Pond Boss Forums POND CONSTRUCTION Building a dam Overflow Tube: Plastic vs. Steel

I am in the process of constructing a 3 acre Farm pond in Upstate NY. My excavator favors Corrugated Steel culvert tubes for the overflow but I think using Plastic culvert tubes would would be the better way considering the Plastic will not rust and last much longer. I will install a venturi riser tube to draw off the water from lower depths. The downriser/horizontal discharge tube will be 2' diameter and the venturi oversleeve tube will be minimal 3' diameter. Using the formula Area = Pi x R(square) I deterimined that a 3' oversleeve will be needed to feed the 2' downriser. If I use the plastic culvert material I would use double wall (smooth on inside and ribbed on outside). Is 3' diameter plastic culvert an available size? If not what next size up is available? Are Anti-seep collars available to mount on the 2' plastic double wall culvert? Are 2' ells available as well ? Will plastic culvert material in this size stand up to racking stresses of 3 foot thick ice ?

I have 2 ft. platic pipe like you are thinking about and am up in the Catskills. We went through last winter with almost 3 feet thick ice with no issues. I don't have seep collar as my pipe is basically just a spill way that we have a dirt bridge over. Glad I have the 2 ft. pipe as we have seen run-off this year after the tropical storms that nearly filled the pipe.

Our pond is about 1 1/2 acres. You can see photos of it off my home page. Catskill pond designed and built my pond and I think they did a great job.

Check out this site on pipe info:

http://www.hancor.com/pro_cat/contents.html

David - Thank you, that Hancor website was exactly what I needed. A lot of postings mention PVC tubes but I guess when you get up into larger diameters it is HDPE which I guess means High Density Plastic (or Polymer) Extrusion ???.

For anti-seep collars, I found a site with a product that should work for most pipes.
http://www.agridrain.com/pipeproduct.asp?prodtype=104

I believe HDPE is "High Density Poly Ethylene;"
PVC is "Poly Vinyl Chloride."

David,
Yesterday I visisted a local vendor that supplies culverts and highway construction materials.
In describing my design for a venturi style overflow tube for overflowing bottom water using a 3' plastic dual wall culvert as the oversleeve
upriser and 2' plastic dual wall culvert as the downriser. The price quotes I rcvd were;
36" diameter tube = $35.60 per foot ($712.00 for 20' length). 24" = 18.24 per foot ($364.80 for 20' length). I was going to connect a 36" Tee oriented on its side to the bottom of the 36" oversleeve up riser to act as the suction opening. The vendor told me that the Tees are very expensive - almost as much as a 20' length of same size tube ($712)! He said that they cut a round whole in a 36" tube and make a stub insert to accomplish the same thing much cheaper.
He also said that the HD in HDPE meant Heavy Duty. I kinda smiled to myself as I doubt HeavyDuty is a name a chemist would give to classify a plastic. I'm still sticking with High Density something or other.

Haff's, Theo is correct. HDPE stands for high-density polyethylene; a linear non-branched polymer. Low-density polyethylene, LDPE, is a branched, cheaper to make version of PE. You can imagine how a linear collection of polymer molecules can pack easier than a bunch of branched molecules; hence the term "high density". Imagine filling the bed of your pickup truck with all the branches that you just trimmed off of the back yard oak tree, low-density oak (LDO), as compared with loading a cord of oak firewood, high-density oak (HDO) that is well trimmed and cut straight. The firewood will have a greater density and hence weigh more. However, if you really want "heavy duty" go for UHMWPE. This is ultra-high molecular weight linear polyethylene that is a 3 to 6 million molecular weight polymer. These fibers are so strong that they have replaced Kevlar in bullet-proof vests...

Just out of curiosity, why do you need a 2' or 3' drain? I would be willing to bet ten times the cost of the pipe you will never see it run full in your lifetime, I doubt you would ever see a 12 inch pipe copletely full. I used 6 inch PVC pipe for my overflow of less than an acre pond. In reality two 6" pipes will carry twice as much but if you doubled the diameter to 12 inches you can carry 4 times the water. Not to be critical but it seems you are spending a lot of extra cash for rain run off when you should really have adequate free board in your dam to carry a couple days rain anyway. Just my opinion, worth what you paid for it probably.

Joe G

I must have a rather large watershed area upstream of my pond area.

The pond area encompasses an existing intermittant stream that enters my property and then exits. This stream exits my property via a 2' culvert under my driveway. During periods of Spring run off and heavy down pours I have witnessed this culvert fill to 3/4. One two occasions I have witnessed this culvert completely underwater discharging a tremendous amount of water. At first I felt I needed a larger size culvert but my County Soil & Water Conservation Agent felt that a drop tube for same size would handle more water than a horizontal tube. The downriser would have the overflow water dropping, charging the tube with more pressure and increasing the velocity. Therefore a full tube under greater velocity would equal more water than a static pressure horizontal tube.

The stream under normal season dries up towards the end of summer. The last 2 years have been very wet in upstate NY and the stream has not stopped flowing. I would estimate that the stream starts about a mile upstream from the pond site and picks up water the entire route via springs when run-off isnt being added. During the excavation additional springs were disturbed in the pond site which only add to the volume of water.

Joe G

Ref your bet, pls send your check for $3468.00
to 'Save the Children Tsunami Relief' foundation.

Captain, I may be all wet but it seems possible that your county agent might have skipped a few physics classes.
Also, you overlooked giving an address to which Joe could send his check!

Dudley,

The physics sounds logical to me but maybe I am missing something ? I have spent many years on Oil Tankers dealing with fluid dynamics.

The downriser will be coupled to the existing horizontal culvert and be about 8' higher than what I have now to handle the water.

The overflowing water will be dropping 8' and charging the horizontal tube for the water velocity to be greater than the static head velocity it now handles.

I felt that a 90 degree elbow at the interface between the downriser and bottom horizontal discharge tube would add to a turbulent restriction where the flow changes direction so I am going to use a double mitered elbow made out of two 45s instead. This should help the flow to be smoother where it goes around a bend.

Granted the upwelling water coming up the 3' diameter upriser and feeding the 2' diameter downriser wont have the same velocity as the falling water. The 3' upriser outlet will have an open top about 12 inches higher than the downriser inlet so any excess water not upwelling fast enough can crest over the top of the upriser and access the downriser.

Worst case scenarion is that overlow water will be able to fully charge the downriser.. I hope.

As for Joe G's wager, if he goes on the internet he can access the 'Save the Children - Tsunami' web site. I forgot to add the cost of the 3' upriser so that means his check should now be written for 10 times the amount of a 20' section of 3' diameter double wall HDPE tube along with a 20' section of 2' double wall HDPE tube. Ha Ha Ha. Joe's profile says he is an Engineer so maybe he is up on his physics more than I am.