In nature rain water runoff is typically filtered by vegetation or absorbed into the ground, however vehicles of all types constantly deposit oil, gasoline and other fluids onto the surface of paved parking lots and roadways where absorption is not possible. Rain water flushes all of these contaminants into the municipal storm sewer system that often drains untreated into water ways, lakes, rivers and streams destroying fish and wildlife habitat, and the fresh drinking water supply.


A storm water interceptor is installed along the same principle as a manhole but is designed to remove sediment, screen large debris and allow suspended oil and grease to separate from storm water runoff and be contained within the structure for future collection and environmentally sound removal.  Due to new environmental regulations all new commercial developments are required to treat the storm water runoff before it enters a municipal sewer system.


Installing a Storm Pal storm water interceptor will address these regulations. Semi–annual inspection and maintenance is mandatory for all storm water interceptors to operate effectively and this service is included in the total installation cost of a Storm Pal.


Installed SWI
Installed Water Interceptor

The Storm Pal Storm Water Interceptor (SWI) is a set of two or three treatment tanks installed in a storm sewer system similarly to manholes. The device is installed in an on-line configuration.  The Storm Pal SWI is designed to remove settleable solids and their associated pollutants, oil, and floatables from stormwater runoff.



The Storm Pal SWI has no moving parts and no external power requirements. A two tank configuration consists of two standard concrete manholes, installed below grade, with interconnections. The first in line manhole has an inlet pipe from the storm sewer. This first manhole has an upper and lower chamber separated by a trash gate. Both chambers have an outlet to the second in line manhole. The second manhole has an outlet to return flows to the storm sewer. Ports at grade provide access for inspection and clean-out of stored floatables and sediment.


Installed SWI

At lower flowrates, stormwater flows into the first manhole, through the trash gate into the lower chamber. Stormwater exits the lower chamber to the second manhole through an inverted elbow. In case the trash grate becomes plug, stormwater may bypass the lower chamber in the first manhole and exit through an inverted elbow in the upper chamber that also connects to the second manhole.


Otherwise all the storm- water is passed through the lower conduit having the same diameter as the outflow conduit in the secondary treatment tank. From analyzing sediment depth on maintenance reports, resuspension of settled solids is not an issue.