RJN's Knowledge Hub | Inflow/Infiltration

50 Years of Intuition, Innovation, & Insights

Fifty years ago, RJN Group began with a mission to protect public health and the environment, emerging during a transformative era marked by the passage of the Clean Water Act. Over the decades, we’ve grown into a leader in water and wastewater engineering, partnering with communities to deliver innovative and sustainable solutions.

RJN named as BFTWF Company

RJN Group was named to Zweig's Best Firms to Work For Award List for sixth year.

A Model Approach: Accurate RDII Modeling with Antecedent Moisture

RJN modelers have used one relatively new model with promising results compared to more established models: antecedent moisture modeling (AMM)

Three Things You Should Know About MSI

Learn to successfully leverage MSI technologies to evaluate your system’s condition with these three easy steps.

Tips for Navigating the Lead and Copper Rule Revisions

Complying with these new regulations can present unique challenges for water system owners. This article will highlight how communities can effectively navigate the Lead and Copper Rule Revisions (LCRR).

Managing Inflow and Infiltration in Wastewater Systems

One common challenge for all wastewater systems is inflow and infiltration (I/I). By understanding how I/I impacts your system you can safeguard the service life of wastewater assets and ensure sustainable and reliable services for the community. Let's start by unpacking the differences between infiltration and inflow.

Lower Costs with Water Asset Management Best Practices

Embracing a robust and proactive approach to managing sewer, water, and stormwater infrastructure assets can help utility managers improve service reliability, extend the lifespan of assets, avoid failures, and minimize the cost of reactive maintenance.

RJN Named A 2023 Best Firms To Work For Award Recipient

RJN Group Inc. has been named a Zweig Group Best Firms To Work For. With approximately 170 employees spread across offices from Chicago to Houston to Baltimore, achieving this recognition took a tremendous effort from our nationwide team.

Steve Jolley Joins RJN's Senior Leadership Team

Steve Jolley, PE, has joined RJN’s leadership team as vice president of field operations. In this new-to-RJN role, Steve will be responsible for overall field operations.

RJN Announces New Vice Presidents

RJN is pleased to announce that Elizabeth Aguin, PE, and Zach Matyja, PE, have been named Vice President of Operational Support and Vice President of Client Services, respectively.

MSI Drives Rehab Planning for Large Diameter Pipes

Multi-sensor diagnostics used to drive rehabilitation of wastewater pipe

Jeff Griffiths, ENV SP, Joins RJN's East Coast Team

RJN Group, Inc., is pleased to announce that Jeff Griffiths, ENV SP, has joined its team. Serving as the manager of infrastructure assessment, Jeff will work to bring RJN's water and wastewater system evaluations to new markets across the Mid-Atlantic region.

Knowing the What, Where, and When of Storm Water Assets

Building a stormwater asset inventory give the what, where, and when for O&M and capital planning.

Executing Force Main Screening Level Assessments

Screening level assessments (SLA) enable collection system owners cost-effectively evaluate the condition of their force mains.

RJN's Karol Giokas is a Contributing Author of Manhole Rehab Factsheet

Downloadable sanitary sewer manhole rehabilitation resource on materials and methods for renewal.

West Park Five Years Later: Alternatives Analysis Provides Proper Protection

Revisiting the effectiveness of the cost/benefit analysis to alleviate wet-weather sewer system surcharging and create wastewater storage.

RJN Announces Jose Maldonado as Vice President

RJN is pleased to announce that Jose Maldonado, PE, has joined RJN’s senior leadership team as vice president. Jose will now oversee operations for RJN’s Houston office. His promotion to vice president is effective immediately.

When Inflow & Infiltration (I/I) Persists

When you have completed a comprehensive inflow/infiltration (I/I) reduction program, but I/I levels are still not where you want them to be, what’s next? Finding those persistent sources requires diligence and good quality data.

Can Conserving Water During Rain Prevent Overflows? (Part 1)

I recently caught up with an old college friend who mentioned she was refraining from using water during heavy rains so that she wouldn't contribute to overloading the sewer system. It sparked an impromptu lesson on urban hydrology and after hearing similar concerns expressed elsewhere, I thought it was worth sharing my thoughts. No one welcomes beach closings or basement backups, but is abstaining from water use during storms a good way to help prevent sewer overflows? The answer is maybe sometimes, but not really, depending on context. Let me explain.

Kraig Moodie Joins RJN's East Coast Leadership Team

RJN Group, Inc., is pleased to announce that Kraig Moodie has joined its senior leadership team to oversee all East Coast operations. Servings as a regional vice president, Kraig will ensure that RJN continues to deliver on its promise of providing pragmatic and innovative flow monitoring and wastewater system engineering solutions to our clients.

RJN Announces New President and CEO, Paul Costa to lead the firm

RJN is pleased to announce the Board of Directors has selected Paul Costa to serve as RJN’s next President and CEO. Costa, a 30-year industry veteran, assumed the leadership role at the beginning of August 2021.

Case Study: An Award-Winning Emergency Siphon Repair Project

Designing large diameter gravity sewers is challenging. Designing gravity sewers in fully-developed urban areas is even more so.

West Park: Alternatives Analysis Provides Proper Protection

If the last few years have shown us anything, it is that storm events are trending toward the severe end of the spectrum in terms of both intensity and frequency. However, while major storms typically make the headlines as they pose a serious threat to our nation’s communities, sometimes it is the less intense storms that cause the most issues for collection system operators.

Inflow/Infiltration Sources Captured on Video

Inflow/infiltration or clean water entering the collection system can strain capacity and cause overflows. Identifying sources and mitigating those sources through rehabilitation can significantly improve the performance of the collection system. Water seeping into the system through dead laterals, interstitial flow, and leaking connections is often not just seeping as shown in these videos.

Fixing Stormwater's Bad Grade for Current Structural Conditions

On its first American Society of Civil Engineers (ASCE) report card, the nation’s stormwater infrastructure received a D+. While a D+ is not unheard of, as wastewater infrastructure also received a D+, it still does not bode well for our stormwater infrastructure. Flooding issues have compounded as impermeable surfaces increase with development and current systems age beyond their designed service life. Unlike its sewer and water counterparts, stormwater doesn’t benefit from the administrative muscle that can facilitate expedited progress.

Case Study: Large Diameter Lining Project

In 2014, RJN found the City of Joliet had numerous interceptors in poor condition. One of which, the large-diameter Rock Run Interceptor (RRI), was flagged as a high priority due to its proximity to the Rock Run Creek.

Manhole Rehabilitation Specification Tips

NASSCO has elevated and standardized the approach for inspecting sewer assets, both sewers using Pipeline Assessment Certification Program (PACP™) standards and structures using Manhole Assessment Certification Program (MACP™) standards. However, once a structure inspection has been performed, how do you get to a rehabilitation program and develop specifications for bidding?

Can Conserving Water During Rain Prevent Overflows? (Part 2)

In Part 1, this discussion centered on whether conserving water on rainy days could help prevent overflows in separated sewer systems. Combined sewers are the focus of this discussion. By design, combined sewers are significantly larger than sanitary sewers, so in a well-functioning combined sewer system, pipeline capacity is rarely the primary constraint. Instead, it is the capacity of downstream treatment facilities that can easily be exhausted.

The 411 on Preventative Maintenance Programs

So, you reviewed thousands upon thousands of feet of CCTV footage and now you have mountains of data on your sewer system. Great, but now what? How do you take the time, effort, and spreadsheets teeming with information from your CCTV endeavors and turn them into something that works for you? As your fight-or-flight response begins to kick in, take a moment to collect yourself and know that you’re not alone. Now that you’ve recentered yourself and crept back in from the fire escape, our asset management pro, Tristan Nickel, PE, AWAM, has some insights on putting your data to work.

Randy Brodner, PE Joins RJN's Omaha Team

RJN Group, Inc., is pleased to announce that Vice President Randall “Randy” Brodner, PE, has relocated to Omaha to take the helm of RJN's Nebraska-based operations. With 15 years of experience delivering engineering assessment and design services for large and small diameter collection and distribution system pipelines, Randy will bring new perspectives to providing innovative solutions to our Nebraska clients.

Avoiding the Perils of CIPP While Maximizing Its Benefits

So your engineering team has decided to use cure-in-place-pipe (CIPP) to prolong the useful life of the municipal pipelines, but what can the team do to ensure it's successful? Because CIPP programs have become commonplace, it is becoming more prevalent to encounter CIPP lining failures on installations long before the end of their estimated life, oftentimes within the first year of installation. These failures are expensive, frustrating, and completely avoidable.

RJN Announces New Principals: Randy Brodner, PE, & Todd Leistner

At RJN, when individuals demonstrate acute business acumen and an aptitude for leadership, our firm takes notice. With this in mind, we are pleased to announce that Randall Brodner, PE, and Todd Leistner have been named RJN principals.

Asset Management Program Designed to Grow

A case study featuring the development of a water and wastewater utility maintenance program for a growing Texas community originated by RJN's risk analyses.

Avoiding the Perils of CIPP While Maximizing Its Benefits

Best practices for engineering design and construction of cure-in-place pipe, a trenchless rehabilitation technology.

Creative Solutions for a Large Diameter Lining Project

Cure-in-place pipe (CIPP) lining rehabilitation of deteriorated 24- to 30-inch pipe within Illinois DOT rights-of-way and heavily commercialized area.

Sewer Evaluation and Capacity Assurance Planning Minimizes SSOs

A case study for RJN's consent order-driven assessment of the causes of excessive sanitary sewer overflows.

Utility Study Lays the Foundation for Downtown Renewal

Case study of buried infrastructure evaluation and designs for the storm, water, and sewer utilities located in the central business district of Glen Ellyn, Illinois

Wet-Weather Storage Mitigates Recurring Flooding Issues

An initial Comprehensive Flood Control program found that the area served by the Saylor and Jackson pump station was undersized for significant rainfall events.

The Ins and Outs of Upgrading a Large Billing Meter Network

The Massachusetts Water Resources Authority MWRA metering system consists of 212 metering sites located throughout MWRA’s 43 wastewater member communities.

Alternatives Analysis and a 12-Month Design-Build Reduce Overflows

Wet-weather storage capacity improvement project to address surcharge conditions and reduce basement back-ups via design-build.

Building a Comprehensive Stormwater Asset Inventory

A comprehensive video inspection, condition assessment, and rehabilitation program for San Antonio's storm sewer system.

Interceptor Master Planning Produces a Phased Improvement Plan

A case study featuring designs for the Walker-Calloway Interceptor improvements, owned by the Trinity River Authority, Texas.

Valve Study Informs Asset Planning

Engineering case study on the fire suppression system performance and water infrastructure condition throughout the City of Beaumont, Texas

Design of Aerial Crossing Near Power Plant Offers Unique Challenges

Case study of designed improvements to an asbestos cement-bonded, corrugated metal pipe in an aerial lake crossing adjacent to a power plant and a residential area.

Passing of our Founder, Richard J. Nogaj

A tribute article to RJN's founder, Richard J. Nogaj, describes his passing, professional contributions, and his philanthropic efforts.

Case Study: Building a Force Main Assessment Program

A systematic force main inspection and sewer condition assessment program for the maintenance of the City of Naperville's sanitary sewer network.

Case Study: Klefstad Lift Station and Force Main Design

This project was an APWA Chicago Metro Chapter 2025 Project of the Year - Environmental <$5 million category

Case Study: Transforming Joliet: The Path to Sewer System Excellence

This project was an APWA Chicago Metro Chapter 2025 Project of the Year - Environmental $25 - $75 Million

Karen Rico named Regional Director of Infrastructure Assessmen

RJN Group has promoted Karen Rico, PE, to the newly created position of Regional Director of Infrastructure Assessment. This strategic appointment will guide infrastructure assessment operations across Texas, Arkansas, and Oklahoma.

RJN Celebrates 50 Years with a $50,000 Donation

In celebration of reaching the milestone of providing water infrastructure solutions for 50 years, RJN Group Inc., through its philanthropic arm, RJN Foundation, hit another milestone in 2025. RJN Foundation has presented American Rivers, Inc., with a $50,000 grant to support the removal of the Cypress Branch Dam in Millington, MD.

Tristan Nickel, PE, AWAM, Announced as North TX/AR Regional Manager

RJN Group, a leading engineering firm in water infrastructure solutions, is pleased to announce the promotion of Tristan Nickel, PE, AWAM, to North TX/AR Regional Manager. This strategic appointment strengthens RJN's commitment to excellence in wastewater and stormwater management across the South-Central United States.

Case Study: LRWRA Consent Administration

Located on the south side of the Arkansas River, the city of Little Rock’s sanitary sewer system dates back to the late 1800s. The collection system took advantage of the area’s topography to convey flows using gravity, a theme which persists through to today, where approximately 95 percent of the collection system is still comprised of gravity lines. During the last 140 years, the collection system has expanded and matured, now encompassing over 1,400 miles of two- to 72-inch-diameter pipeline, 32 pump stations, and almost 40,000 manholes that convey flows to three water reclamation facilities (WRF).

RJN Group Announces Partnership with SewerAI to Accelerate AI‑Driven Sewer Infrastructure Assessments

We are pleased to announce that RJN Group has formally entered into a strategic implementation partnership with SewerAI, a global leader in AI-driven sewer inspection technologies.

RJN GROUP INC. GUIDES LRWRA TO ACHIEVING CAO COMPLIANCE

A multi-million-dollar collection system improvement program 20 years in the making.

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