Penetron Adds Durability to Innovative Illinois Wastewater Filtration System

The successful commissioning of the Primary Filtration System in December 2023 by the Four Rivers Sanitation Authority (FRSA) in Rockford, IL, provides the FRSA sewer network with key efficiency gains to help meet EPA guidelines. PENETRON ADMIX SB, a crystalline concrete waterproofing admixture, was specified to protect all new concrete structures from the aggressive environment of the stormwater runoff and untreated effluent – maximizing the service life of the new wastewater treatment system.

Serving over 290,000 people in the communities within Winnebago County in northern Illinois, the Four Rivers Sanitation Authority (FRSA) owns and maintains a 1,126-mile network of gravity sanitary sewer lines. This network transports wastewater from residences, industrial sites, and other establishments to the wastewater treatment plant in Rockford, IL.

It also gives concrete the ability to self-heal and seal any micro-cracks that may occur in the future, minimizing the need for future waterproofing-related concrete repairs.

Pat O’Brien, Regional Sales Manager for Penetron USA

In 2022, the FRSA mandated the implementation of the Rockford Primary Filtration project to enhance primary solids removal capabilities and replace local facilities that had exceeded their service lives. Rather than using a primary clarifier, a Primary Filtration process uses a pile cloth-depth filter (PCDF), which is used after screening and grit removal prior to the activated sludge process.

“A relatively new wastewater treatment innovation, the Primary Filtration enhancements also improve the performance of the Rockford wastewater treatment plant, to run more efficiently and meet guidelines set by the federally mandated National Pollutant Discharge Elimination System (NPDES) program,” added O’Brien.

The Rockford Primary Filtration project was completed by Williams Brothers Construction, the general contractor, and comprised:

  •     Four primary filtration influent pumps located in a wet well
  •     Two primary cloth media disk filter units with backwash pumps, waste solids pumps, valving, and piping
  •     Gravity thickener with two primary filtration thickened sludge pumps
  •     Scum pump wet well with a scum pump
  •     Primary filter effluent flow split structure

“After reviewing the Primary Filtration project specifications with the local Penetron representative, Rogers Redi Mix, the ready-mix concrete supplier, opted for PENETRON ADMIX SB as the most durable concrete waterproofing solution,” said O’Brien.

About 2,000 cubic yards of PENETRON ADMIX SB-treated concrete mix was used for all concrete structures exposed to stormwater run-off and effluent. Delivered in pre-measured soluble bags, PENETRON ADMIX SB is added to the concrete mix during the batching phase. Once part of the mix, the admixture creates a non-soluble crystalline network, which forms throughout the pores and capillary tracts of the concrete to reduce concrete permeability and increase resistance to the chemicals and aggressive compounds found in wastewater.

“PENETRON ADMIX SB significantly increases the durability and service life of concrete structures,” concluded O’Brien. “It also gives concrete the ability to self-heal and seal any micro-cracks that may occur in the future, minimizing the need for future waterproofing-related concrete repairs.”

The Penetron Group is a leading manufacturer of specialty construction products for concrete waterproofing, concrete repairs, and floor preparation systems. The Group operates through a global network, offering support to the design and construction community through its regional offices, representatives, and distribution channels.

For more information on Penetron waterproofing solutions, please visit or