Bill,

We were faced this problem some time back with surcharged inlets, we found it is very hard to get good results with surcharged inlets, took us atleast one full month checking all the options and checking data of such a big project again and again. At last we found only way to solve the problem is add some storage points to delay the peak and see what's happening, then it worked, from that it seems like SWMM may not handle that many surcharged inlets. I suggest you too add storage and see what happens. Your problem reminding me of all my difficulties and research with different SWMM interfaces and version.

Don't know how much I helped you, Good Luck

Srinivas Ravulaparthi P.E.
sravu@TAPANAM.COM