The maximum depth of the manhole junction is the distance from its invert to the ground surface elevation where street flooding would begin to occur. The invert elevation establishes the junction’s vertical placement in the H2OMAP SWMM model. The invert elevation of the manhole junction is the elevation of the bottom of the manhole relative to the model’s datum (such as mean sea level).
Post-development site with simple drainage systemįigure 7‑2. The parameters needed to characterize this type of node-link arrangement are as follows:įigure 7‑1. The details of the gutter inlet and drop structures that make the actual connection with the manholes are not important for our purpose.
#Pcswmm 7.1 plus
It consists of a below-grade circular pipe connected to manhole junctions on either end, plus an above grade street and gutter channel also connected to the same two manhole junctions. An example of the parallel pipe and gutter conveyance arrangement that will be used in this example is shown in Figure 7‑2. The pipe system will be sized for the 2-yr event and its behavior observed during the major storm (100-yr event).Įxample 2 introduced junction nodes and conduit links as the basic elements of a drainage network. Thus, in this example the pipes and flow in gutters represent the minor system, and the channel in the park and the flow in streets represent the major system. The cross sections of these gutters will be that of a typical street, representing the surface “channel” through which water would flow if the pipe system surcharged and flooded the street. Gutters will also be added to the upstream section of the study area.
#Pcswmm 7.1 series
A series of below ground pipes will be added to the site that share inlets with the open (surface) channel running through the park. Example 2 modeled the drainage system with open channels and culverts whose invert elevations were the same as the ground surface elevations found on the site contour map. In particular, the entire street (not only the gutters) becomes a conveyance element.įigure 7‑1 shows the post-development layout of the site analyzed in Example 2 (refer to ‘ EX2-POST’ ‘parent’, ‘child’ and ‘grandchild’ scenarios in ‘ H2OMAP SWMM Applications.HSM’).
For large events these pipes surcharge and flood, and the major system handles the flows (Grigg, 1996). For frequent events the minor or “initial” system operates (Grigg, 1996) overland flows are conveyed by gutters and enter into the pipe system. The objective of this example is to simulate the interaction between the minor and major drainage systems through the interconnection of part of their underground and surface sections. See the accompanying ‘ H2OMAP SWMM Applications.HSM’ model, scenario ‘ EX7-DUAL_DRAINAGE’ (with ‘child’ and ‘grandchild’ scenarios) for a complete worked out solution. Particular attention will be paid to the interaction between the below-ground storm sewer flows and the above-ground street flows that occurs during high rainfall events. Both the 2-yr and 100-yr design storms will be used to size and analyze the performance of this expanded dual drainage system.
A series of storm sewer pipes placed below the existing swales will also be added to help drain the downstream section of the site’s park area. Example 7 will convert some of the open channels in Example 2 to parallel pipe and gutter systems. The three hydraulic routing methods (Steady Flow, Kinematic Wave and Dynamic Wave) were introduced and their effects on the drainage system behavior shown. The post-development model in Example 2 simulated simple hydraulic routing within a surface drainage system that employed open channels in the form of gutters and swales. Dual Drainage Systems in InfoSWMM and InfoSWMM SA
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