I can't figure out where in the inlet library I would enter the Free Open Area and Weir Perimeter for each inlet type. In GEOPAK this was simple to enter and you could also enter a clogging factor. How do you do this in ORD?
I also tried following the help for how to enter Neenah grates using their K factor charts. Do I understand correctly that I would need a separate entry for each of the cross-slopes from the Neenah book (1%, 2%, 4%, 6%)? Does ORD then interpolate for the actual cross-slope? In GEOPAK I didn't use the Neenah info. I only entered Open Area and Weir Perimeter with a clogging factor where necessary. Has anyone successfully modeled Neenah grates?
Josh
The area and perimeter is computed using the length and width of the grate that you enter in the catalog. The clogging is applied on the prototype.
The clogging is on the prototype under the Inlet Opening section.
For more information about the Road and Site design tools, visit the Road and Site design WIKI at: http://communities.bentley.com/products/road___site_design/w/road_and_site_design__wiki
Also, since I would like to use different clogging factors for a grate that will be used on grade and in a sag location, should I define two different prototypes for situations like this?
here are a few other links to assist
https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/18689/modeling-neenah-grate-inlets
https://communities.bentley.com/products/hydraulics___hydrology/f/haestad-hydraulics-and-hydrology-forum/186816/inlet-type-and-grating/548138#548138
Do I understand correctly that for each Neenah grate I would need to create four catalog entries and prototypes (for all four cross-slopes evaluated in the Neenah literature), and then assign the one with the closest cross-slope to my project's inlets? We have around twelve different inlets that typically use in our organization, which makes this a huge task, and results in a large library / pick list to wade through when building the drainage model.
Hi Josh,I don't generally change the grate width and length dimensions to obtain a target open area. I can use the clogging factor to do that. You can combine the desired open area ratio and clogging factor into one composite factor. Note that this all applies only to inlets in sag locations. Open area, perimeter length, and clogging are irrelevant for on-grade inlets.
If you alter the grate dimensions, then the on-grade interception calculation will not be accurate since frontal flow and side flow are based on those dimensions. FHWA does not recommend a clogging factor for on-grade inlets unless local conditions warrant it. However, perhaps your client requires it. If so, then maybe you'll need to create separate inlet entries as you suggested. To account for clogging of on-grade inlets, you will need to reduce the grate dimensions. The clogging factor will not apply to your on-grade inlets since it only reduces open area which has no impact on the on-grade calculations.
Karl Dauber, PEAdvance ConsultingLaurens County, SCkarldauber@advconsult.netwww.advconsult.netwww.linkedin.com/in/karldauber
Thank you Karl. That is the best answer and information I have seen so far. I'll keep plugging away at setting up our standards.