Hydro-Cartridge Operating Manual
Revised 01/01/2008

Prepared By:
Advanced Aquatic Products Int’l, Inc.

AAPI Copyright 1993-2008
All rights Reserved.


Description and Features
Mechanism of Operation
Installation Procedures
Maintenance Procedures
Handling of Collected Wastes: Sediment
Handling of Wastes: Petroleum Filters

Description & Features

The Hydro-Cartridgeis a patented fiberplastic pollution-control system designed to retrofit existing stormwater drains of various dimensions and shapes. Its purpose is to intercept the various solid and liquid components commonly found in stormwater runoff flows. It will prevent these pollutants from entering the stormwater discharge and elimination systems which flow into retention ponds, waterways, lakes and oceans. The Hydro-Cartridge possesses several very beneficial features. It will:

1) Trap solids such as silt, rocks and other heavier than water substances that routinely enter stormdrains during rainfall events or other activities, such as construction or street sweeping. Many of these sediments have been proven to contain pollutants such as heavy metals;

2) Trap a variety of petroleum hydrocarbon liquids that also flow routinely into stormdrains during rainfall events or during emergency spills onto roadways. A specially designed Hydro-Cartridge Petroleum FilterTM absorbs liquid petroleum and locks it up permanently in a cross-linked polymer matrix. This effectively transforms these hazardous hydrocarbons into a benign, rubberized solid that is easy and safe to both handle and dispose. This material exceeds all current EPA and California (USA) environmental standards for absorbents;

3) Hold spills of a solid or liquid nature in the event of an emergency such as a drum rupture or fuel tank leak. Depending on the particular model of Hydro-Cartridgeused, a volume from 10 gallons to over 50 gallons will be held thus preventing an unwanted flow of solid or liquid material into the stormdrain structure;

4) Provide simple and cost-effective retrofitting for the many stormdrains in use by cities and industries required to address NPDES, CZARA & CWA regulations;

5) Allow monitoring of stormwater pollutants and can aid illegal discharge detection of both solid and liquid materials; and

6) Allow for fast and easy maintenance by existing general maintenance personnel or from third party contractors licensed to handle hazardous wastes.


The Hydro-Cartridge is designed to be compatible with the variety of standard drainage structures used in the past, currently in use and contemplated in the future. The majority of basic designs are either rectangular, square or circular with numerous aspect ratios in the United States and elsewhere. This makes the possible combination of different designs quite staggering, but the Hydro-Cartridge is able to fit the majority of systems in use through clever design features and adapting plates. To assist with the selection of the correct Hydro-Cartridge model, the model number matches the standard manufacturing code numbers that are generally stamped into the grate during manufacture. Most areas of the country have a majority of stormdrain grates from one or two local suppliers of cast iron products. Therefor, in each state or region where a primary manufacturer or supplier is identified, the use of their particular grate code will also be the same as the Hydro-Cartridge model specified for that grate. Exceptions will be noted by us. For example, a standard rectangular drain size in South Florida is 14” x 25”. Most of the stormdrains in this region are manufactured by the local company, U.S. Precast. Their number for the grate to fit this stormdrain is known by the code number “4102.” Therefore, a city engineer would specify a “Hydro-Cartridge Model 4102” for a unit that properly fits this particular size of stormdrain frame and grate. In all cases, the suffix of S, M or L designates the unit’s depth (e.g. 4102 L or 4105 S). A Small unit is for vaults 18” deep; Medium is up to 30” deep; Large is up to 42” deep. The depth of the Hydro-Cartridge affects the capacity of the system when retaining liquid spills and is generally sized by the available depth of the stormdrain structure. In general, the deeper the Hydro-Cartridgeused the better its ability to separate lighter density liquids, i.e. liquid petroleum runoff will tend to stay on the surface of the inlet area since it must travel through a longer column of water to be discharged into the stormdrain structure. Also, the greater the depth the greater the emergency holding capacity of the system during emergency spill events. Finally, the greater the depth of the system used the greater the solid holding capacity also. This can affect the periodicity of the maintenance required to keep the system operating at top efficiency; i.e. with a greater holding capacity the deeper systems will not need to be cleaned as often.

Mechanism of Operation

The Hydro-Cartridgeis designed with simple but effective operating characteristics that allow it to perform several functions with regard to NPDES TMDL reductions. The natural principles of liquid dynamics captures the many runoff solids and liquids found in runoff flows and are effectively trapped and held for later removal. When stormwater flows enter the input of the Hydro-Cartridge system water is usually already present due to the design which acts like a trap. This causes flows of solids to slow down immediately and suspends the solids within the flow. Liquids of different density, like most petroleum hydrocarbons, will begin to float to the surface. In the case of faster flows of stormwater, most of the low density liquids will suspend in the upper portion of the system allowing the higher density water to pass by and eventually discharge into the stormdrain structure. During very high volume flows some emulsification of light density liquids will occur. Solids will begin to eventually precipitate out of the flow and settle at the bottom of the Hydro-Cartridge. The flow of the water then changes direction and flows up both sides of the system, away from the center core where the flows came from originally. This side flow eventually discharges toward the top and sides of the unit and into the stormdrain structure. At the entrance to the system, the Hydro-Cartridge Petroleum FilterTM attracts the lighter density petroleum hydrocarbons that flow from the roadway surface. The material in the filter is designed to capture and hold permanently any petroleum hydrocarbons that may be in the stormwater flow. During high volume flows of stormwater, the filter is less effective than when the flow of stormwater goes to zero. When no flow is going into the system the ability of the liquids of differing density to separate is increased. This causes the petroleum hydrocarbon portion of the flow to separate out and float on the surface in direct contact with the Hydrocartridge Petroleum FilterTM. The capture time for the filter is from a few seconds for lighter hydrocarbons, such as gasoline, up to 5 minutes for heavier oils. In case of a large release of liquid contaminates that find their way into stormdrains fitted with the Hydro-Cartridge system another design feature becomes apparent. The system is able to hold a relatively large capacity; over 40 gallons in some cases of solids and/or liquids that occur during a spill onto the roadway. This will prevent undesirable flows of contaminates into the stormdrain structure and associated distribution and discharge pipes. This facilitates cleanup of the spilled contaminates and prevents a costly cleaning process of the underground structure and pipes. The Hydro-Cartridgeis a very effective first line of defense when dealing with potential leaks and associated flows to stormdrains for many situations. Because of its fiberplastic construction the system is able to withstand exposure to a wide range of liquid contaminates including acids and strong solvents such as TCE or Benzene. Additionally, the Hydro-Cartridgewill hold high density contaminates, such as concrete, safely and will not cause buckling or collapse of the system while preventing their flow into the stormdrain structure.

Installation Procedure

Installation of the Hydro-Cartridgeis simple and straightforward. Generally, one person is able to handle all aspects of installation and a minimum of equipment is required. The general procedure is outlined as follows:

1) Remove the grate to the stormdrain structure.

2) Use a wire brush to clean rocks and dirt from the grate frame.

3) Insert the Hydro-Cartridgeinto the structure so it hangs on the frame.

4) Install a Hydrocartridge Filter with plastic zip ties to the lifting hooks.

5) Reset the grate onto the grate frame.

6) (Optional) Fill the Hydro-Cartridge with water. The entire procedure will take less than 10 minutes to complete in most cases. In the case of large stormdrain structures, such as those commonly found at airports, it may require two persons to remove the grate. Step 6 is optional but helps the system to work immediately to capture petroleum hydrocarbons. Without water in the system initially, the system will first fill up with water thereby allowing only minimal contact of the water/petroleum layer with the filter. Preloading with water makes it immediately more efficient in case of a spill.

Maintenance Procedure

The Hydro-Cartridge is very easily monitored and maintained by normal maintenance personnel. Depending on the location of the system the frequency of maintenance visits is a factor of the surrounding area. For example, a system installed next to a vehicle maintenance area will generally require cleaning and filter replacement more often than a system installed at a suburban setting. Therefore, a maintenance record should be kept not only to prove the system has been properly maintained but to also help determine the frequency of visits to keep the system operating at top efficiency. An example of such a record is provided in the attachment section. The maintenance of the Hydro-Cartridge system is uncomplicated and easily performed by one maintenance person. During regular visits to the site, a measurement of the solids level can be performed using a calibrated rod that is inserted through the storm grate to the bottom of the system. When the solids have reached a point that they begin to block the flow of water the system is ready for a cleaning operation. The procedure is as follows:

1) Remove the stormdrain grate.

2) Observe the Hydro-Cartridge Filter at the top of the system. If saturated with oil remove and place into a DOT approved drum or container.

3) Using the pipe adapter attached to the suction hose of a pump out truck, insert the extractor pipe to the bottom of the Hydro-Cartridgeand begin sucking out the solids and water into the pump out truck until removed.

4) (Optional) Fill the system with water.

5) Attach a new Hydro-Cartridge Filter to the lifting hooks using plastic zip ties. Only the specially designed, tested and approved filters from Advanced Aquatic Products should be utilized for maximum efficiency and safety. Use of any other will void any manufacturer warranties.

6) Reinstall the stormdrain grate.

As previously noted, a maintenance record should be filled out to help track activity at each site and to prove the proper maintenance has been performed to the satisfaction of local regulatory agency personnel. Records can also act as evidence in cases where illegal discharges or dumping has been observed. Accurate records can also aid detection of pollution problems that were unanticipated. In cases where monitoring is required, samples of the solids and the filter should be kept and properly labeled for future analysis by a laboratory. This could aid DEP enforcement officials in locating the source of illegal pollutant discharges and the prevention of illegal dumping into the stormdrain system.

Handling of Wastes—Sediments

Currently, there are no laws governing the specifics of stormdrain waste handling. Studies have shown that a number of pollutants, especially heavy metals, are contained in the solids found in stormdrains. As NPDES evolves it is anticipated that greater scrutiny will occur with regard to the handling and disposition of stormwater runoff wastes. As such, we believe that all wastes coming from the use of the Hydro-Cartridge should be handled in a safe manner since we do have some idea of the contaminates commonly found. We have been recommending that the label “Uncharacterized Wastes” be used on drums or containers that store the solids coming from Hydro-Cartridge maintenance. Until a sample is removed and properly tested by a laboratory it is only conjecture as to what exactly is in the solids removed from the system. The issue of stormwater runoff will become more clear in the future as to the responsibility of proper handling of contaminates. Many issues have yet to be faced, such as the legal aspects of who is ultimately responsible for these contaminants, especially when collected from public areas which the local government is normally responsible to maintain. As we know, a variety of contaminates currently flow into drain systems without monitoring of any type. This is why the NPDES laws were developed. In general, these solids collected from the system should be handled as a toxic waste solid. It is therefore necessary to store this material in DOT approved drums for proper landfill disposal. Until some other method of disposal or use of the contaminated solids is developed this is the basic procedure necessary to insure that the solids will not contaminate some other site. Just spreading the sediment onto the surface of some piece of land just won’t do. It is the basic responsibility of the maintenance contractor to document that proper handling of the solids has been achieved on behalf of the party who is using the Hydro-Cartridge system to meet NPDES guidelines on their property.


Handling of Wastes—Petroleum Hydrocarbon Filters

With regard to the petroleum hydrocarbons collected by the filter we have a straightforward means of dealing with the problem. The filters are composed of a cross-linked copolymer. It has tremendous affinity for liquid hydrocarbons (petroleum). This material has been extensively tested by EPA and has over 18 years of use history without incident. The State of California has even allowed landfilling of filters containing PCB oils since the filter is designed to lock in contaminates permanently. When properly incinerated, the Polymer material by itself only releases water and carbon dioxide (complete combustion). There is a built in heat value of approximately 18,000 Btu’s per pound, making it an excellent secondary fuel material. For this reason, it is generally safe to incinerate the HydroCartridgePetroleum FiltersTM after they have been used to collect waste petroleum. Once the filter has been removed from the Hydro-Cartridgeduring regular maintenance it should be placed into a proper storage container such as a DOT approved drum and sealed. The filter will hold the liquid hydrocarbon by transforming the liquid into an easy to deal with solid that will not leach out, even when run over with a truck! For this reason the handling & transportation of the filters is a relatively safe procedure; even if a barrel were to split open after falling off a vehicle, there is little or no chance of any contaminated liquid release. This makes dealing with the disposal of the filters much safer than leachable types.  No other materials should be used in place of these special filters and any substitutions will void the manufacturer’s warranty. These filters have been evaluated in EPA sponsored NPDES testing and are very effective in removing surface contamination of the water to below 5 ppm. Once the filters have been collected, they may be stored indefinitely and will not evaporate or leach any of the collected petroleum hydrocarbons. In this form we have two options: landfill the waste filters or incinerate them. We recommend the second option, since there is the opportunity to actually sell the filters as a waste-fuel source. The Btu value of differing petroleum hydrocarbon we have collected is still available in solid form, in addition to the Btu value of the filter itself. By incinerating the filters there is zero chance of future contamination occurring……ever. And, the filters can be converted into something useful, like electricity, for the good of the community. It becomes a real ‘win-win’ situation for all concerned.

Hydro-Cartridge users should consult with an environmental waste handling professional as well as their Local and State environmental regulatory agency when determining the handling procedures and the proper and legal disposal of stormwater discharge-related wastes.  

Home | Design Features | Operating Manual