Spillway incorporated into driveway

[JimMorrissey]

Looking for some input from folks......I have an area that I'm cleaning out for a pond on my property. It's a lowland that has been bridged. The bridge section is rock and road base material built up to create a driveway from the main road to our garage / house. Just imagine a dirt and rock road built up across a low area with culverts at the base. The sides are steep in both directions. My plan is to seal the culverts at the base of the road and install something (yet unknown spillway) at a higher level creating a pond on the sealed side. I'll use this pond to skate in the winter and irrigate the lawns/gardens in the summer.

Question is: What would be the best way to drain the water? I'd need it to be strong enough to withstand the weight of a cement truck or two and regular use as a driveway. One cement truck would do the damage of 1000 passenger cars, but I wanted to mention it's primary use. Appreciate any ideas.....

I don't want to dig down too deep and install another culvert because the pond would be too shallow at that point. A culvert would need to be buried deep to withstand the weight. Also need to consider that I may pave the drive at some point. Could I use a series of large loose rock to form a wide, super strong spillway? Would it allow enough flow in a rare 20 year rain event without spilling over the main road and washing away the drive? Could I pour a concrete spillway, then cover it with pressure treated 2x6? Not likely strong enough for trucks and what about future paving?

 

[jbooth]

How about instead plugging your present culvert build a cement structure in front of the present culvert and let the water drop down to go through the culvert. Might be some issues of sealing the structure to the present culvert. You could incorporate some removable boards in the structure to control your water level. I live in Kansas and we are blessed with constant drought interrupted only by intense flooding. The main problems with any spillway is to much fall/drop causing erosion. Does your present culvert always handle the flow? If not you might want to add additional culverts at higher elevations. Ice expansion might be a problem and move your stucture. At any rate the structure would need to be constructed to meet the needs of your invironment.

Jim Booth

 

[MarkV]

Jim you have me wondering is your drive made of rock and road base will seal well enough to be used as a dam. Around here pond dams are built with clay and some of those have problems with leaks when the right type of clay is not found on site.

MarkV

 

[JimMorrissey]

How about instead plugging your present culvert build a cement structure in front of the present culvert and let the water drop down to go through the culvert. Might be some issues of sealing the structure to the present culvert. You could incorporate some removable boards in the structure to control your water level. I live in Kansas and we are blessed with constant drought interrupted only by intense flooding. The main problems with any spillway is to much fall/drop causing erosion. Does your present culvert always handle the flow? If not you might want to add additional culverts at higher elevations. Ice expansion might be a problem and move your stucture. At any rate the structure would need to be constructed to meet the needs of your invironment.

Jim Booth

Jim.....Good thought on the cement down drop and the potential ice action. I will put some more thought into that concept and proper sealing. Would think a 5 gallon pail of hydraulic cement should take care of any union issues.

 

[JimMorrissey]

Jim you have me wondering is your drive made of rock and road base will seal well enough to be used as a dam. Around here pond dams are built with clay and some of those have problems with leaks when the right type of clay is not found on site.

MarkV

Mark, I had it filled last year for about a month with a temporary plug to get a feel for how big the pond would be. There were no stabilization issues as the road is super compacted and it's 10'-12' wide and 6' high. I just let the water spill over the top of the road and run down the other side for a bit. I suppose there is the possibility of water eventually leaking through over years and destabilizing the mass. I've looked into this super expansive clay product the you add to ponds to help seal....Believe the name is Bentonite clay or something like that. Big bucks to have it shipped though.

Wonder if I should consider a rubber liner now and cover it with crushed stone for looks.

 

[dodge man]

The liner might not be a bad idea. How do you seal the ends? Bury them into the ground? Having water against it for a long period of time might cause leaks. A common spill way is just a vertical pipe with an elbow that leads to a horizontal pipe. The problem is you have to dig that in through your roadway. It is common on larger dams to have an emergency spill way. It is just a low area, usually towards the end of the dam, that lets water flow over it, without washing out the dam.

 

[JimMorrissey]

I think I'm going to abandon the old converts and just lay a new set of (3) 12" pipes in parallel. Then I'll have some 1-1/2 crushed stone material delivered to go over the top. Might dig down a bit to allow for more crushed stone on top. Thought about pouring concrete on top on the three culverts, but don't think it's necessary if I can get 24" of base material on top. Any suggestions on minimum culvert depth ?

Just wanted to add that this plan will keep me from having to deal with ice action on the downspout.....as Jim Booth pointed out.