A practical, question-led look at how Ultra Urban® Filter catch basin inserts and Smart Sponge® media address heavy metals, bacteria, TSS and other stormwater pollutants under NPDES and MS4 permits.
A catch basin insert filter for stormwater is a media-filled unit that drops into an existing storm drain or deck drain to treat runoff before it leaves the site. Abtech Industries builds the Ultra Urban® Filter, a custom-fabricated insert loaded with Smart Sponge® media, so municipal and industrial permit holders can target specific pollutants without rebuilding drainage infrastructure. Because the insert fits the basin rather than the other way around, it works as a retrofit on catch basins already in service.
What Problem Does a Catch Basin Insert Solve Under NPDES and MS4 Permits?
Every storm event is a compliance event for permit holders operating under NPDES, MS4, MSGP or SWPPP programs. Runoff crosses parking lots, rooftops, yards and process areas, picking up sediment, oil, metals, nutrients and bacteria before it reaches the outfall. A catch basin sits at the point where that runoff enters the storm drain system, which makes it a practical place to intervene before pollutants travel further downstream. The stormwater treatment page describes this as putting treatment in the path of runoff rather than waiting for it to reach a detention pond or receiving water.
For municipalities and public works departments, that matters because MS4 permits set pollutant-reduction expectations across the whole storm sewer system, not just one outfall. Retrofitting existing catch basins with inserts avoids the cost and disruption of installing new structural controls, which is part of why Abtech treats format selection as a site-specific decision rather than a one-size answer.
How Does Smart Sponge® HM Address Heavy Metals and Phosphorus at the Catch Basin?
Facilities such as metal recycling yards, metal fabrication shops and scrap or junkyard operations generate runoff that can carry dissolved metals, including lead, arsenic, selenium, zinc and copper. Smart Sponge® HM is the media formulated for this contaminant group, and it also targets phosphorus, which makes it relevant for municipal wastewater facilities managing nutrient limits. Because Smart Sponge® HM is a media, not a format, it can be loaded into the same Ultra Urban® Filter insert used for other contaminants, or into vaults, pressure vessels and skids depending on where the flow needs to be treated.
Abtech's site-first process applies here: the team reviews contaminant concentrations, flow patterns, available space and effluent targets before recommending a media and format combination. For dissolved-metal projects, laboratory column testing on the customer's own water sample can help confirm which media configuration fits the chemistry actually present at the site.
Can a Catch Basin Insert Reduce Bacteria in Stormwater Runoff?
Bacteria are one of the harder pollutants to manage because they cannot be screened out the way sediment or trash can. Smart Sponge® Plus is an antimicrobial media built specifically to target bacteria such as E. coli and coliform in stormwater. This matters for coastal and municipal permit holders dealing with beach-closure risk or bacteria-driven TMDLs, where the runoff entering a catch basin upstream of a swimming area or harbor carries measurable bacterial loading. The guide on reducing bacteria in stormwater runoff covers where this contamination originates and why it is difficult to treat with conventional filtration alone.
What Makes an Insert a Full Trash Capture System, and Why Does TSS Removal Matter?
Beyond dissolved contaminants, catch basin inserts also serve a mechanical role: capturing trash, debris and total suspended solids (TSS) before they enter the storm drain. The Ultra Urban® Filter is fabricated to fit the specific basin it serves, and its filtration structure is designed to capture particulates while maintaining flow, which supports the trash and debris capture function that many stormwater programs require as a baseline best management practice (BMP). Sediment and TSS control is also the entry point for combining media in a single system — an insert can carry a Smart Sponge® formulation for TSS alongside Smart Sponge® HM or Smart Sponge® Plus depending on what the site's water quality data shows.
How Does Media Selection Work for Airports, DOTs, and Industrial Sites?
Large paved catchments operated by airports, departments of transportation and industrial facilities each have different contaminant mixes and flow conditions. Published applications include Ultra-Urban® Filters selected to treat deicing-season runoff across airfield catchments and catch basin inserts used in municipal storm drains to meet MS4 targets. In both cases, the format is the same insert technology, but the media loaded inside it is matched to what the site's runoff actually carries — deicing chemicals and TOC-contributing compounds call for a different media profile than a metal yard's dissolved-metal load.
This is also where industrial stormwater permit holders managing oil and grease action levels benefit from the standard Smart Sponge® media, which is hydrophobic and oil-attracting, binding hydrocarbons into a stable solid rather than releasing them back into the water column as flow continues.
Frequently Asked Questions
Do catch basin inserts require pumps or power?
No. Smart Sponge® media and the Ultra Urban® Filter insert are designed as passive, high-flow treatment, meaning runoff moves through the media without pumps or electrical components.
Can one insert treat more than one contaminant?
Yes. Because different Smart Sponge® media formulations target different contaminant groups — hydrocarbons, dissolved metals and phosphorus, bacteria, TOC-contributing compounds and PFAS — media can be selected and combined within a single insert or system to address multiple treatment goals identified at the site assessment stage.
What warranty applies to the Ultra Urban® Filter?
The stainless steel version of the Ultra Urban® Filter insert carries a 20-year warranty. This warranty applies to the stainless steel insert itself, not to the filtration media or to other formats such as vaults, skids or booms.
How is the right media chosen for a specific catch basin?
Abtech's process starts with the water: contaminant concentrations, typical and peak flows, available space and effluent targets are reviewed before a media and format combination is recommended. For wastewater and industrial projects, laboratory column testing on the customer's own sample can confirm the fit before full-scale deployment.
Are these inserts a retrofit or new construction only?
The Ultra Urban® Filter is custom-fabricated to fit existing basin shapes, which makes it suited to retrofitting catch basins already in service as well as specifying into new construction.
Facilities weighing a catch basin insert against other stormwater BMPs can review Abtech's stormwater compliance solutions or start with a site assessment to match media and format to the contaminants and permit targets at hand.