Rain Guardian Bunker

The Bunker is constructed of recycled plastic (95%+) and is well suited for residential applications.

General Information:

The Rain Guardian Bunker is constructed of high density polyethylene (HDPE) recycled plastic lumber (95%+). HDPE provides the strength and functionality of wood with plastic’s ultra-resistance to rot, pests, and weather.

The Bunker top grate can handle a 316 lb. concentrated load to facilitate most individual foot traffic and weighs just 35 pounds for easy maintenance.

The Bunker is ideally suited for residential rain garden settings. The lightweight steel grate and simple rectangular design make cleanout and maintenance quick and easy

Design Considerations:

Drainage Area: Designed overflow points ensure water is not restricted from entering the bioretention practice. Routing large drainage areas to a single pretreatment chamber will simply result in the need for more frequent maintenance.

The Bunker inlet facilitates hydraulic passage of up to 3.07 CFS (ft3/s). The Bunker outlet facilitates hydraulic passage of up to 6.11 CFS (ft3/s). The internal storage capacity of the Bunker is 2.85 CF (ft3).  

Garden Depth: The standard Bunker is designed for a standard ponding depth of 12”. However, with simple modifications, Bunkers can easily be installed in bioretention practices with ponding depths shallower or deeper than 12”. In deeper bioretention practices, a gradual slope can be used to transition from the base of the Rain Guardian to the base of the practice. In the case of a shallower practice, a simple course of retaining wall block creates a small area next to the chamber to allow installation at the proper elevation. There is also an alternative version of the Bunker that facilitates a 9” ponding depth.