Engineering Design Guide

This guide is provided to assist you design the StormChamber™.

1. Calculation of StormChamber™ 115 Cubic Feet Design Storage.

The void space in the open StormChamber™

2. Using additional stone to increase the Design Storage Capacity.

The design requirement for a 6" stone base and 6" of stone above the StormChambers™ is a minimum requirement. The depth of the stone base and/or the stone on top of the StormChambers™ can be increased in order to provide additional Design Storage Capacity. This may be desirable for projects where the site is tight. Each additional 108 cubic feet of stone, (4 cubic yards), will provide an additional 43.2 cubic feet of storage.

3. Replacing soil fill above the StormChambers™ with additional stone.

The minimum 6" of stone above the StormChambers™ can be extended up to the subgrade for the base of the pavement. This may be desirable where the excavated soil is required elsewhere or the excavated soil can not meet compaction and other backfill specifications, or where it will facilitate pavement installation.

4. Lateral (side) pipe connections.

The purpose of the lateral (side) pipe connections between the rows of StormChambers™ is to help ensure proper flow dynamics between StormChamber™ rows during high flow periods. These connections do not need to be water tight. Although the StormChambers™ all interconnect hydraulically through the surrounding stone, the pipe connections provide a flow path that can carry higher short duration flows.

Smooth walled (inside and outside) pipe of 8", 10", or 12" diameter should be specified. Most often 8" PVC pipe is used. Corrugated pipe is very difficult to use in this application. Lateral pipe connections must be aligned directly across from each other, at the point where drain pipe feeds the StormChamber™ . The lateral pipe connections will be across the first chambers of each row (the Start StormChambers™ ). Additional connections across all StormChamber™ rows must be specified so that the total amount of flow capacity between any given pair of StormChamber™ rows is at least the same as the total flow capacity of the storm drain inlet pipes. The additional inter row connections can be made anywhere along the rows, up to 2/3 down the length of the rows. It is recommended that all interconnections be directly across from each other.

5. Detail sheet.

The CD that comes with your StormChamber™ design manual contains an AutoCad file with details that can be copied directly to you plans. Please include all this information on your detail sheet, along with anything else you feel will be of help to the contractor. The information we have provided reflects questions and concerns raised by contractors on previous installations.

6. Clean out / inspection risers.

The top portal on the "down stream" end of the StormChamber™ includes indented circles as cut out guides for an 8" or 10" smooth-walled (inside and outside) riser pipe. An 8" riser should be specified if it is to function solely as an observation well. The 10" riser must be specified if it is to also function as access for clean out by a vacuum truck. When specified for clean out, a 10" riser pipe should be placed at the last chamber in each row that receives a drain pipe feed. This is where the majority of sediment is predicted to concentrate. If additional clean out opportunity is desired, or if infrequent maintenance is anticipated, an additional 10" riser can be placed at the end of the adjacent row. This is the next most likely place that sediment is predicted to concentrate.

When the StormChambers™ are used for individual homes to capture roof runoff, an 8" riser is sufficient. In these applications, all that is needed is an observation well; very little sediment would accumulate from roof runoff.

7. Sediment treatment and removal.

Sediment pollutants can be treated and removed in several ways. 1. A pre-treatment separator device can be installed "up stream" of the chamber system. 2. A four foot sump with hood can be incorporated into the inlet structures. 3. Sediment can be removed through the clean out risers on the StormChambers™ , or 4. Any combination of these approaches can be utilized.

8. Debris treatment and removal.

Two different approaches to debris maintenance are recommended. Grated inlet structures and debris trash racks for throated inlets can be used to prevent the larger debris from entering the system, or a pre-treatment device can be incorporated "up stream" of the StormChamber™ system. Use of a pre-treatment device will also address the sediment maintenance concern.