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EA204 Environmental Technology Pavement Drainage Stormwater Sewer Design.

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Presentation on theme: "EA204 Environmental Technology Pavement Drainage Stormwater Sewer Design."— Presentation transcript:

1 EA204 Environmental Technology Pavement Drainage Stormwater Sewer Design

2 Objectives of Pavement Drainage n to collect stormwater on the surface and move it into the minor system (i.e. gutters, catchbasins, ditches) n to maintain a safe driving surface for the movement of traffic

3 Road Cross-Section: RURAL n rural cross-sections have ditches n normal crossfall is 2% 2.0% 2.0% Centre line (crown) Shoulder Ditch Side Slope Back Slope Lane

4 Road Cross-Section: URBAN n urban sections have curb, gutter, catchbasins, and storm sewers 2.0% 2.0% Centre line Curb & Gutter Boulevard Lane Sidewalk PropertyLine Storm Sewer PropertyLine

5 Minimum Pipe Sizes n min diameter for storm sewers mm n min diameter for service leads mm n reduces chance of objects getting stuck n enables maintenance & cleaning

6 Minimum Cover Depth n below depth of frost penetration n below 1.2 m to avoid crushing from large trucks n below water supply n above sanitary sewer system

7 Flow Velocities n Velocity in pipes is controlled by many elements: slope hydraulic radius roughness of pipe’s inside surface

8 Min & Max? n Minimum velocities are set to prevent sedimentation in pipes (this would reduce pipe cross-section and capacity) n Maximum velocities are set to prevent scouring and premature wear in pipes (large objects will not be carried through pipes and damage them)

9 Manhole Spacing Stormwater sewers run in straight lines on a constant slope from one manhole to the next: n alignment (bearing) n slope (%) n pipe size (diameter in mm) n maintenance limitations

10 Manhole Spacing n whenever a sewer changes direction (bearing) we need a manhole n when the slope of a sewer changes we need a manhole n alignment (plan) n slope (profile)

11 Manhole Spacing n a manhole is needed when we change the size of sewer n manholes are needed so we can get in and clean and repair sewers n diameter (mm) n maintenance

12 Catchbasin & Inlet Spacing Water must be “caught” before it becomes a hazard: n road grade and low points (sags) n crossfall and roadwidth n design storm n pedestrian crosswalks n intersections n public and private driveways

13 Catchbasin & Inlet Spacing n steeper grades require closer spacing to keep velocity in gutter low n double inlets are needed to handle water from both sides of sag n road grade n low points (sags)

14 Catchbasin & Inlet Spacing n inlets needed where water moves from crown to curb & gutter n wider roads mean more water and closer spacing n crossfall n road width

15 Catchbasin & Inlet Spacing n higher return times mean more water and closer spacing to intercept water n inlets must be located immediately upstream of ped crosswalks n design storm n pedestrian crosswalks

16 Catchbasin & Inlet Spacing n inlets must be located upstream of intersection to prevent “rivers” flowing through intersection n inlets must be located at least 1.5m away from driveways n intersections n private & public driveways

17 Catchbasin & Inlet Spacing Cross SectioncPlan View L Crest Min. Drive Width


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