Lockable Storm Drain Grates

[jartgo]

I'm looking for any successful design of a lockable grate that would be mounted inside of catch basins and manholes, just beneath the standard grate or manhole cover.

The application is for a prison. The standard grates have been attached to the frames with locking (McGard) bolts, but the owner also wants addtional locking grates inside the basin/manholes as backup in case the bolts are broken from traffic loads.

I'm working on a design constructed from stainless steel rebar, but thought I'd see if anyone in this community has run across this issue before.

Also, does anyone know if a material cost of $1000 per ton for 304 stainless, grade 60, #4 rebar is accurate? By my calculation, this translates to about 35 cents per foot. I'm really just guessing at the $1000 per ton though.

 

[cvg]

cost sounds low to me. when estimating standard (non stainless) rebar, fabricated and installed for structural concrete reinforcing, I usually use between $1 - $2 per pound. I would assume stainless would be considerably more expensive.

 

[tsgrue]

.
I may not be understanding the situation adequately, but could you use grates such as found in sanitary sewer lift stations? I've seen some of these with locks previously.
Seems like you could also have a machine shop modify a lockable solid manhole cover. I've worked with machine shops to make grates on several occasions and it has worked out very well (and cost effective).
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tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation

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