Pipe Surcharge
Pipe Surcharge
(OP)
Hi,
We recently recieved a review comment requesting that we install watertight joints on a RCP storm drain line due to the fact that the HGL showed that the pipe was surcharged.
This particular line is the most upstream segment in the system and the surcharge is due to inlet control.
My question is does this make sense? Is an inlet controlled pipe under pressure? I wouldn't think so due to the fact that inlet controlled pipes do not flow full.
Also we had this same request on some of the downstream lines where the pipe was surcharged by somewhere in the range of 0.1'-0.3'. I would think the pressure on these lines would be minimal. Does it make sense to install watertight joints? If not is there a reference that would help me make that argument?
Thanks
We recently recieved a review comment requesting that we install watertight joints on a RCP storm drain line due to the fact that the HGL showed that the pipe was surcharged.
This particular line is the most upstream segment in the system and the surcharge is due to inlet control.
My question is does this make sense? Is an inlet controlled pipe under pressure? I wouldn't think so due to the fact that inlet controlled pipes do not flow full.
Also we had this same request on some of the downstream lines where the pipe was surcharged by somewhere in the range of 0.1'-0.3'. I would think the pressure on these lines would be minimal. Does it make sense to install watertight joints? If not is there a reference that would help me make that argument?
Thanks





RE: Pipe Surcharge
RE: Pipe Surcharge
RE: Pipe Surcharge
CVG, I'm just curious, why should they be gasketed if there is high ground water? Infiltration?
RE: Pipe Surcharge
However that may be;
remember that you have designed this pipe for only one, or a few, of many possible storms and that the probable error in your calculations is on the order of plus or minus 50%, if you're very careful.
remember that the cost difference between rubber gasketed and tongue and groove joints is probably minimal compared to the total cost of your project
remember that infiltration or exfiltration and possible piping or hydraulic failure are real concerns to the agency who has to maintain this storm drain for the rest of its useful life.
a few dollars spent to guard against these things seems a small price to pay, to some of us .
good luck
RE: Pipe Surcharge
soil tight joints will prevent most piping failure. However, this can also be done by wrapping with filter fabric.
gaskets will prevent infiltration which can draw down the groundwater. Dept of Water Resources will not like the idea of your storm drain siphoning off groundwater to the nearest stream. Local agencies where I currently practice routinely require rubber gasketed concrete pipe. The pipe costs more, however installation may be quicker than tongue and groove which require mortar to seal the joints. Leak resistance is also superior for gaskets.