×
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

little cover for pvc storm sewer pipe in grass area?
2

little cover for pvc storm sewer pipe in grass area?

little cover for pvc storm sewer pipe in grass area?

(OP)
I have a situation where I only have 12" of cover for a pcv pipe to catchbasin connection? The pipe is in a grassed area that would not expect any vehical loading.  

Is there a problem associated with having storm pipes above the frost line? It's done all the time right?

Another problem I am facing is that I am forced to connect to a catchbasin directly below the frame. Can this connection physically be made?

Thanks.

RE: little cover for pvc storm sewer pipe in grass area?

The cover is too lean as such you should try to protect it by engrooving i.e providing a cover with another pipe preferably(metal. If the location is in such a place that it is exposed to the risk of congelling due to frost, lag the pipe before engrooving it , then build another frost protection for the engrooving pipe with a material that has a high insulating property. Try as much as possible to provide the system with good drainage like by providing a rest bed of sand and gravel.
As to your second question, I do not understand it as such can not profer an answer to it. Good luck
Teddy

RE: little cover for pvc storm sewer pipe in grass area?

as long as you have posative drainage in the pipe, freezing of the pipe should not be a problem.  Encapsulate the basin and pipe with non frost susceptible backfill

you will probably need to modify the structure to allow the connection below the frame.

RE: little cover for pvc storm sewer pipe in grass area?

Of course, each spring you will have a small lake there. the spring run off will freeze inside the pipe if the ground is frozen and you get snowmelt.

Richard A. Cornelius, P.E.
WWW.amlinereast.com

RE: little cover for pvc storm sewer pipe in grass area?

.
I'm in the southeast - surface water freezing is usually only a few days per year (if that), so I can't comment on the freezing issues.

If you have heavy traffic loading (emphasis on weight much more than cycles), then the cover might be a concern. In the situation you described, 12 inches should be more than enough. (You could probably drive a loaded pickup over that in decent soils and not have a problem - depending on the pipe, bed and backfill construction method/care).

I rarely see these small pipes and low-head inlets work well - often failing within a year after installation - but it does depend on the watershed. The problem I see is inlet/pipe clogging. If this system is in an "ultra-urban" area (near 100% paved/impervious surface) with no trash, debris, or sediment, then the system might work okay.

I don't use anything less than a 15" diameter pipe for stormwater conveyance and only that if all inlets have fully grated covers. Otherwise, 18" diameter is the minimum I use. The one exception to this is roof drains - to which I might connect 8" or 12" diameter pipes. Have you checked out other installations in similar areas to assess how well those are functioning? This is not about the clean water hydraulics - this is about the clogging. The hydraulic analysis may very well show that everything is fine with a 4" diamater pipe, but that is not reality in most cases - larger pipes are needed to address clogging. The 4" diamater might might need to be an 18" diameter pipe to prevent clogging failure.

Connecting just below the grate should be no problem physically, but the resultant low forcing head at the inlet would likely be a problem.
.

tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation
http://hhwq.blogspot.com

RE: little cover for pvc storm sewer pipe in grass area?

almost every drain pipe we design in my Vermont town is above the frost line.

The town storm sewer system at the street is above the frost line. Most of the work we mess around with are urban rehabilitation projects where you can't adjust the grades much. it makes it a real b###h to get below the frost line, drain, and tie-in. thumbsup

if you want a little extra security, you can squeek some blueboard over the tiny trench.

2nd question: it depends...

RE: little cover for pvc storm sewer pipe in grass area?

If the basin that you are connecting to is deeper, (you are attaching just below the grate), then why not bury the storm pipe deeper and match 0.8 x crown elevation?

RE: little cover for pvc storm sewer pipe in grass area?

It appears there may be some concerns voiced by others on this thread (re loading etc.)  I would only add a wonder also if twelve inches of cover, in a "grassy" area, is enough to dependably prevent a quite lightweight, smooth (at least on the outsides?), and sizeable? pipe (that might at times be empty?) from moving/floating?

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