinance Institutions’ compliance with the Code of Conduct and Fair Practices Code prescribed by the Microfinance Institutions Network, Sa-Dhan and the Reserve Bank of India. The report consolidates the ndings of wide-ranging Code of Conduct Assessment studies that were conducted with fty Indian MFIs by ve rating and evaluation companies. MicroSave Market-led solutions for financial services Code Of Conduct Assessment For Microfinance Sector...»

«Owner’s Manual for multi-speed bicycles 7th Edition, 2004 IMPORTANT: This manual contains important safety, performance and service information. Read it before you take the first ride on your new bicycle, and keep it for reference. Additional safety, performance and service information for specific components such as suspension or pedals on your bicycle, or for accessories such as helmets or lights that you purchase, may also be available. Make sure that your dealer has given you all the...»

«ROBUST MINIMALITY OF ITERATED FUNCTION SYSTEMS WITH TWO GENERATORS ALE JAN HOMBURG AND MEYSAM NASSIRI Abstract. We prove that every compact manifold without boundary admits a pair of diffeomorphisms that generates C 1 robustly minimal dynamics. We apply the results to the construction of blenders and robustly transitive skew product diffeomorphisms. Contents 1. Introduction 1 2. Minimal iterated function systems 3 3. Alternative construction 5 4. Strong robust minimality 8 5. Skew products...»

«Capacity Choice, Momentum and Long-term Reversals∗ Kevin Aretz† and Peter F. Pope‡ Abstract A real options-based firm valuation model predicts that the momentum and long-term reversal effects in stock returns arise through an excess capacity channel linked to expected returns. Our model predicts that (i) momentum losers have mild excess capacity, resulting in expected returns that are lower than for momentum winners; and (ii) long-term losers have higher excess capacity and lower...»

«IgBILL ® Ig® Nobel Prize Ceremony 2015 This Year’s Theme: Life Twitter: #IgNobel About the Ig Nobel Prizes Ig Nobel Prizes are awarded for achievements that first make people LAUGH, and then make them THINK. The Igs are intended to spur public curiosity and interest in science and other fields of endeavor. Ten prizes are awarded each year. Winners travel to the ceremony at their own expense. The Ig Nobel Prize winners are, despite possible appearances to the contrary, real. Their...»

«Promoting the conservation and use of underutilized and neglected crops. 20. Peach palm Bactris gasipaes Kunth Jorge Mora-Urpí, John C. Weber and Charles R. Clement t Genetic Reso lan ur lP ce na s In tio Interna stitute IPGRI Peach palm. Bactris gasipaes Kunth 2 The International Plant Genetic Resources Institute (IPGRI) is an autonomous international scientific organization operating under the aegis of the Consultative Group on International Agricultural Research (CGIAR). The international...»

«Corporate Governance Statement The Hague, March 2016 aegon.com 1. Dutch Corporate Governance Code comply or explain As a company based in the Netherlands, Aegon N.V. (also being referred to as the “Company”) adheres to the Dutch Corporate Governance Code. The complete text of the Code can be found on www.commissiecorporategovernance.nl. Aegon endorses the Code and strongly supports its principles for sound and responsible corporate governance. Aegon regards the Code as an effective means of...»

<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.