×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Hydraulic calculation storm sewer network using the Rational method

## Hydraulic calculation storm sewer network using the Rational method

(OP)
Hello!

1. I would like to ask a question about the slopes that are used in the hydraulic calculation of rainwater networks. As far as I understand, the estimated bias of the rainwater drainage network can be accepted by anyone, provided that it provides Vfull>Vmin and Qfull>Qdes For example, 0.001; 0.0015; 0.002; 0.0025; 0.003; 0.0035; 0.004; 0.0045; 0.005 and so on. Or even 0.0011; 0.0012; 0.0013; 0.0014; 0.0015; 0.0016; 0.0017; 0.0018; 0.0019 or 0,0035; 0,0036; 0,0037; 0,0038; 0,0039; 0,0041 i.e. a finer ranking than in the example above. That is, modern equipment during the construction of the network can provide such a small ranking (0,0014; 0,0015; 0,0016) and can create any slope of the pipe?

2. And as far as I understand, is the maximum maximum rainfall rate in the rainwater drainage network 12 feet per second?

### RE: Hydraulic calculation storm sewer network using the Rational method

Its been years since i have done drainage design but to me providing drainage levels to more than 0.001m is rediculous. I think the same to gradients to more accuracy than 0.01%. Yes there are levels etc that can read more accurately but can you get the guy or gal down at the bottom of a trench in the lashing rain to do it. Probably not.

I thought 4m/s (13ft/s) was the limit to avoid internal erosion of concrete pipes. Again its been years since i have looked at a drainage design.

### RE: Hydraulic calculation storm sewer network using the Rational method

(OP)
Thank you for your answer. I'm interested in slopes for sewer networks. I know about the minimum slopes and the fact that they are regulated by the minimum speeds that prevent the formation of sediment in the pipeline. But I'm not interested in the minimum biases, I'm interested in the biases that you can create during the design and what they can be, or rather, I'm interested in the ranking. Which of the proposed options is correct?
1) 0.001; 0.0015; 0.002; 0.0025; 0.003; 0.0035; 0.004; 0.0045; 0.005 ranking through 0.0005 (that is, it is possible to set the slope multiple of 0.0005 during the calculation)??????
2) 0,0011; 0.0012; 0.0013; 0.0014; 0.0015; 0.0016; 0.0017; 0.0018; 0.0019 ranking through 0.0001 (when calculating, it is possible to accept any slope)??????
!!!!!I'm interested in what slope values can be taken when designing sewage networks!!!!

### RE: Hydraulic calculation storm sewer network using the Rational method

This can be computed externally using pipe hydraulics and Manning's Equation. One must make some assumptions; i.e. non-pressure flow and either partial or full flow. I have set up a spread sheet.

### RE: Hydraulic calculation storm sewer network using the Rational method

I do not know what you mean by ranking?

All i know is that i see too many digits after a decimal point....

### RE: Hydraulic calculation storm sewer network using the Rational method

For the most sewer network design, the recommended minimum pipe slope is 0.5% or 0.005. Anything flatter than that will just not drain effectively and sediments likely to accumulate.
Also, construction issues arises due to specialized tool - Laser level - required to install the pipe. The contractor will have a difficult effort staying within specified tolerance (+/-), especially when the length of the pipe is more than 50-ft.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

White Paper - How to Capitalize on HVAC/R Trends to Drive Business Growth
According to Steve Yurek, CEO of the Air Conditioning, Heating and Refrigeration Institute, the HVAC/R industry is facing change on all fronts. This includes challenging trends on contractors and distributors like new refrigerants, growing automation, complex sensors and monitoring, green initiatives and a technician shortage. We look at these trends and outline actionable insights on how it all can be turned into a competitive advantage and business opportunity. Download Now
eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!