March 14, 2016The City of Virginia Beach, Va., has been addressing pesky and costly inflow-and-infiltration (I/I) issues that had been plaguing its wastewater system for many years. Under terms of a consent order, city officials put together a comprehensive rehabilitation plan that included attention to its manholes. Because of this, the City has seen a significant improvement in its problem areas.
Stephen T. Motley, P.E., is the regulatory compliance bureau manager with the City of Virginia Beach Public Utilities. The City had initially installed plastic inserts to block the inflow coming in through its manholes. However, that did not solve the problem and the City looked for a new solution. In 2008, after dealing with the failing inserts and continued I/I issues, the City turned to stainless steel Rainstopper Manhole Inserts to be installed in 250 identified basins. The switch provided much better results, in terms of rehabilitation costs and I/I headaches.
Rainstopper Manhole Inserts are manufactured by Southwestern Packing & Seals and distributed by WBE Dorcas Inc. For this project, the inserts were installed by Hydrostructures P.A., of Virginia Beach, Va.
“We had historically begun using plastic inserts and they were problematic for several reasons, so we moved to the stainless steel Rainstopper inserts and saw immediate results,” Motley says. “Initially, the inserts were installed in the low lying basins, but we found they are a benefit regardless of their location, so as we perform SSES work now, we install them in every manhole, including all new manhole installations.”
Those immediate results observed by Motley on this project were published in Virginia Beach, Va.’s “Water Jam 2008,” an abatement study conducted from Sept. 7 – 11, 2008, in which data reported the immediate inflow reduction as the result of installing the inserts.
According to that abatement study, part of the City of Virginia Beach, Va., rehabilitation plan included identifying 400-plus stations in the City — approximately one third of which were identified with having excessive run times and underwent further analysis. The analysis included smoke testing, dye testing/flooding, CCTV inspection and hydraulic analysis of the pump station. It was estimated that 85 percent of the stormwater inflow sources encountered are from faulty laterals, the study said. The recommended means to reduce stormwater inflow through manhole covers and access cleanouts included installation of mainline and property line cleanouts and Rainstopper manhole inserts. A “find-and-fix” approach was used to gain immediate wet weather flow reduction by remediating inflow sources as they are discovered.
By using Supervisory Control and Data Acquisition (SCADA) information, pump stations with excessive run times and areas with high service calls were identified, and the City was able to evaluate and rank each pump station service area for apparent stormwater inflow magnitudes. A significant reduction in flow to each station was experienced after the installation of cleanout plugs and manhole inserts.
Fast forward to 2015. Brown and Caldwell published “City of Virginia Beach Rehabilitation Plan: Peak Flow Reduction Analysis for I/I Abatement Measures.” This study was done on 41 of the 275 of Virginia Beach’s 408 service areas in which Rainstoppers are currently installed. Data collected reported the following:
• Average pre inserts and plugs 10-year peak flow: 543 gpm
• Average post inserts and plugs 10-year peak flow: 384 gpm
• Average 10-year peak flow reduction per service area: 159 gpm
The report’s results reaffirmed what Virginia Beach officials already knew about the improvement to the City’s I/I situation. “The installation of Rainstoppers has exceeded all our expectations in reducing inflow. We knew it would have some benefit, but we continue to see benefits all the time,” Motley says.
Motely says there are 250 basins listed in the City’s consent order, with eight basins being addressed a year. Currently, approximately 6,000 Rainstoppers have been installed and eventually every manhole in Virginia Beach will have one.
An interesting example Motley recounted was the fats, oils and grease (FOG) program having an issue with grease at a pump station. Crews could not determine where the grease was coming from, as there was no grease present upon inspection. What they discovered was during a rain event, the grease from the roof runoff from a building was entering the manholes. The City installed six Rainstoppers and one cleanout plug, solving the problem. Motley explains that this is one of the many benefits of installing the manhole product.
“It is a simple and cost-effective solution. You would spend much more money trying to find the problem and determining the cause of the I/I, when installing inserts and plugs solves the problem. We are doing investigation work faster than the construction can keep up. We get asked, ‘Why don’t you slow down?’ And we reply, ‘The Rainstoppers are why we don’t slow down.’ It is an immediate benefit that can be realized much quicker than anything else you can come up with.’
Where does the project stand today? Motely says there are 250 basins listed in the City’s consent order, with eight basins being addressed a year. Currently, approximately 6,000 Rainstoppers have been installed and eventually every manhole in Virginia Beach will have one. With a 50-year protocol projected, that is a successful project for this city, he says.
Southwestern Packing & Seals Inc. has spent the last 35 years providing municipalities an effective tool that prevents additional inflow from entering wastewater systems, enabling municipalities to produce revenue through saved wastewater treatment costs. Rainstopper models include HDPE, stainless steel and Tetherlock to prevent inflow, and the Life Saver model, which in addition to preventing inflow, also prevents unauthorized entry through its patented locking system.
Through Virginia Beach’s “find-and-fix” program, the City reduced inflow in its system, saved wastewater treatment costs and is an excellent example of a city that takes its I/I abatement approach seriously. There is no better proof of the effectiveness of a product than collected data.
“The peak flow graph says it all. It is a great example of utilizing a quality product that gives you the biggest bang for your buck,” Motley says.
Dorcas Neatherly is president of WBE Dorcas.