This guide is provided to assist you design the StormChamber.
1. Calculation of StormChamber 115 Cubic Feet Design Storage – for 34” installed storage capacity.
The void space in the StormChamber is 75 cubic feet. With the typical installation which includes 6” of stone above and below, and 9” between at the foot, the installed storage capacity increases to 115 cubic feet per chamber.
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. Stacking up to 4 layers to increase the design storage capacity.
Due to the strength and material properties, StormChambers have been stacked up to four layers. The layers are separated with 12” of the stone. We can provide you with independent testing results and references.
4. 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 cannot meet compaction and other backfill specifications, or where it will facilitate pavement installation.
5. Lateral (side) pipe connections instead of header pipe manifold system.
The purpose of the lateral (side) pipe connections between the first chamber of the inflow and adjacent rows of StormChambers is to help ensure proper flow dynamics between StormChambers 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 comparable to an emergency spillway for a dam. Smooth walled (inside and outside) pipe of 8, 10, or 12 inch diameter should be specified. Most often 8 inch PVC pipe is used. Corrugated pipe is very difficult to use in this application. Lateral pipe connections must be aligned directly6 across from each other, at the point where drain pipe feeds the StormChamber.
6. Detail sheet.
The detail sheet found under “Downloads” contains an AutoCad file with details that can be copied directly to your 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 the contractor on previous installations.
7. Sediment treatment and removal.
Sediment is easily managed with our patented SedimenTrap (see SedimenTrap under “Products.)” Also view the animated video “See how StormChambers provide water quality.” Under “Downloads” read “The StormChamber System as a water quality device.” We also recommend four foot sump in the upstream to help capture the heavier sediments. In combination with the BMP “Snout” (see below), expensive pre-treatment units can be eliminated.
8. Debris and oil treatment removal.
Grated inlet structures and debris trash racks for throated inlets can be used to prevent the larger debris from entering the system. It is highly recommended that a Snout, manufactured by BMP, Inc. be incorporated into the manhole(s) upstream from the StormChamber system. The snouts will prevent the smaller floatable and oil and grease from entering the StormChamber system. Click on “Downloads” for more information on the “Snout.”
9. Inflow alternatives.
Typically inflow is directed to the first chamber in the first row with the outflow out the last chamber in the last row. This provides for maximum retention time on the bio mat that forms on the underlying stone and soil, similar to the function of a septic drain field. Inflow can also be directed into the side portal of any chamber(s) of either outside row. The use of larger diameter pipes along the outside rows is accommodated for an inexpensive highly effective approach by eliminating one of the outer row chambers. Click on “Downloads” for StormChamber Detail Sheet. Surface drains can be directly connected vertically into a 12 inch riser pipe through the top portal, directly above a Sedimentrap.