Rain Guardian Foxhole

Linear pretreatment and conveyance for routing runoff under paths or boulevards.

The Rain Guardian Foxhole is a concrete modular pretreatment chamber designed to route runoff beneath walkways, trails, and boulevards while preserving usable bioretention area. Its linear configuration and traffic-rated components allow designers to maintain surface continuity without sacrificing pretreatment performance.

Product Overview

The Foxhole features high-strength fiberglass lids rated for vehicle traffic up to 14,160 pounds, equivalent to 3,540 pounds per square foot. Each lid weighs approximately 52 pounds, allowing efficient access for inspection and maintenance.

The modular system is configurable in three-foot increments, making it adaptable to a range of inlet lengths and site geometries. This flexibility allows runoff to be conveyed below hardscape features while maintaining treatment functionality.

Performance and Design Considerations

Hydraulic Performance
The Foxhole is designed to provide effective pretreatment while conveying runoff to downstream bioretention practices.

• Inlet capacity: up to 2.00 cubic feet per second

• Outlet capacity: up to 4.39 cubic feet per second

Internal storage capacity varies by module configuration:

• Inlet or outlet section: 1.73 cubic feet per unit

• Middle section: 2.20 cubic feet per unit

Storage volume can be scaled by adding middle sections to meet site-specific needs.

Ponding Depth Flexibility
The Rain Guardian Foxhole is designed for a standard 9-inch ponding depth. With minor field modifications, the unit can be installed in bioretention practices with both shallower and deeper ponding depths.

For shallower practices, a course of retaining wall block can be used adjacent to the chamber to achieve the proper installation elevation. For deeper practices, a gradual slope that is properly stabilized can be used to transition from the base of the Foxhole to the base of the bioretention practice.