Sewer Studies

2018 Sanitary Sewer Evaluation Survey, Final Report

As part of the 2018 Sanitary Sewer Evaluation Survey (SSES) and to satisfy certain legislative requirements, dyed water flooding was completed as a follow-up to smoking storm structures identified during 2017 smoke testing. Dyed water flooding of the storm sewer, performed by RJN Group, Inc. in conjunction with Closed-Circuit Television (CCTV) inspection of the adjacent sanitary sewer, is used to identify locations within the mainline sewer, service laterals, and manholes where the cross-connection is occurring.

Click here to view the full report.

2017 Smoke Testing Program, Final Report

The Village is in the middle of a multi-year effort to identify and mitigate extraneous storm water that inundates the sanitary system, known as Inflow and Infiltration (I/I). Smoke testing is used to detect I/I sources (defects) in the sanitary sewer system. It is a cost-effective method for detecting the existence of private I/I sources, such as downspouts, area drains, cleanouts, and faulty sewer connections, as well as public I/I sources, such as storm to sanitary sewer cross-connections, mainline defects, and manhole defects. This report includes a summary of recommendations regarding the smoke testing services completed by RJN Group, Inc. for the Village as part of the 2017 Sanitary Sewer Evaluation Survey (SSES) program.

Click here to view the full report.

2016 Princeton Basin Dyed Water Flooding Report

In November 2016, RJN worked with Michels Pipe Services to perform dyed water flooding in the Kenilworth Gardens subdivision, to pinpoint locations of inflow and infiltration (I/I) and quantify these flows into the sanitary sewer collection system. These sources of I/I are likely to be significant contributors of I/I to the sanitary sewer collection system.

Click here to view the full study.

2016 North Shore Interceptor System (NSIS) Flow Data Analysis Report

RJN Group, Inc. is pleased to submit this summary of the 2016 flow monitoring program in the Metropolitan Water Reclamation District of Greater Chicago’s (MWRD) North Shore Interceptor System (NSIS) to the Village of Wilmette. The flow monitoring was being conducted as part of a joint project between the MWRD, the Village of Wilmette, the Village of Winnetka, the Village of Northfield, and the Village of Glencoe, and the findings of this study are intended to aid in the analysis of alternatives for alleviating capacity constraints within the NSIS that affect these communities.

Click here to view the full study.

2015 Separate Storm Sewer System Stormwater Management Report

This report summarizes the results of an extensive stormwater management investigation of the Village’s separate storm sewer system located west of Ridge Road. This study, conducted by Christopher B. Burke Engineering Ltd. (CBBEL), focuses exclusively on stormwater management issues and flooding within the western portion of the Village.

Click here to view the full study.

2013 Flow Monitoring Report

This report summarizes the findings from a six-month flow monitoring program conducted by RJN Group between the spring and fall of 2013.

Click here to view the full study.

2012 Separate Sanitary Sewer Hydraulic Modeling

The Village of Wilmette has experienced basement back-ups throughout the separated sanitary system and is looking to make improvements to reduce their frequency of occurrence. The goal of this project was to identify the causes of surcharging in the sanitary sewer and provide recommendations to the City for relieving wet-weather induced surcharging in the system.

Click here to view the full study
(Google account not required to view)

2010 Separate Sewer System Study

The Village of Wilmette has experienced surcharged and backed up sanitary sewers in their separate sewer system west of Ridge Road. This is due to multiple factors, including aging infrastructure and inadequate sewer capacity. The Village hired MWH to execute a screening level assessment of options available to the Village for reducing sanitary basement backups and flooding in the separate sewer system area.

Click here to view the full study.

1990’s Separate Sewer System Study

Since then, the Village has invested millions of capital and maintenance dollars to improve the storm and sanitary collection systems. As a result of the August 23, 2007 and September 13, 2008 storms and many residential sewer system basement backups, it was recommended that a study be conducted to evaluate the current operation of the systems to determine where the Village should focus future resources.

This study will develop an implementation plans and corresponding funding schedule for inclusion in the capital sewer improvement program. This study is one of several multi-faceted strategies to improving the sewer system including development of programs that encourage home owners to protect their properties from chronic sewer backups.

Relief Sewer Project

Existing Sewer System

The Village, with a population of approximately 27,500, is served in the area east of Ridge Road by a combined sewer system and in the area west of Ridge Road by a separated sanitary and storm sewer system. The entire system collects wastewater from approximately 9,000 residential, commercial and institutional buildings and also storm water from approximately 2,500 acres of intensely urbanized area. The combined sewer area is bounded by the Village of Kenilworth on the north, Lake Michigan on the east, the Village of Evanston to the south and Ridge Road on the west.

The combined sewers convey sanitary sewage and storm water runoff from residential neighborhoods through Village-owned east-west trunk sewers to the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) interceptors. Flows travel to the interceptors located along Green Bay Road and Sheridan Road for later treatment at the MWRDGC Northside Water Reclamation Plant on Howard Street in Skokie, Illinois. Storm water runoff exceeding the capacity of the MWRDGC interceptors is conveyed by Village-owned combined sewers to a dropshaft to the MWRDGC deep tunnel under Sheridan Road and the North Shore Channel. Runoff which exceeds the capacity of the deep tunnel overflows into the North Shore Channel.

Previous Studies

Prior to 1990, the Village experienced persistent street flooding and basement backups in the combined sewer area of the Village during rains that were rated a 3-month storm event or larger. In the early 1990’s the Village implemented an aggressive Storm Water Runoff Control Program in an effort to reduce the frequency and severity of basement flooding due to sewer surcharging. The program involves the implementation of a multi-phase improvement project including the construction of over 250 inlet control berms (i.e., roadway storage areas) as well as new interceptor and relief sewers in the combined sewer area.

The first several phases of the Storm Water Runoff Control Program are complete and have reduced the frequency and magnitude of street flooding and basement backups in the Village.