Dual Drainage System Design

Design, model and analyze dual drainage systems for flood control in new, existing or combined developments. Surface flows routed overland (major systems such as roads, swales, street sags, storage areas) can easily and accurately be combined with underground flows (minor system, such as sewer infrastructure).

PCSWMM provides innovative tools for fast, accurate major/minor system modeling, analysis and design. This means that the program can be used for the design and analysis of (i) new, (ii) existing and (iii) combined new and old, urban drainage systems where surface flows are routed over the land surface (major system, such as roads, swales, street sags and storage areas) while part of the runoff simultaneously flows in the underground conveyances (minor system, such as sewer pipes and associated infrastructure). Our users tell us that the PCSWMM dual drainage tools are incredibly easy-to-use, almost too much so. The tools automatically dovetail with any or all SWMM5 engines, and with an extraordinarily wide array of established, included design storms (from 1:100 and larger to 1:1 and smaller) and long-term continuous rain data. Especially useful is the ability to simultaneously plot on one or more screens the longitudinal profile and dynamic energy and hydraulic grade profiles for all parts of the dual drainage system.

Unlimited network sizes and unlimited time steps are allowed, and the dual drainage systems need not be parallel (they may flow in arbitrary directions). Unlimited numbers and sizes of control devices and storages are allowed on both systems. Sensitivity, optimization/calibration and error analysis tools are provided for optimal design. Time-steps are semi-infinitely variable, and the usual infiltration and runoff-generating options, such as triangular unit hydrographs, are optionally available. The program will also automatically determine the minimum conveyance sizes required, including estimation of required minimum storage.

If your application includes simultaneous surface ponding, street flooding and surcharged pipes, you should step up to dynamic analysis of dual systems, with dynamic wave routing allowing for flexible inlet control, catchbasin flooding and reverse flow, street/gutter flow and overland routing, accurate surcharge and pressure flow pipe modeling, inlet/outlet controls, flooded and ponded areas, trap-lows, and much more.

  • Automate the creation of your major system with the Dual Drainage Creator
  • Easily develop detailed street cross-sections with the Street Designer
  • Efficiently assign inlet control (based on rating curves or capacity) for individual catchbasins or aggregated inlets
  • Automatically adjust junction inverts to meet minimum slope criteria
  • Accurately model manhole drops and account for varying energy losses at junctions
  • Assess the impact of multiple Low Impact Development (LID) practices
  • Create design storms for both major and minor events with the comprehensive storm distribution library in the Design Storm Creator tool, including standard SCS, Huff, AES, Chicago, etc. as well as locally-required design storm distributions
  • Automatically size pipes based on computed peak flows
  • Quickly tweak and test design parameters (diameters, inverts, etc.) directly in the profile view for computed HGL
  • Easily check for design criteria such as depth of cover, minimum slope, etc.
  • Perform long term, continuous modeling verification of dual drainage performance
  • Compare design alternatives with comprehensive scenario analysis graphs, profiles and reports