Pond Boss Forums POND CONSTRUCTION Building a dam Drop outlet standpipe Anti Vortex Plate

I am finishing my standpipe and was planning on having a antivortex baffle inside the trash rack/low draw tube. I have seen some designs that have one baffle splitting the intake into two halves and have seen others that split it into four. Does it matter and is one better than the other?

My discharge tube is 6" PVC and the standpipe riser is 8" PVC with a 15" PVC tube surrounding it to cause the water to draw from lower than the surface. The trash rack will be attached to the top of the 15" pipe. The antivortex baffle(s) will span the inside diameter of the 15" which will place them sitting across the top of the 8" riser.

Good question, but I don't have an answer for you.

I ended up making it with 4 sections. If it doesnt seem to work properly I can unbolt half of it and try that. I'll post pictures when I'm done.

Over my head lol.. I have a pipe through my dam when it rains water pours out the backside..

BGK, the purpose of the anti vortex baffles are to prevent a vortex from forming in a vertical stand pipe, similar to a hood on a horizontal overflow pipe or a canopy on an angled overflow pipe. When a vortex does form, it can drastically cut down on the flow rate the pipe can handle since it is basically a big air void taking up space where water should be.

I do not currently have an aeration system and the most oxygenated water is at the waters surface. The reason I have an outer pipe around and slightly above my vertical standpipe is so the water that overflows into the pipe is coming from below the waters surface. Normally a setup like this pulls from much deeper than the 24" depth I am pulling from, but since my pond is mostly excavated, it is better than nothing.

Here is the brass antivotex baffles I made yesterday on the top of the standpipe. Tonight I will cut my 15" outer pipe that will go around the baffle, drill and paint it so I can put it in place this weekend.

Makes sense now.. Cool concept.

The plastic pipe could be slotted for a short ways to prevent any rotation of the anti-vortex baffle and trash rack. Good ideas!

Thanks for the idea. Though it is a tight fit as is it, and there will be bolts around the bottom, pressing into the 8-6" reducer (to hold the bottom centered, I may cut slots about 1/4" deep to drop it in for a little extra insurance.

Drumz, in the construction areas that I've went to, which installed drainage outlets that support habitats for local residential and commercial areas in form of a retention system (an example is City of Upland Colony Crossroads: http://maps.google.com/maps?q=210+and+highland+ave,+upland,+ca&hl=en&ll=34.127419,-117.630765&spn=0.013695,0.01929&sll=37.0625,-95.677068&sspn=53.080379,79.013672&hnear=Highland+Rd,+Upland,+San+Bernardino,+California+91784&t=h&z=16) a similar system was installed to prevent vortexes. The outlets are actually installed at 50°, and some are at 75°, creating a partial backwash pressure to prevent vortex, with a conical cone 2 to 1 ratio of the pipe diameter covering the pipe with 3-in over the pipe itself, with 6 to 8 plate slit-fan to minimize water circular movement. I'll be glad to take the photo of the outlet next time the water drops.

Leo, thanks for the information. I think I understand what you are describing, but would like to see a picture if you do not mind. Here is a picture of the outer pipe, drilled and painted. I need to finish installing the grade316 Stainless hardware and put it in place. The vertical line of bolts are on 1" centers with the highest being at full pool level, that way I can easily tell my water level up to a 20" drop.




Stand pipe.

Drumz...this is really cool. I am having a pond built now, and settled for a traditional system instead of syphon, but I was really keen on the idea of syphon drawing from lower in the water column. I didn't know about this type of concept until now...problem solved! Thanks!

You state that it typically draws from much lower than 24"...how much? Should it be drawn from the deepest point possible?

Is there a reason to have the outer pipe 3" taller than the drain pipe, or could it be even taller?

Lastly, unless I can better understand what Leo is saying, how much for you to make another set of baffles and ship them to VA?

Leo,

I'm very interested in this and hope you can provide a picture or additional explanation.

Thanks a lot for weighing in on this one

Tree Farmer, I saw this design in a state (possibly USDA) pond design hand book, which state escapes me right now. I would have gone deeper with the outer draw pipe, but since my pond is mainly excavated, I was limited by the height of the ground level on the outside of my dam, which is more of a berm. From what I have read, they usually draw from as deep as possible, just keep it high enough off the bottom that any silt build up will not seal the end into the bottom of the pond. The deeper the better since your lower water is usually lower in dissolved oxygen than the water higher up in the column. I went with 3", so that if anything gets plugged or hung up in the bottom it will bypass the low draw design and spill over the top instead of backing up so much to go over the emergency spill way. 3" was a seat of the pants decision, not an engineered one. If it seems to be too much or too little, I can go for a swim and adjust or rebuild it since it is only 24" long.

What sizes of pipe will you be using? I will have to see how much scrap plate brass I have.

I am using 8" pipe, schedule 40. What are the rest of the holes in your outer pipe used for, other than to help determine water level? Perhaps the same question, how do you actually attach the outer pipe to the inner pipe?

The holes at the top are for the antivortex baffle to mount, which will center the outer pipe on the top of the 8" by the way it is notched on the underside. The ring of holes around the bottom are for 3" long 1/4" fully threaded SS bolts, which will have the head on the outside of the pipe, and a nylock nut on the inside to hold them in place. The end will press into the side of my 8"-6" reducer which will hold the bottom of the pipe centered and lock it into place. The bottom ring of bolts will also act as a coarse screen to keep things from getting between the two pipes. The openings are roughly 1.5"X2". I have all the parts needed to finish, I am just lacking the time. I will post pictures when done.

Tree Farmer and Drumz, the outlets are still underwater due to the recent rains. Since it's going to be a while before the water goes down, I can hand drawn the schematic for you. I was there when they installed it. Give me until Friday. I'll be in the field tomorrow, and will be running around like a chicken with its head cut off.

As promised, I had a bit of time before heading into the field.

Picture is attached. Sorry, I'm not the artist in the family. The conical cap is 3" over the tip of the pipe. The pipe that I've seen are between 24" to 36". The cap is made of aluminum, which can also be replaceable. The permanent cap was made of stainless steel. For the stainless steel cap, they also install a 1/2" mesh around the cap's bottom to prerevent debris from entering, since the area is heavily occupied by commercial activities. The aluminum cap outlet is more for the smaller downstream stream ponds designed to direct all flow into the underground CDS unit for further sediment, oil, and debris separation before allowing the water to flow into recharge basins about a mile downstream.

Here is the finished standpipe structure in place. The line of SS bolts running vertical are on 1" centers and will give me water level below full at a quick glance.

Beautiful design! You have got to show us a video in motion as the water level rises and drain. If you have the article for its design somewhere, I would love to get it from you to introduce to the local mom and pop businesses so they can rig this for their sites. They're all DIY people. This can be fabricated using non-ferrous materials.

Nice!! I love the over-engineering for strength, yet the abundance of bottom (trash rack?) bolts may cause it to clog on the bottom....may want to consider adding a trash rack on the top in case it does clog from below or you get a very heavy inflow.

If you look at the sketch all the way at the top of the page, it shows one. I have all the materials, I just need to build it before it gets to the point where it is needed.