Complex, Innovative System Garners Recognition and Achieves Exemplary Performance
Late in 2017, RJN was honored to have its Southwest Wet-Weather Control Facility (SWWCF) for the City of Elmhurst recognized with an Award of Merit in the Small Project (Under $10 million) Category of the ENR Midwest 2017 Best Projects Awards.
The Southwest Wet-Weather Control Facility, serving the southwest area of the City of Elmhurst, is a sophisticated wet-weather flow control system centered around a dry- and wet-weather pumping station that directs flow based on measured flow levels to a dry-weather force main, a wet-weather force main, and a 2.2 million gallon (MG) storage tank located at the City’s Water Reclamation Facility. The primary purpose of the SWWCF is to provide protection to property owners through additional wet-weather capacity, mitigating recurring basement backup issues.
And it has proven to do that and more—the SWWCF has been a tremendous success as recent reports from Patch find that according to the City, the new excess flow tank for southwest Elmhurst was activated and diverted almost 2 million gallons of wastewater during a significant rain event on Saturday, October 14, 2017.
Designing and constructing the multi-faceted wet-weather control facility required careful planning to develop a sound basis of design for each of the intertwining components and to structure a phased construction plan that ensured sanitary sewer services would not be interrupted. In addition to using innovative techniques and materials, such as a specialized 18-inch Certa-Lok restrained joint pipe, the search for which is profiled in this prior blog feature, RJN also used in-depth analysis to develop the best solutions for each component.
Each of the SWWCF elements was designed as a separate component using system design flow requirements developed using collected flow data, quantified I/I source contributions, and hydraulic modeling to size lift station and force main pumping and discharge capacities. Design of each facility component vetted various alternatives to ensure design capacity, investigating different construction methods, routes, and construction limitations, balancing ongoing maintenance needs to ensure the most cost-effective, long-term solution.
Dry-Weather Force Main
The existing connection to the City’s main McKinley interceptor was relocated to discharge to a manhole where the interceptor transitions from 36 inches to 48 inches to limit the potential of surcharging.
Wet-Weather Force Main
Sizing was relatively straightforward; however, finalizing the route proved to be a challenge. Since the force main was being installed in a mature, developed residential area with a creek crossing and existing utilities, considerations such as available right-of-way and soil conditions were critical aspects of the alignment and drove the selection of routing, construction methods, and materials.
Lift Station Upgrade
With the addition of the wet-weather force main, installing three wet-weather pumps in a triplex system allowed the pumps, when activated, to operate with either one or two pumps. However, the extended pumping capacity did require additional wet-well volume. The solution was to add a new interconnected wet-well adjacent to the existing station.
Detention Storage Tank
The required volume of detention storage was determined by modeling to simulate 25-year design storm conditions. As a result, it was determined that substantial benefit would be gained by increasing the detention storage to 2.0 MG.
Based on the work put into designing this successful system, it is easy to see why it has proven itself successful during a recent rain event—and why it has earned an award of merit. But how did ENR Midwest determine the awardees? According to ENR Midwest’s blog, “Every year, ENR Midwest assembles independent judges from architecture, engineering, and construction firms in the area. After an initial scoring of projects, the judges—via two separate panels—met via teleconference to discuss the projects and come to a consensus on awards. Judges could select any combination of Best Project-level category winners and Award of Merit honorees.”
And, of course, ENR Midwest recognizes and appreciates the fact that many of these impressive projects required productive collaboration between firms. For the SWWCF, the project team was assembled as follows:
RJN Group, Inc. is proud to have its engineering recognized with this prestigious honor.