Rainwater harvesting: TTT

From LID SWM Planning and Design Guide
Revision as of 13:03, 18 September 2017 by Jenny Hill (talk | contribs)
Jump to navigation Jump to search

TTT.png

Once the size of cistern has been determined, it can easily be modeled in many open source and proprietary applications. For planning purposes, a RWH system could be integrated into a site plan using STEP's Treatment Train Tool. This tool provides a graphical user interface and simplified inputs on the EPA SWMM model. It is free to download, click image above. In a typical configuration:

Surface
Catchment (roof) 100% impervious
The rainwater harvesting system would be a 'Storage' Element with the following properties:
Storage type No removal
? Lined
Underlying soil Doesn't matter
Evaporation factor 0
Suction head (mm) 0
Saturated conductivity (mm/hr) 0
Initial soil moisture deficit (fraction) 0
The dimensions of the rainwater cistern can be placed into the fields:
  1. Bottom elevation (m)
  2. Maximum depth (m)
  3. Initial water depth (m)

The Curves table is designed to accommodate ponds of roughly conical dimensions. A rainwater cistern is usually cuboid or cylindrical in shape, so that the area (m2) will remain the same throughout the depth.