How to find an engineer to inspect a dam wall

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retired recently
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How to find an engineer to inspect a dam wall

Post by retired recently » Wed Apr 17, 2019 7:03 pm

I am interested in some land that has a small pond. There is a house about 50 yards directly in the path of any water if the dam were to break. The real estate agent indicated the pond had been there for many years and was surely fine. I did a small amount of "google research" and learned there is quite a bit to building a dam. I guess it is about an acre pond and the real estate agent indicated it was 20 feet deep but I doubt it is that deep. The agent doubted the owner had any documentation but said he would ask...

If I were to go forward with this who would I get to inspect the dam. The land is located in western NC. Presumably I could start at the county offices and find someone to give recommendations? Any idea how much this might cost?

mortfree
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Re: How to find an engineer to inspect a dam wall

Post by mortfree » Wed Apr 17, 2019 7:08 pm

I can’t answer your question about the dam inspection but...

Remember the key sign to knowing when a real estate agent is lying...

Army Corp of engineers???

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whodidntante
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Re: How to find an engineer to inspect a dam wall

Post by whodidntante » Wed Apr 17, 2019 7:16 pm

Dam engineer?

shunkman
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Re: How to find an engineer to inspect a dam wall

Post by shunkman » Wed Apr 17, 2019 7:17 pm

Does the County even know that this dam exists? In many areas, private lakes with dams must be drained each year so a costly safety inspection can be performed. The inspection is paid for by the dam owner. This could be a huge liability.

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fortfun
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Re: How to find an engineer to inspect a dam wall

Post by fortfun » Wed Apr 17, 2019 7:29 pm

Google Civil Engineer and your city/county. Often, Civil Engineers also provide land surveying. So you could look up land surveyors also and see if they provide civil engineering services too. If the assessment is done correctly, I suspect it could be very expensive (i.e. drilling core samples, etc.)
Last edited by fortfun on Wed Apr 17, 2019 7:31 pm, edited 1 time in total.

scottgekko
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Re: How to find an engineer to inspect a dam wall

Post by scottgekko » Wed Apr 17, 2019 7:30 pm

The dam phone book? Sorry, couldn't resist....

Millennial
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Re: How to find an engineer to inspect a dam wall

Post by Millennial » Wed Apr 17, 2019 7:32 pm

Call civil and geotechnical engineers in your area. This is a little specialized so you might not get the right firm on your first try, but if they say it's not in their skill set ask for a referral.

Separately, research (and ask the engineer) if your state has an Office of Dam Safety or something similar. In the Northeast, most states require periodic inspection and reporting of dam condition. How costly this is may depend on the dam's hazard classification, which will be determined by the volume of water and what's in it's path. I'm not sure how much of this applies in NC.

gmc4h232
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Re: How to find an engineer to inspect a dam wall

Post by gmc4h232 » Wed Apr 17, 2019 7:49 pm

Make sure the dam requires an inspection. Not sure about NC, but in VA the last time i checked agricultural ponds, or dams that impound less than a certain amount of acre-ft of water dont require regular inspections.

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Re: How to find an engineer to inspect a dam wall

Post by retired recently » Wed Apr 17, 2019 7:50 pm

Thanks very much for the replies.

I think the main issue is that there is a residence in the direct path which is what really drew my attention to it. From the little bit of online reading I did, there was discussion on ensuring no trees growing on the dam and also ensuring no rodents. I did not notice any rodent holes but it is a wooded area and I think there were some growing on the dam itself but cannot recall.

Certainly some work to be done. If I move forward with it I will circle back with what is found.

Thanks again.

megabad
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Re: How to find an engineer to inspect a dam wall

Post by megabad » Wed Apr 17, 2019 8:39 pm

retired recently wrote:
Wed Apr 17, 2019 7:50 pm
I think the main issue is that there is a residence in the direct path which is what really drew my attention to it.
I think you are wise to focus on it. In my opinion, I would call a house positioned in such a way a "future boat".

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Re: How to find an engineer to inspect a dam wall

Post by stan1 » Wed Apr 17, 2019 8:49 pm

Hydrological engineer (specialized civil engineer)

Mike Scott
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Re: How to find an engineer to inspect a dam wall

Post by Mike Scott » Wed Apr 17, 2019 8:50 pm

In many rural areas there are no or few regulations. I have a similar structure in my front yard and no one knows or cares.... but there is not a house immediately downstream. That would be a concern whether there are regulations or not.

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Re: How to find an engineer to inspect a dam wall

Post by Teague » Wed Apr 17, 2019 9:59 pm

retired recently wrote:
Wed Apr 17, 2019 7:03 pm
The real estate agent indicated the pond had been there for many years and was surely fine....
These dams were also there for many years, until some of them weren't:
https://damsafety.org/dam-failures

"From January 2005 through June 2013, state dam safety programs reported 173 dam failures and 587 "incidents" - episodes that, without intervention, would likely have resulted in dam failure."
I'd guess smaller structures like yours wouldn't even make that list.
The agent doubted the owner had any documentation but said he would ask...
That just sounds really weird. So the owner is telling the agent something like "Dam? What dam? Oh, gee, how did that thing get there?"
Semper Augustus

JGoneRiding
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Re: How to find an engineer to inspect a dam wall

Post by JGoneRiding » Wed Apr 17, 2019 10:19 pm

I have a small pond. The pond you describe is a small lake! I would be concerned esp if there is no place for the water to go and or no way to control inflow.

My pond's is about 100feet by 60 feet and controlled by irrigation inflow. It's also designed to run around the house if overflow (this I found out by accident) and only 4 feet deep. It could still cause an issue if not careful

123
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Re: How to find an engineer to inspect a dam wall

Post by 123 » Thu Apr 18, 2019 12:25 am

The mention that the pond/dam has been there "many years" would make me question it all the more. "Many years" ago the expectations for construction of artificial ponds/dams were undoubtedly quite different than what we expect today. Is the pond/dam unique to the neighborhood or are there others all over the area? What water source feeds the pond? What/where are the outlets for the pond?

An acre of water is a lot to manage if gravity gets its way.

The satellite view on Google Maps might give you some insight into the situation. Another site you might find helpful is https://www.historicaerials.com/ it has historic aerial photos of many areas as well as topological maps that may give you the "lay of the land". You may be able to find out approximately when the pond was added by the vintage of the first map that it appears on.
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Re: How to find an engineer to inspect a dam wall

Post by retired recently » Thu Apr 18, 2019 4:21 am

Two small springs feed the pond/lake. There is only one way for the water to leave, via a pipe that runs through the dam.

I suspect it is only a few feet deep but the realtor claimed it was 24 feet deep, if so I guess it would be a lake, in any case a lot of water.

This area is somewhat remote so no idea if there are many other similar ponds. Beautiful piece of property...it is a shame the pond and house are situated so near one another. The pond also seems to have quite a bit of growth on it, if all works out I need to figure out how to get some of the algae, etc out of there. Supposedly it was stocked in years past and the realtor claimed he and his son caught quite a few bass/crappie recently.

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Re: How to find an engineer to inspect a dam wall

Post by smitcat » Thu Apr 18, 2019 7:53 am

retired recently wrote:
Thu Apr 18, 2019 4:21 am
Two small springs feed the pond/lake. There is only one way for the water to leave, via a pipe that runs through the dam.

I suspect it is only a few feet deep but the realtor claimed it was 24 feet deep, if so I guess it would be a lake, in any case a lot of water.

This area is somewhat remote so no idea if there are many other similar ponds. Beautiful piece of property...it is a shame the pond and house are situated so near one another. The pond also seems to have quite a bit of growth on it, if all works out I need to figure out how to get some of the algae, etc out of there. Supposedly it was stocked in years past and the realtor claimed he and his son caught quite a few bass/crappie recently.
My best thoughts are that any time or money spent should go towards moving or rebuilding the home to a location that is not subject to water or flooding. That should be your best move.

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Re: How to find an engineer to inspect a dam wall

Post by Sandtrap » Thu Apr 18, 2019 8:01 am

It sounds like the type of property that's best to stay away from to avoid future liabilities. While things may be fixed now, what about when water levels are very high due to "100 year rains" flooding, etc.
Sometimes it's good to listen to the "little voice". :shock:

I once bought a property to develop at a great price. 180 degree ocean views. Mountainside lot. Beautiful surroundings. But, something never felt right. Yep. From the day I bought it until the day I sold it after pouring in big money over time. There were always drainage issues. Fortunately, I recovered my investment.
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Ping Pong
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Re: How to find an engineer to inspect a dam wall

Post by Ping Pong » Thu Apr 18, 2019 8:15 am

How many feet is the floor of the house below the water surface of the pond when there is water flowing out the pipe?

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lthenderson
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Re: How to find an engineer to inspect a dam wall

Post by lthenderson » Thu Apr 18, 2019 8:24 am

I grew up on a farm with probably 20 or 30 such ponds with earthen dams. Not a one of them required any sort of inspection to build and I would probably guess you will not have any luck finding anyone to inspect it. Even if you did, there really isn't anything someone looking on the outside layer of a dam can tell except that yes a dam is there. The structural water retaining part is the interior part and only the dam builder would know anything about it.

You do want to keep tree roots and burrowing rodents from pond dams as they can do damage. In all my years however, I've never seen a catastrophic water release from a small earthen pond dam. The water pressures just aren't there for shallow ponds. They generally develop small leaks and have pretty controlled water releases. You said the house downstream is directly in the path of the water but I'm guessing this can't be the case since you have two springs flowing into the pond and presumably water flowing out through the overflow pipe right now. I'm guessing it would only be in the path of a catastrophic release which is very unlikely to happen.

I wouldn't let the pond stop you from purchasing the property. Just make sure your liability policy would cover damage caused by your pond, stock it with some native fish and enjoy it.

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Re: How to find an engineer to inspect a dam wall

Post by fourniks » Thu Apr 18, 2019 8:34 am

Many states regulate dams. In my state (MO), there are categories of dams, such as "high-hazard" dams, that require initial siting and investigation by a registered geologist. The hazard classification has to do with the height if the dam (measured from the toe) along with the presence of dwellings downgradient from the outfall. If your state has similar laws and your dam meets the definition, there would be documentation with the State dam safety program. If not, that State program, or something similar, should be able to provide some things to look for.

I doubt yours falls into that category, but you still need to find someone to assess (if not doing so yourself). Without the availability of as-built construction documents, a geologist or engineer could perform a visual inspection to look at things like: erosion of the earthen dam materials, erosion around the culvert/outfall, condition of the effluent intake (clear of debris/trees/woody material?), is the dam clear of woody vegetation (trees), evidence of overtopping, and is there any evidence of seepage/underseepage, especially at the toe of the dam.

Engineering companies may be able to perform an non-intrusive geophysical assessment of the dam centerline to identify any potential shortcomings.

edited to include looking for visual evidence of overtopping

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Re: How to find an engineer to inspect a dam wall

Post by researcher » Thu Apr 18, 2019 8:53 am

shunkman wrote:
Wed Apr 17, 2019 7:17 pm
In many areas, private lakes with dams must be drained each year so a costly safety inspection can be performed. The inspection is paid for by the dam owner. This could be a huge liability.
Can you name a state that requires private lakes to be drained & inspected every year?
I've never heard of such a thing.

Any state outside of the southwest has tens of thousands of private ponds/lakes.
It is simply not possible to do what you claim.

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Re: How to find an engineer to inspect a dam wall

Post by WWV » Thu Apr 18, 2019 9:14 am

You might want to look at the FEMA flood zone map just to get a rough idea of where things currently.

www.fema.gov/flood-mapping-products
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Re: How to find an engineer to inspect a dam wall

Post by researcher » Thu Apr 18, 2019 9:18 am

retired recently wrote:
Thu Apr 18, 2019 4:21 am
Two small springs feed the pond/lake. There is only one way for the water to leave, via a pipe that runs through the dam.

I suspect it is only a few feet deep but the realtor claimed it was 24 feet deep, if so I guess it would be a lake, in any case a lot of water.

This area is somewhat remote so no idea if there are many other similar ponds. Beautiful piece of property...it is a shame the pond and house are situated so near one another. The pond also seems to have quite a bit of growth on it, if all works out I need to figure out how to get some of the algae, etc out of there. Supposedly it was stocked in years past and the realtor claimed he and his son caught quite a few bass/crappie recently.
You are getting some really bad information/advice in this thread.

There are thousands upon thousands of ponds like yours in that area of the country.
I would lose zero sleep over the chance of a catastrophic dam failure on a small spring fed pond.
There are hundreds of other issues that are far more likely...being struck by lightning, attacked by a bear, hit by a falling tree.
If it makes you feel better, call the county extension agent or a pond builder to come have a look and assuage your concerns.

Where does that discharge pipe (and the water) go? It presumably flows into a creek/ravine/ect, correct?

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Re: How to find an engineer to inspect a dam wall

Post by retired recently » Tue Apr 23, 2019 4:26 pm

So I went back to the property by myself to spend more time. It is almost 200 acres and I did not spend much time looking at the dam when I was with the realtor. I took a kayak and the depth of the pond (about an acre) is no more than 12 feet at the deepest part. The land continues to fall away from the dam and the nearby home is actually up a hill so I do not think there is any possibility of damaging the home if the dam were to fail. This was not apparent on my first visit.

The dam is not currently classified as high hazard and hopefully this is not just an oversight. I have agreed to split the cost for a dam engineer to inspect the dam. Assuming there are no issues I plan to buy the property.

It is a really nice piece of land and I hope there are no issues.

Thanks again for all the feedback!

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Re: How to find an engineer to inspect a dam wall

Post by Glockenspiel » Tue Apr 23, 2019 8:17 pm

You need a dam safety hazard classification and I would also want a dam inspection report put together on it. Is this just an agricultural dam? I assume it’s private. I’m a civil water resources engineer so I work pretty closely with people who do this. I would google your closest large city and “geotechnical engineer”.

The geotechnical engineer should give you a price to put together a full report and inspection of the entire dam. I would also want soil borings at a few locations on the dam and the geotechnical engineer would provide those and do seepage and slope stability analysis.

A water resources engineer would be able to contribute to a report discussing the dam’s hazard classification and if there are property damage or if lives would be endangered by a dam breach.

The geotechnical engineer should be able to either work with a subcontractor to get some input on the safety classification, as they focus on the soil stability aspects instead.

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Re: How to find an engineer to inspect a dam wall

Post by Glockenspiel » Tue Apr 23, 2019 8:50 pm

Also, the safety (hazard classification) of the dam depends mosty on its height, the elevation of the water, and the elevation of any buildings or property downstream of the dam. You want the dam to be free of trees growing on it, large rodent holes, etc., as those could cause water seepage through the dam, and once water starts sleeping through, it’s harder to stop a dam breach. If it’s a small embankment and the water isn’t too deep against the dam, I wouldn’t be quite as worried.

3feetpete
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Re: How to find an engineer to inspect a dam wall

Post by 3feetpete » Wed Apr 24, 2019 6:35 am

I worked in the dam construction and repair industry for many years. One of the best dam engineering companies in the country has offices in your state. Contact Schnabel Engineering.

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