×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*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.

Students Click Here

Jobs

Energy dissipation in steep paved ditch.

Energy dissipation in steep paved ditch.

Energy dissipation in steep paved ditch.

(OP)
We are rehabilitiating a low volume rural road (~300 vpd, sl=55 mph), and at one end, we have an asphalt paved ditch that is deteriorating. It's about 900 ft long on a 5-10% grade. Currently, vegetation growing in the thermal cracks provides some energy dissipation and filtration.

I'm looking for ideas for weirs, checkdams, etc. to manage the velocity and maybe improve water quality. It is in the road's clear zone, so I don't want anything that will cause an undue hazard to anyone that drifts into the ditch. Also, the right of way line is about 12 ft from the edge of shoulder.

Any suggestions?

RE: Energy dissipation in steep paved ditch.

I don't know if this will work for your situation, but I have used CMU blocks set a couple of inches into concrete ditch pavement. It has worked well in the few situations I've used it, but I haven't used this method in areas likely to be impacted by traffic.

RE: Energy dissipation in steep paved ditch.

Considering you are in the clear zone with a relatively high design speed, your options are limited.

Not sure what the budget is, but you could consider a set of storm sewer inlets to decrease the energy/erosion potential.

Maybe grouted riprap ditch with low profile (embedded) angular rock?

I also think you can use the CMU blocks mentioned above - which can include a design to allow vegetation to grow in the voids.

RE: Energy dissipation in steep paved ditch.

What's your budget? Location? Soils? My first thought is cut a one foot section out of the center of the ditch along its length and backfill with a couple feet of washed 57 stone, then cap it with pervious concrete or porous pavers. You'd maintain the conveyance capacity of the channel in big storms while promoting groundwater infiltration in smaller ones.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Energy dissipation in steep paved ditch.

angular riprap or gabions might work. not sure how any sort of concrete will help to manage velocity without energy dissipation. if you want to maintain concrete, then use drop structures to reduce the effective slope of the channel so the froude number is below 1, or better yet below .8

RE: Energy dissipation in steep paved ditch.

Pervious pavement would manage velocity by sucking the water up into the stone and infiltrating it. The only events with any velocity at all would be the ones that fill the entire infiltration trench.

But that's just one idea.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Energy dissipation in steep paved ditch.

there is no way that pervious pavement would be effective at 10% slope

RE: Energy dissipation in steep paved ditch.

Wow, 10% grade is toublesom. you may want to consult HEC14 and look at roughening for an increase in mannings, no even sure that would work. Have you considered collecting and conveying with storm drain pipes?

RE: Energy dissipation in steep paved ditch.

You could achieve the same basic premise with a slot drain into an infiltration bed.

There's really no other way to get any sort of 'water quality' element into this, as far as I can see, due to the grades.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Energy dissipation in steep paved ditch.

Need to get that channel grade down to ~2% with grouted riprap rundowns every ~200'.

RE: Energy dissipation in steep paved ditch.

(OP)
LincolnPE, the grade of the adjacent road is 5 - 10%, and I can't justify the costs of reducing the grade on a low volume rural road with a good safety record.

Has anyone tried the erosion control matting or reinforced vegetation on grades this steep? The sales reps will promise the stars, but I'm interested in real world results.

http://www.nagreen.com/erosion-control-products/vm...
http://www.acfenvironmental.com/TurfReinforcementM...


RE: Energy dissipation in steep paved ditch.

Crickets...smile

RE: Energy dissipation in steep paved ditch.

Japanese Knotweed or something of that ilk... you either need to terrace it or build a series of walls or use angular BFR's... (big rocks) to dissipate the energy.

Dik

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.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources