Drainage Quote

Why don't you just ask the contractor?

The CR4 ( SDR 41) designation relates to stiffness, there's 2, 4, and 8...

So I believe this is smooth pipe that is used for drainage....

http://sotici.com/WordPresSotici/tubes-pvc-assainissement/?lang=en

I believe the 90ml means 90 meters linear or length...about 300ft...

Yes thats right, I worded the question badly! It was the CR4 bit I didn't understand!

Thanks

Its 9pm here and I'm impatient to know having just got home from work and picked up the quote by email. I do not want to call the contractor at this time, especially at the weekend. I hope that is ok with you? If not, I'll understand.

So as I understand it, having followed your link, CR4 relates to the stiffness of the pipe; As suspected, the mention of CR4 in the quote will not help me understand the dimensions of the pipe. When it comes to the price of the pipe, I think the dimensions are more critical, seeing as you seem to be able to get CR4 in many sizes.

My guess is that the quote is for 90 meters of 110mm PVC drain pipe.

I hope its not 110mm, I was hoping for a minimum of 300mm. Thanks to all, looks like I'll have to wait til Monday and speak to the contractor.

I think Solar Eagle hit this one squarely. CR4 is the American equivalent of the Dimension Ration (DR) 41. This is a pipe intended for pressure applications. Another way of classifying the wall thickness is Pressure Class.

I do think that the 90 mL is more likely the ID and not a length. A soft conversion is 3.5 inches.

This pipe does not have ribs.

The wall thickness of this pipe is about 0.1 inches. If I was specifying a pipe like this in America, I would not go less than Schedule 40. That has a wall thickness of 0.22 inches.

I suggest you bump the wall thickness up. And, 3.5 inch dia is likely to become plugged. Make sure the inlets do not let debris in or consider increasing the diameter of this pipe.

If it is PVC, it is unlikely to be ribbed.

Google seems to think that CR4 PVC is a Cosmetic Ring for 4 inch PolyVinyl Chloride pipe.

Corrugated pipe is almost always polyethylene.

Not sure what 90ml means in this context.

Ok, I've not seen the smooth pipe in a size bigger than 120mm, I guess it must exist....?

Yes I think in this grade up to 300mm....

https://flexpvc.com/Reference/FullPVCPipeChart.shtml

and beyond...up to at least 24" ID.

Show a link...

From Fith Edition of Handbook of PVC Pipe Design and Construction

http://www.ipexna.com/media/4205/big-brute-brochure-international.pdf

Corrugated pipe follows the curves of the landscape; it is bent to fit when it is installed.

First, you should be asking ''How big is the relevant watershed within which the adjacent field lies?'', etc. ...

After which, the (County?) can then give you much of the data needed to adequately ''size'' the drainage conduit(s), etc. ...

After which, you can select an appropriate conduit type, material, configuration, etc., and evaluate the need for appropriate regrading, slopes, etc. ...

This contractor is not proposing to regrade any of the landscape. Two sides of the adjacent field are uphill of the garden, they converge in to a corner which will take the drainage pipe. The two sides will be ditched, the natural fall taking the water in those ditches to the new drainage pipe.

Given the field is obviously soil, what is the best way to protect the entrance of the drainage pipe from blocking? The local ditches get overwhelmed with flood water once every 5 years or so.

Usually, you dig a trench, you line the trench with filter fabric, place some clean gravel in the bottom of the trench, place the drain pipe and cover with gravel, wrap over the filter fabric and cover to grade with more clean gravel. The object is to provide relatively free drainage into the pipe ports and prevent silt and mud from working into the drain pipe. On some installations a standpipe is put at the high end to allow periodic flushing/cleaning of the drain pipe.

https://www.fairfaxcounty.gov/soil-water-conservation/drainage-problem-control-runoff

A couple of things:

ccoop609, OP has already indicated he desires larger than 4" pipe.

Jpfalt, this is solid, non-perforated pipe. It is designed to withstand moderate internal pressure.

Lyn, you are right that the only CR4 shown as CR4 is smooth, non-perforated. My comment was related to the installation to prevent fines from entering the drain pipe provided that holes were present.

TonyN: You should find out how the drain holes are installed. I can speak from experience that 45 cal hard ball makes a hole about the right size, but the pipe must be prewarmed or it shatters.

In my line of work (civil engineering) 12" ID or 15" ID is usually the minimum when working with culverts (soft conversion is 300 mm or 375 mm). But, when the drain is a french drain, 4" or 6" is not unusual.

TonyN does not state how the flow gets into the pipe.

If it is a french drain, then anything larger than 6" is paying for a premium with not much more benefit. If the inlet of the pipe is open to the atmosphere, then by all means, nothing less than 12" - or 15".

Any tanks.. ground level intake, clean out, discharge etc?

https://www.google.fr/maps/place/Peyrouat,+32250+Montréal/@43.9337709,0.2763223,130m/data=!3m1!1e3!4m5!3m4!1s0x12aa1823331eac53:0xeca3fe791cadf40c!8m2!3d43.933896!4d0.277687?hl=en&authuser=0

This google map shows the property and the houses to be protected from flood run off from the field behind the hedgerow. Fall runs from the west to the point of the hedgerow, and south to the same point. The flood water converges here and floods like a rapid toward the two buildings.

The contractor has proposed a ditch from west to east, and another north to south, along the hedgerows. Where the ditches meet, they have proposed a drainage pipe running south-west to the corner of the grounds, to another ditch. This ditch will run north to south, along the west boundary.

I would imagine that when we have exceptional rain fall, the water run off is pretty heavy, indeed it floods the two buildings.

The contractor has proposed trenching for the pipe (PVC CR4), and then laying it on a bed of stone, then covered with soil. So no filtration from the surface, just collection and directing from the two ditches.

I was hoping the pipe would be at least 300mm, but also wondered if it would block at its entrance, from washed down soil?

There is an existing ditch to the south boundary, which would meet with the west boundary proposed north to south ditch.

In a run going from NW to SE of 640 ft, I get a slope of 43ft....that's about a 1ft drop every 15ft...

If I could work out how to show the ditch and drain proposed route on google maps/earth, I'd post it here for info!

You can right click on the image above, and click copy, then paste the image in paint, make the modifications by making lines color coded, then save the file and post it here using the camera icon at the top of the message window, and selecting the file from your picture files...or you can just make a crude drawing in any drawing program and post it here and I'll flesh it out for you...

1. Green arrows are land fall direction

2. Green lines are existing ditches

3. Blue lines are proposed ditches

4. Red line is proposed pipe

Yes that seems like a workable plan as long as the ditches and pipe are properly constructed and sized....

ref...

https://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=18366.wba

Wow, that is a comprehensive document! I read a few paragraphs, but it was east to get overwhelmed.

I'm waiting for another quote to arrive, the guy had different ideas to the first contractor........

May I say what a great forum this is, and thank you for all the contributors for your help and input.

And to answer the last posters comment about urbanisation above the property. There is next to no chance of that, its a very rural area.

Thanks again and I will post back with the next quote/proposition, for feedback and interest in the project.

That sounds great, try to get all the measurements involved and construction details...thnks

1:15 is almost 7% => rapid flow => significant erosion => possible small diversion canal(s) around property boundaries.

Size the drainage to handle Q₁₀, if not Q_25, year flows, while you still can...

For his voice-of-relevant-experience, ccoop609's suggestion gets a GA from me.

What is the possibility of someone else developing upstream and replace the vegetation with hardened surfaces and thereby increasing the runoff ?

I am not knowledgable about Canadian drainage law. But, every site location I have engineered (Civil) in the USA has requirements that the new runoff peak rate of storm water flow from a developed site has to be mitigated. This means the peak flow rate has to be reduced to a flow level that is usually set by Ordinance. The reduction of peak flow is normally achieved with storm water detention or storm water retention combined with infiltration. The chosen method depends upon the soil characteristics as well as cost. Detention does reduce the peak storm water flow rate. However, detention does not address the increase in total storm water volume. Most municipalities overlook the storm water volume aspect of storm water discharge from developed sites. The changed storm water volume is normally not a big concern anyway. If the storm water discharge onto your land is ultimately passing through your land, then peak flow rate mitigation is the primary and probably only concern. If your land is situated near a "bathtub" feature (i.e. lake, pond, marsh) then volume is definitely more of a concern. However, there are not very many good solutions to reduce storm water volume from developed site. If the soils are conducive to infiltration, that is one method. Only once was I involved with a design to evaporate the additional storm water from a developed site as a means to reduce storm water volume. Crazy expensive. But there is equipment to turn that storm water into steam and discharge it to the atmosphere.

No bathtub situation here, the Peak Flow Rate I wold say is the problem here, which needs mitigation. The soil is clay, so the runoff is rapid without filtration. The newest contractor to visit is proposing open drains (ditches with a bed of gravel, then a 100mm pipe, with slits in it. Backfilled with clean stone to the surface, to allow filtration. Not ideal for across the main lawns, but fine for the hedgerows. I'll wait for the final quote and report back.

I installed a land drain after Mrs S wanted a herb garden. The back yard was like a swamp. 60mm pipe was fine in summer, spring and autumn it was flowing about 75%. The back yard was 30ft below the watershed between the Derwent and the Mersey rivers, it was wet!

The herbs didn’t need watering!