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#5815 - 06/26/06 01:22 PM Dam pipe vs. spillway
cwooten Offline

Registered: 02/02/06
Posts: 50
Loc: Oklahoma City
I am currently half through digging out a 1.5 acre pond above a 2.5 acre pond that I just drained to dig out. My local NRCS person has his opinions but I would like others as well. I have done alot of reading online as well as on pond boss and have now read enough to be confused and undecided. I called a local contractor today to look at my situation and give his opinion.

My questions are:

Do I want a drainpipe or just a spillway? Do I want a bottom drain or top drain with/without a standpipe. Do I want a siphon system? My NRCS guy frowned on a bottom drain.

Could someone tell me a little more about the PVC and is that the best option?

Thanks, Craig

#5816 - 06/26/06 02:18 PM Re: Dam pipe vs. spillway
Brettski Offline
Field Correspondent

Registered: 10/07/05
Posts: 6916
Loc: Illinois
(unless you have already been there...)start with this thread that I started: Drain & valve thread
Your question is very current for me; I just finished installing a PVC pipe drain and valve a week ago. You will get pro's and con's from this forum about drain pipes until the cows come home. I am in no position to make a recommendation...too new for me (but my decision is obvious).
I will point out one thing, tho, that I believe many people overlook when dealing with PVC pipe. Schedule 40 guarantees certain dimensions and tolerances. It does not guarantee pressure rating. The ASTM specification will indicate the pressure rating. Alot of the PVC pipe that comes from the home centers is DWV rated. It may not meet the higher pressure quality rating. My pipes were printed with "DWV", but they also included the ASTM spec's (3 of them). When I contacted the manufacturer, Charlotte Pipe, their tech guru told me that the 3 diff ASTM spec's cover: 1) DWV 2)Pressure 160 psi 3) Well casing In other words, this pipe will meet all 3 ASTM standards for each prescribed application. He noted that some pipe will not...can vary from production lot to lot, mfgr to mfgr. The fittings are the same.

#5817 - 06/26/06 07:05 PM Re: Dam pipe vs. spillway
Dave Davidson1 Offline

Registered: 01/04/06
Posts: 13657
Loc: Hurst & Bowie, Texas
Craig, I'm not an expert but I like the idea of a PVC drain. I have a 12 inch PVC pipe with an anti seep collar. I've only needed it once and it handled a lot of water that I would not have wanted going over the spillway. The natural ground of a spillway can be tough to replace.

I consider a spillway as a real emergency (100 yr. flood) relief system. Most people do but you will find some pretty intelligent people here who disagree with me.

Did the NRCS guy give any reason for not liking the idea of bringing water off the bottom? That stuff is usually "dead" and is the best stuff to get rid of.
It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP

#5818 - 06/27/06 10:54 AM Re: Dam pipe vs. spillway
Edward P. Eitel Offline

Registered: 05/11/04
Posts: 234
Loc: Lusk, Wyoming

Personally, I like the idea of a bottom drain (i.e. Agri-Drain type System).

I also like top drains, or “shotgun tubes” as they are affectionately referred to around here.

I have also seen some nice systems that run perennial water through the earth spillway. (Not generally recommended around here because of our very erosive soils.)

I do like PVC pipe as a principal spillway, HOWEVER:
Please paint the exposed surfaces of PVC pipe with a good outdoor type paint. PVC material has a very low tolerance for ultra-violet light (sunlight). I believe we have all seen yellowing PVC pipe lying outside. It eventually becomes very brittle if exposed to sunlight and breaks easily. A good paint cover will extend the life of exposed pipe surfaces for a long time.


#5819 - 06/27/06 11:27 AM Re: Dam pipe vs. spillway
Alligator Offline

Registered: 03/30/05
Posts: 821
Loc: East Texas

I recommend having both; a pipe drain for normal fill level runoff + an emergency spillway for the unusually large rain event.

I'm not sure why your NRCS guy would frown on a bottom draw system other than in my dealings with pond folks - they don’t recommend what they don’t know. The advantage of a bottom draw system is to remove oxygen depleted water + the installation puts the hole through your dam at the water level vs. the bottom of your dam which is much easier to install and get to if there is a problem, IMO.

- Smoke 'em if you got 'em

#5820 - 06/27/06 11:48 AM Re: Dam pipe vs. spillway
Meadowlark Offline

Registered: 03/09/04
Posts: 3075
Loc: East Texas

I'm probably a minority of one on this question on this Forum...but you asked to hear other opinions.

Whatever you decide, do have emergency spillway(s). They don't cost much of anything and can provide great insurance.

We usually get 100 year floods about twice a year in my area. ;\) Last year only had one, however. I have 4 ponds of varying sizes with more on the way. None have anything through or in the dam except for good clay. None have ever had a single problem with natural spillways. One pond is an estimated 75 years old. The spillways are as functional today as when it was built....and with virtually no maintenance. Now, I can't say the same about folks I know who have drain pipes.

Perhaps today's materials and installation methods have been perfected to where drains don't fail...I just don't trust them and don't see spending $8000 or more for one.

The argument about removing bottom water seems valid, but a siphon system could do that also. In addition, I would much rather spend my money on the best aeration system I could get, rather than on a bottom drain.

I'm pleasantly surprised to see a NRCS person with similar thoughts....they seem to always push drain systems. Look around at your neighbors, talk to them...both with and without bottom drains. I'd put a lot of weight on their experience. Some areas are not suitable to natural spillways either as emergency or main line. That certainly is a consideration.

I'm just offering another opinion, which you requested. Certainly not interested in another emotional discussion of same. Gather the facts and make an informed decision.

#5821 - 06/27/06 12:35 PM Re: Dam pipe vs. spillway
dave in el dorado ca Offline

Registered: 04/26/06
Posts: 3261
Loc: el dorado ca
Originally posted by Meadowlark:
The argument about removing bottom water seems valid, but a siphon system could do that also. In addition, I would much rather spend my money on the best aeration system I could get, rather than on a bottom drain.

........ Gather the facts and make an informed decision.
howdy cw and dittos to meadowlark. when renovating my pond i had the opportunity to consider (install) additional drain systems (other than the spillway) and opted to stay w/ just the spillway which has done a bang up job for close to 40 years. the downstream ranch pond (5 ac.) has only a spillway and is reportedly over 100 yr. old. the ranch family settled the area in 1850 and built the pond around turn of century.

this is not to say that internal drain systems whether bottom type or drop tube are not useful, wise to have, and provide good control of your water, just that in my case, the spillway works well enough for my needs, and i needed/wanted to save my money for other things such as aeration. if your objectives include periodic draining for weed control, fish management or whatever else, obviously you'll need that type of control.

meadowlark, since 1981 here in Nor Cal, we've had at least 5 years of "100-yr" precip events. this last wet season (>55-inches) was one of them. the main trick for successfull spillways is to determine your worst case scenario flows (best by watershed calcs w/ good slop factor) and build accordingly.
GSF are people too!

#5822 - 06/27/06 02:04 PM Re: Dam pipe vs. spillway
Eastland Offline

Registered: 04/20/03
Posts: 1039
Loc: Dallas TX
I'm also with Meadowlark \:\) I would build a spillway with 36" freeboard everytime and save my hard earned $$$ for forage and/or feed, aeration, and possibly a supplemental well.

One of our ponds was built in 56 and water goes over the spillway every Spring...it has good clay and looks to stand another 50 years.

#5823 - 07/06/06 10:37 AM Re: Dam pipe vs. spillway
cwooten Offline

Registered: 02/02/06
Posts: 50
Loc: Oklahoma City
Thanks for all your inputs. I have been busy digging. I received a catalog from pond damn piping in Macon. I am researching their system and would like to talk to some of their references. I think what I may do is repair the spillway where I trenched it to drain the pond and decide later if I want to put in a siphon system. The nice thing about that is it goes through the top of the dam and it is cheaper than metal.


#5824 - 07/06/06 02:18 PM Re: Dam pipe vs. spillway
eddie_walker Offline

Registered: 11/23/05
Posts: 773
Loc: Just North of Tyler, Texas
I'm relying on an overflow for my primary drain. It will be concrete on virgin soil and drain off over bermuda grass on a 2 to 3 degree slope over an area 30 feet wide. The overflow will be 20 feet wide and two feet tall. After that, I'm in trouble.

To help manage my pond I put in a bottom drain. I used six inch PVC with a butterfly valve. (Thanks Brettski).

The drain will be six inches lower than the overflow to handle light duty rains, but be pretty much useless on heavy rains.

The biggest reason for putting it in is that I can adjust my water level by opening the valve. The siphon system seemed like more effort than I wanted to deal with.

Two reasons really influenced my desire for a drain.

One is to lower the water level to kill shorline vegitation. I'll be able to drop the water level several feet and let the plants die, then mow them down.

Second reason is that if I'm expecting a severe storm, tropical storm or maybe a hurricane, I can drop the water level before it gets here. Hurricane Rita was supposed to drop over 20 inches of rain in my area. It didn't happen, but I realize that one day it could.

This is also why I'm using concrete for my spillway. For a few hundred bucks, I'll never have to worry about erossion. This will also support a bridge over the spillway that I'll build sometime down the road.

Lake Marabou http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=139488&fpart=1

It's not how many ideas you have, but how many you make happen.

3/4 and 4 acre ponds.


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