On January 24, 2017, the Village Board approved a Value Engineering Review of the Separate Storm Sewer System Study west of Ridge Road, completed in 2016. The contract was awarded to Chicago-based MWH-Stantec. Click here to read the complete proposal.
Stantec was asked to verify and validate the proposed project’s costs and associated benefits. Stantec concurred with the conclusions of the Burke study regarding the effectiveness of the project, while also noting that the project could cost as much as $95 million (in 2017 dollars). Stantec determined that the value engineering review of the $80 – $95 million improvement project did not identify options to dramatically reduce the cost of the project. Refinements in design criteria and implementation strategy could provide cost savings on the order of 5% – 10%.
In June 2017, to ensure that all alternatives and lower cost options were considered, the Village tasked Stantec with exploring all possible options to reduce the depth and duration of overland flooding west of Ridge Road. The feasible project alternatives range in cost from $48 – $95 million (in 2017 dollars) and provide varying levels of flood protection.
The consulting firm of Christopher B. Burke Engineering Ltd. (CBBBEL) was engaged to perform the study in 2014 after several large rain events resulted in widespread overland flooding. The study began with public engagement to learn about residents’ flooding experience and was followed by a comprehensive hydraulic and hydrologic modeling of the storm sewer system. The analysis by CBBEL indicated the bottleneck in the system is the network of storm sewer pipes, because they are not large enough to efficiently convey stormwater to the pump station on Lake Avenue. As a result, there is system surcharging and overland flooding during even moderate rain events.
CBBEL presented a series of alternatives that would achieve the Village’s goal of flood protection during a ten-year storm event. The results of the study and alternatives to address the problem were discussed at a series of Municipal Services and Village Board meetings in 2015 and 2016. Through these meetings, it was determined that building relief sewers to add capacity to the existing storm system would provide the greatest benefit. Known as Alterative 1, this project consists of building approximately 44,000 feet of new sewer pipe and would cost an estimated $77 million.
Given the significant financial investment and impact of this proposal, the Village Board budgeted $120,000 in the 2017 budget to hire an independent consultant to review and confirm the results of the CBBEL study.
Main Objectives of the Study
- Determine if the original data collection was reliable and adequate.
- Verify the existing storm sewer network limitations, the hydraulic model results, and system bottlenecks.
- Evaluate Alternative 1 and identify potential changes to the project that would provide the desired level of service at lower capital outlay.
- Review the methods, assumptions, and calculations used to develop the initial cost estimate for Alternative 1.
Meet the Consultant
After carefully reviewing multiple proposals, the Village Board awarded the contract for the Value Engineering Study to Chicago-based MWH-Stantec (MWH). MWH has previous experience working with Wilmette’s sewer system, and extensive knowledge and experience in wet weather management for many similar communities, including Winnetka, Glenview and Evanston. The MWH project manager assigned to the project, Joe Johnson, has more than 30 years of experience in the planning, analysis, design and construction of stormwater management projects. Mr. Johnson was also instrumental in developing master stormwater plans in Glenview, Winnetka, Des Plaines, Arlington Heights, Chicago and Rockford, among others.
In their proposal, MWH exhibited clear understanding of the Village’s reason for commissioning this independent review of the CBBEL study. Their overarching goal is to provide the Village Board, staff and the entire community with confidence, should the Village Board choose to move forward on a stormwater project. One of the most critical components of the Value Engineering Study is the cost review. MWH has devoted construction experts from both in-house staff and Berger Excavating (an underground pipeline contractor) to evaluate all aspects of the project. One of the key staff, Robert Magna, works for MWH Constructors and has 36 years of construction estimating experience. Staff has confidence that the team of professionals devoted to this project will produce a thorough, accurate and comprehensive report at the conclusion of the study.