"The GISB is an Economical and Versatile Filter Solution for use in Grated Catch Basins with Low Cost Maintenance & Proven Performance.”
Grate Inlet Skimmer Box™ (GISB™)
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The Grate Inlet Skimmer Box™ (GISB™) is a specialized inlet filter specifically for use in grated catch basins. The unit is made of marine grade fiberglass and stainless steel to ensure longevity and durability. During a storm event, all incoming runoff passes through the internal skimmer tray and into contact with a Stormboom™. Stormwater and solid material then fall into the lower section of the skimmer box where small sieve sized filters capture and retain all solids. Turbulence deflectors within the filtration box act to calm the water and allow for a greater removal efficiency. Purified stormwater passes through the catch basin allowing the filtered materials to dry after each storm.
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Benefits
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GISB Highlights:
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LEED Credit Applicable:
6.2 Stormwater Design, Quality Control
6.2 Stormwater Design, Quality Control
Operation
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To better understand the functionality of the GISB™, please view the accompanying video to see the entire system in action.
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Stage 1: Hydrocarbon Absorption
Stormwater enters the inlet immediately coming in contact with a StormBoom™ which absorbs floating hydrocarbons. The StormBoom™ can be outfitted with multiple types of biosorption activated media and is installed around the top perimeter. |
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Stage 2: Fine Particulate Filtering
Throughout the storm event, water continues to come in contact with the StormBoom™ and then flows into the lower filtration chamber adjacent to the fine sieve size screens. The fine sieve size screens filter out extra fine particulates such as phosphates and sand. |
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Stage 3: Medium Particulate Filtering
As the storm intensity increases, the water level in the GISB™ rises to a level adjacent with the medium size sieve screens and turbulence deflector. The medium size sieve screens provide additional flow with less chance of clogs or obstructions forming. The turbulence deflector reduces the turbidity in the lower chamber and prevents scouring. |
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Stage 4: Coarse Particulate Filtering
If the storm intensity becomes a high flow event, the water level in the GISB™ rises to a level adjacent to the coarse sieve size screens above the turbulence deflector. The coarse screen provides additional filtered flow with a far less chance of obstruction than the fine or medium sieve size screens and is designed to capture floating debris like foliage and trash. |
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Stage 5: Filter Bypass
If the stormwater flow rate is extreme or the unit is full where the flow rate exceeds flow through all the screens, the water will bypass the screens by passing through skimmer protected openings at the top of the GISB™. |
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Stage 6: Dry State Storage
After the storm event has subsided, the stormwater will drain from the GISB™ completely leaving all collected debris suspended in the screen system to dry until removed during routine service. The dry state storage contains the nutrient pollutant load while also working to prevent septic water, the breeding of mosquitoes and nutrient leaching. |
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Service & Maintenance
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Service Information
The GISB™ is recommended to be inspected and serviced quarterly. However, site conditions can affect the service interval to be a longer or shorter time period. The maximum flow capacity of the unit will be restored after each servicing no matter the times serviced due to durable stainless steel construction. Service can be carried out either manually or via vacuum truck. Manual Service Procedure
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Vacuum Service Procedure
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StormBoom™ (Optional)
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StormBoom™ Absorption Media
A StormBoom™ is a hydrocarbon absorption media sock used within stormwater BMP's to remove chemicals and hydrocarbons from stormwater runoff. Developed into four distinct types, StormBoom's™ can cover a wide spectrum of pollutants suited for an array of stormwater applications. Benefits
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Type 1: Hydrophobic Treated Cellulose
A wide spectrum absorbent with a large sieve size covering for greater stormwater penetration. Hydrophobic treated cellulose filler is made from reclaimed paper mill by-products and certified 100% recycled material. Absorbed liquids are drawn into the cellulose fibers via capillary action and are encapsulated. |
Type 2: Melt Blown Polypropylene
A non biodegradable large sieve size covering filled with shredded melt blown polypropylene. This media has indefinite lifespan with absorption limited to hydrocarbons and oils. |
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Type 3: 50 - 50 Types 1 & 2 Blend
50 - 50 blend of Hydrophobic Treated Cellulose and Melt Blown Polypropylene with a large sieve size covering. This media blend offers wide spectrum absorption with a particular emphasis on hydrocarbons. |
Type 4: Polymer Crumb Filler
A non biodegradable fine sieve size covering filled with polymer crumb filler. This media will not absorb water and is limited to hydrocarbon absorption via a chemical bond with hydrocarbon molecules on contact. This media is recommended for use near the outflow. |
