Covering a frustrating manhole 2

[Kozzybear]

I am currently having trouble covering a manhole, cue to all these extra little things I have to worry about. I have been racking my brain for a solution and have looked through way to many catalogs. Here are all the things I am worrying about:

1. The hole has to be 48"x30"
2. The hole is in a truck yard and must be able to hold the weight of half a 34,000 lb axle distributed over a 10"x20" surface on the grate
(This one is the kicker)
3. In this manhole is 2 subpumps, and the truck yard is covered in gravel, so if you go with the option of a grate, then the openings can be no larger than 1/2" without risking destorying the pump.

If anyone has ever encountered this before, I would love some input. I have looked at U.S. Foundry and McNichols for grates, as well as a lot of hatch door companies.

 

[agua84]

Neenah Foundry is a longstanding name. R-6665? May need to check with mfg. for loading data. Does it need to be opened much? How about a hatch overlaid by a heavy steel plate. I would stay away from a grate.

 

[cvg]

NEENAH R-3498 SERIES, comes in 48 x 48 gray iron with spring assist hatch and is proof tested to 200,000 lbs

 

[bridgebuster]

I had something similar two years ago; had to cover an 8' diameter manhole; HS20 truck; we used a 12'x12' slab, in the middle there was a 4'x6' Bilco hatch to access the sump pumps.

 

[Kozzybear]

Hey, thanks everyone for the input... decided to just throw in a junction box and get the pumps away from the yard, making the hatch a little less heavy duty. It actually ended up being a little cheaper. Definitely going to keep Neenah in mind for future projects though.