SD pipes a hazard?

[Whiskeytown]

A new residential subdivision has some unfenced storm water detention ponds. Inlets and outlets are as follows
6-12" smooth PVC inlets connected to catchbasins
1-18" corrugated HDPE outlet from pond to flow-control manhole
2-18" corrugated HDPE inlets to wetland from pond flow control and overflow structures.
1-30" RCP inlet to pond. (RCP runs about 300' to MH and catchbasins upstream.

Upon final inspection, the municiplity wants to protect against children entering the pipes. The plans call for beveling the pipes (pond bank slopes are about 3:1, and constructing concrete collars with minimum 18" width beyond each side and top of pipe. The subdivision is essentially complete, but the contractor has so far failed to bevel pipe and install collars.
There are no local or state standards that I am aware of. The project engineer has proposed bolting some 1/4" x 2" straps to the concrete collars.
Question: are there guidelines or standards for maximum openings allowable for an facility accessible to children such as this?

 

[RWF7437]

Many jurisdictions require fencing of detention ponds.
Many have details for debris racks which can be placed at inlets, outlets or both.
Machine gun emplacements also discourage children.

 

[RWF7437]

http://www.websters-online-dictionary.org/coreimages/contemporary/USDA_NRCS/2336.jpg

 

[civilperson]

Less than 9" clear opening, (both ways), is considered child proof.

 

[cvg]

in addition to the safety requirements for children, you may need to check your flow capacities and revise your hydraulic analysis to account for the headloss created by the bars, grates and bevels. Not only will the bars obstruct the flow, but they may collect trash which can allow the grate to clog even more. Typically I would assume the grate is 50% clogged for my analysis. You might have less clogging and headloss if you use a vertical headwall instead of a 3:1 bevel. Vertical may also be easier to construct.

 

[Whiskeytown]

Civilperson or anyone else:
If 9" maximum both ways is considered child proof, what would be the maximum one way, as in parallel bars? (I probably should be looking at a building code, I guess.)

 

[cvg]

stair railings are usually about 4 - 6 inches. if bars go just just one way, remember kids can use a stick to bend the bars and get in. for larger pipes, make the grate "redneck proof" - in other words, strong enough so that a redneck with a 12 pack can't get the grate open. Make the bars heavy enough to prevent bending. In other words, a couple of #4 rebar welded down may not be strong enough.

 

[gbam]

Hove you looked at manufacturers for access gates that can be mounted on the inlet? For large culverts our State DOT has a generic standard for a hinged gate specifically for this reason. CVG made a good point, make sure your calcs account for additional headloss. It may be easier to enclose the pond.