ORD Drainage & Utilities - Questions and Observations (ORD v10.16.2.267)

Our organization is just starting to use the ORD Drainage & Utilities package for storm sewer design. We have laid out a storm sewer system and performed an analysis on the system using the software. We also used calculations in our organization's design manual to verify the software's design outputs. From that comparison we came up with the following questions and observations. All the following information is based on drainage analysis using the rational method.

  • Is it possible to edit an individual inlet to set it's efficiency to 0 or to artificially make the software think the inlet is plugged? When analyzing the 50-year recurrence interval storm we often assume the sag inlet is plugged to determine whether the flanking inlets can handle the 50-year storm gutter flows acceptably. We tried to do this by "turning off" the sag inlet in the active topology for the 50-year storm analysis we created, but the software generates an error that it cannot compute the scenario. Any suggestions on how to best analyze this scenario without having to create a second storm sewer layout where the sag inlet is placed as a different type of node, like say a manhole, instead of an inlet? Thanks to another user this question has been answered. We were able to successfully change the inlet type to a percent capture and then set the inlet efficiency to 0.1. Running the analysis again the results came back as if that inlet were plugged and non functional. We tried setting the capture efficiency to zero, but the software would not compute.
  • There seems to be a flow discontinuity in how the software calculates flow in the gutters vs how the software calculates flow in the pipes. This is difficult to explain, but if you sum for example the flow from an upstream pipe and the intercepted flow at an inlet, then that some does not equal the flow in the pipe leaving that inlet. Sometimes the flow in the downstream pipe is higher and sometimes it is lower. Any insight into what might be occurring?
  • After performing an analysis the software appears to draw a trapezoidal type shape that we believe is meant to graphically represent the spread in the gutter. While this shape is sometimes drawn correctly and shows the spread in the roadway, the software sometimes shows this spread going up onto the backslope behind the inlets. Is this normal or is this indicative of something we've placed incorrectly? Reviewing the reports from the analysis the other results seem to make sense except for the graphical representation of the spread. Any insights into why the software is generating a graphical representation of the spread in an incorrect orientation?
  • When comparing the results from the software's analysis we noticed the software is determining inlet efficiencies that are much lower than those we get when we calculate the efficiency following the procedures in our organizations design manual. We've reviewed the inlet's properties and utility properties and we've also reviewed the inlets in the catalogue. Everything seems to match our standard plans for the inlets we are using. Any insight into what might be causing the software to greatly underestimate an inlet's capacity? Is there a manual override for inlet efficiencies to "force" the software to use a specific efficiency at each inlet instead of the software determining the efficiency based on the analysis results?
  • When comparing the results from the software's analysis to calculations we performed following procedures in our design manual, we noted the software seems to consistently calculate higher flows from the catchments than the calculations we perform. We reviewed the catchment properties and hydrologic variables in the software and in our separate calculations and confirmed they are identical. Any insight into what may be causing this difference? 
  • It's our understanding the terrain surface only influences an inlets elevation when the inlet is placed relative to the terrain and snapped to a corridor element, like the curb flowline, and the terrain surface does not influence any of the software's calculations it performs. Is this correct?
  • Before laying out our storm sewer system we generated a very clean proposed terrain model. Even though we cannot find any "defects" or "gaps" in our terrain model the automated catchment delineation tools and placing gutters using the trace slope method do not work correctly, or only work intermittently. Any insight into what may be causing this issue?
  • In the utility properties for inlets we noted the cross slope and gutter cross slope should be entered as ft/ft. With a cross slope of 2.50% and a gutter cross slope of 8.33%, should those slopes be entered as 0.0250 and 0.0833 OR should those slopes be entered as 40 and 12? Or does it matter and either entry method is correct?
  • What is the post analysis node summary report meant to represent? It seems like it duplicates information or is some combination of information from the catchment summary and the inlet summary, except when you compare some of the results between the node summary and the other two summaries (i.e. catchment and inlet summaries), the values don't match. For example, we noticed the node summary was reporting different flows within the catchments than the catchment summary was reporting? Any insights into these differences?

Thanks so much for your help and any information is great!