• InfoDrainage

Designing pipes for no surcharge criteria

Design pipes to meet no-surcharge criteria by setting the network design criteria.


00:04

for drainage designs to be valid, they have to meet two criteria.

00:08

No surcharge and no flood

00:11

pipes have to be sized adequately

00:13

and effective storage solutions need to be built.

00:17

Once you have decided on which rainfall methodology will work for your site,

00:21

you can begin to create the drainage network in your model,

00:24

starting with the no surcharge state.

00:27

Notice that this model already has catchment areas set up

00:30

with a manhole in each and pipes connecting the manholes.

00:35

The flow arrows between the pipes designate the flow direction.

00:39

In addition,

00:40

some rainfall data has already been configured

00:43

with the Fs are parameters return periods

00:46

and storm durations

00:48

if not on the ribbon rainfall pollutants tab rainfall panel,

00:53

click the rainfall manager to open it

00:57

browse to and open the design rainfall dot I D R X file from the data directory

01:02

and then click ok to exit the rainfall manager.

01:07

Now it is time to size the pipe correctly for the no surcharge state or stage one

01:13

on the ribbon,

01:14

click the preliminary sizing tab and in the

01:17

network design panel click network design criteria.

01:21

This opens the network design criteria, dialog box to the flow options tab here,

01:27

you create the rules that constitute the no surcharge state for the inflows

01:33

in the panel, you designate what type of storm will be in the study

01:38

for this exercise.

01:39

Use a saved rainfall data file,

01:42

Click the from library radio button and then expand the drop down and select rain one

01:49

as soon as you do the parameters for rain one appear below the drop down in the panel.

01:55

Below that are the minimum time of entry in minutes

01:58

and the maximum travel time also in minutes,

02:03

the time of entry is the amount of time it takes the

02:05

rainfall to run across the catchment surface and enter the manhole.

02:10

The catchment boundaries determine the surface area that is covered.

02:14

For more guidance on that,

02:16

refer to the Wallingford procedure

02:19

For this exercise. Keep the time of entry set at five minutes.

02:24

The maximum travel time is the amount of time

02:27

that the water will flow through the pipes.

02:30

First note that the peak flow calculation is set to the UK modified Rational Method,

02:35

which recognizes that the duration of the storm

02:38

is often longer than the time of concentration.

02:41

Therefore 30 minutes is a very generous amount of

02:44

time for the water to flow through the pipes

02:47

now that the inflows are set.

02:49

Click the design options tab to design the pipes

02:53

in the top group. Are the pipe options

02:55

First designate the pipe size library you are using for your project.

03:01

This is already set to default which

03:03

contains common pipe sizes in regular increments.

03:06

For example,

03:08

the UK standard would started 100 or

03:13

increase in 75 millimeter increments such as 152 125 303 175 455 125 et cetera.

03:28

The U.

03:28

S standard would start with a three inch pipe and increase by

03:32

three inch increments such as nine inches 12 inches 15 inches etcetera.

03:39

If you have your own library of pipe sizes you can click the browse button,

03:44

select the file and load the library for this exercise.

03:48

Leave the library set to default,

03:52

expand the lock slope options drop down.

03:55

This option allows you to lock the slope in certain cases but for this exercise

03:60

leave it as none to give the program as much freedom as possible.

04:03

To set the slopes in the design for you

04:06

along with the sizes and gradients for the pipes.

04:10

The next decision you need to make is how the

04:12

pipes are going to transition when they change in size.

04:16

When the pipes change from a smaller diameter to a larger diameter

04:20

such as when they come to a manhole.

04:22

They will be laid either soffit to soffit or invert to invert

04:27

when they are laid. Soffit to soffit

04:29

the tops of both pipes are even

04:31

and the bottoms are not

04:33

so that the larger pipe is laid slightly deeper than the smaller pipe

04:37

when they are laid. Invert to invert the opposite happens

04:41

where the bottoms of both pipes are even and the top of

04:44

the larger pipe is higher than the top of the smaller pipe.

04:48

For most builds.

04:49

The best practice is to keep the soffits level so expand the design level. Drop down

04:55

and select level. Soffits.

04:58

Next is the minimum cover depth which is the depth

05:01

at which the pipes are to be installed in the ground

05:04

a depth of 1.2 m below a road surfaces. Standard from the D. C. G. Regulations

05:11

for walkways or open land. The depth can be 0.6 m.

05:16

The depth value can be changed globally here or you can change

05:20

the depth of individual pipes when working in the table view for pipes

05:25

next under slopes, you can set the minimum slope and maximum slope values

05:31

For this exercise. Lead the set to the defaults of 540 respectively.

05:38

Also ensure that check velocity is enabled and that the minimum velocity

05:43

and maximum velocity values are not too low nor too high.

05:48

Again, leave these set at the default values of 1.0 and 3.0.

05:54

If both the slope and velocity levels are too low,

05:57

there could be siltation or stagnant water in the pipes

06:01

and if they are set too high

06:02

then the fast moving water could cause damage or where to the infrastructure.

06:08

Notice the option to allow backdrops, which some local authorities allow.

06:12

A backdrop may be needed when pipes are placed

06:15

in a steep hill such that the upper pipe enters

06:18

the manhole toward the top and the next pipe

06:21

exits the manhole at the bottom of the manhole.

06:23

Leave this option off for this exercise.

06:27

Other pipe options in this group include limiting the pipe

06:30

full conditions using flow restrictions or reducing channel depths.

06:37

Leave these all d Selected.

06:39

The bottom group allows you to set the manhole options.

06:43

If you keep the option to allow manhole sizing on

06:46

the program assumes that the bigger the pipe,

06:48

the bigger the manhole needed to house it.

06:51

If you have a manhole sized library you want to use,

06:54

you could click the browse button and load that library here.

06:59

Leave the apply offset option off,

07:02

click okay.

Video transcript

00:04

for drainage designs to be valid, they have to meet two criteria.

00:08

No surcharge and no flood

00:11

pipes have to be sized adequately

00:13

and effective storage solutions need to be built.

00:17

Once you have decided on which rainfall methodology will work for your site,

00:21

you can begin to create the drainage network in your model,

00:24

starting with the no surcharge state.

00:27

Notice that this model already has catchment areas set up

00:30

with a manhole in each and pipes connecting the manholes.

00:35

The flow arrows between the pipes designate the flow direction.

00:39

In addition,

00:40

some rainfall data has already been configured

00:43

with the Fs are parameters return periods

00:46

and storm durations

00:48

if not on the ribbon rainfall pollutants tab rainfall panel,

00:53

click the rainfall manager to open it

00:57

browse to and open the design rainfall dot I D R X file from the data directory

01:02

and then click ok to exit the rainfall manager.

01:07

Now it is time to size the pipe correctly for the no surcharge state or stage one

01:13

on the ribbon,

01:14

click the preliminary sizing tab and in the

01:17

network design panel click network design criteria.

01:21

This opens the network design criteria, dialog box to the flow options tab here,

01:27

you create the rules that constitute the no surcharge state for the inflows

01:33

in the panel, you designate what type of storm will be in the study

01:38

for this exercise.

01:39

Use a saved rainfall data file,

01:42

Click the from library radio button and then expand the drop down and select rain one

01:49

as soon as you do the parameters for rain one appear below the drop down in the panel.

01:55

Below that are the minimum time of entry in minutes

01:58

and the maximum travel time also in minutes,

02:03

the time of entry is the amount of time it takes the

02:05

rainfall to run across the catchment surface and enter the manhole.

02:10

The catchment boundaries determine the surface area that is covered.

02:14

For more guidance on that,

02:16

refer to the Wallingford procedure

02:19

For this exercise. Keep the time of entry set at five minutes.

02:24

The maximum travel time is the amount of time

02:27

that the water will flow through the pipes.

02:30

First note that the peak flow calculation is set to the UK modified Rational Method,

02:35

which recognizes that the duration of the storm

02:38

is often longer than the time of concentration.

02:41

Therefore 30 minutes is a very generous amount of

02:44

time for the water to flow through the pipes

02:47

now that the inflows are set.

02:49

Click the design options tab to design the pipes

02:53

in the top group. Are the pipe options

02:55

First designate the pipe size library you are using for your project.

03:01

This is already set to default which

03:03

contains common pipe sizes in regular increments.

03:06

For example,

03:08

the UK standard would started 100 or

03:13

increase in 75 millimeter increments such as 152 125 303 175 455 125 et cetera.

03:28

The U.

03:28

S standard would start with a three inch pipe and increase by

03:32

three inch increments such as nine inches 12 inches 15 inches etcetera.

03:39

If you have your own library of pipe sizes you can click the browse button,

03:44

select the file and load the library for this exercise.

03:48

Leave the library set to default,

03:52

expand the lock slope options drop down.

03:55

This option allows you to lock the slope in certain cases but for this exercise

03:60

leave it as none to give the program as much freedom as possible.

04:03

To set the slopes in the design for you

04:06

along with the sizes and gradients for the pipes.

04:10

The next decision you need to make is how the

04:12

pipes are going to transition when they change in size.

04:16

When the pipes change from a smaller diameter to a larger diameter

04:20

such as when they come to a manhole.

04:22

They will be laid either soffit to soffit or invert to invert

04:27

when they are laid. Soffit to soffit

04:29

the tops of both pipes are even

04:31

and the bottoms are not

04:33

so that the larger pipe is laid slightly deeper than the smaller pipe

04:37

when they are laid. Invert to invert the opposite happens

04:41

where the bottoms of both pipes are even and the top of

04:44

the larger pipe is higher than the top of the smaller pipe.

04:48

For most builds.

04:49

The best practice is to keep the soffits level so expand the design level. Drop down

04:55

and select level. Soffits.

04:58

Next is the minimum cover depth which is the depth

05:01

at which the pipes are to be installed in the ground

05:04

a depth of 1.2 m below a road surfaces. Standard from the D. C. G. Regulations

05:11

for walkways or open land. The depth can be 0.6 m.

05:16

The depth value can be changed globally here or you can change

05:20

the depth of individual pipes when working in the table view for pipes

05:25

next under slopes, you can set the minimum slope and maximum slope values

05:31

For this exercise. Lead the set to the defaults of 540 respectively.

05:38

Also ensure that check velocity is enabled and that the minimum velocity

05:43

and maximum velocity values are not too low nor too high.

05:48

Again, leave these set at the default values of 1.0 and 3.0.

05:54

If both the slope and velocity levels are too low,

05:57

there could be siltation or stagnant water in the pipes

06:01

and if they are set too high

06:02

then the fast moving water could cause damage or where to the infrastructure.

06:08

Notice the option to allow backdrops, which some local authorities allow.

06:12

A backdrop may be needed when pipes are placed

06:15

in a steep hill such that the upper pipe enters

06:18

the manhole toward the top and the next pipe

06:21

exits the manhole at the bottom of the manhole.

06:23

Leave this option off for this exercise.

06:27

Other pipe options in this group include limiting the pipe

06:30

full conditions using flow restrictions or reducing channel depths.

06:37

Leave these all d Selected.

06:39

The bottom group allows you to set the manhole options.

06:43

If you keep the option to allow manhole sizing on

06:46

the program assumes that the bigger the pipe,

06:48

the bigger the manhole needed to house it.

06:51

If you have a manhole sized library you want to use,

06:54

you could click the browse button and load that library here.

06:59

Leave the apply offset option off,

07:02

click okay.

Step-by-step:

Once you have decided on which rainfall methodology will work for your site, you can begin to create the drainage network in your model, starting with the no-surcharge state.

The example model already has catchment areas set up, with a manhole in each and pipes connecting the manholes. The flow arrows between the pipes designate the flow direction.

Ensure the rainfall data has been configured with the FSR parameters, return periods and storm durations by loading the rainfall data:

  1. On the ribbon, Rainfall Pollutants tab, Rainfall panel, click Rainfall Manager.
  2. In the Rainfall Manager toolbar, click Open.
  3. Browse to and open the file design rainfall.idrx.
  4. Click OK.
    The InfoDrainage interface, with the Rainfall Manager open behind the Open dialog box. The rainfall study file has been chosen and the user is about to click Open.
  5. Click OK to exit the Rainfall Manager.

Now, it is time to size the pipe correctly for the no-surcharge state, or Stage 1:

  1. On the ribbon, Preliminary Sizing tab, Network Design panel, click Network Design Criteria.
  2. In the Network Design Criteria dialog box, Flow Options tab, enable From Library.
  3. Expand the drop-down and select Rain 1.
  4. Keep the Time of Entry set to 5 minutes.
  5. Set the Maximum Travel Time to 30 minutes.
    The Network Design Criteria dialog box, with the Flow Options tab active and all applicable settings configured.
  6. Click the Design Options
  7. For the Pipe Size Library, select Default.
  8. Optional: If you have your own library of pipe sizes, you can click the Browse () button, select the file, and load the library.
  9. Expand the Lock Slope drop-down and select None.
  10. Expand the Design Level drop-down and select Level Crowns (Soffits).
  11. Set Slope to 500.
  12. Set Slope to 40.
  13. Enable Check Velocity.
  14. Set Min Velocity to 0 m/s.
  15. Set Max Velocity to 0 m/s.
  16. Deselect:
  • Allow Backdrops
  • Limit Pipe Full Conditions
  • Use Flow Restriction
  • Reduce Channel Depths
  • Exclude Branch Lines
  • Apply Offset
  1. Keep the option to Allow Manhole Sizing
  2. Optional: If you have your own Manhole Size Library, you can click the Browse () button, select the file, and load the library.
  3. Click OK.
    The Network Design Criteria dialog box, with the Design Options tab active and all applicable settings configured.
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