Appendix G: Expert Interview Summary

Interview Type: Expert Witness

Interviewees: Mark Richards (Vice President and Director of Engineering at Webster McGrath & Ahlberg, Ltd.)

Interviewers: Michael Richards

Purpose: Gain Initial Project Partner Feedback on Mockups

Project: Green Bay Trail Beautification Project

Date: May 10, 2021

Location: Phonecall

On May 10, 2021 at 7:30 pm, Michael Richards conducted an interview over the phone with Mark Richards, Vice President and Director of Engineering at Webster McGrath & Ahlberg, Ltd., who acted as a civil engineering expert witness for the design project. The meeting lasted approximately one hour. In preparation for the interview, Michael obtained topographic maps and images of the area, as well as the project definition, and emailed them to the civil engineer. In the interview, the civil engineer outlined the key problems associated with the GBT and his proposed solutions, based on previous projects his firm had undertaken. The meeting is transcribed below.

Assessment of the Trail:

After viewing the topographic maps, pictures of the trail, and the project definition, the civil engineer concluded that the GBT was definitely an afterthought included beside the moved railroad. He also explained that the scope of the solution will have to be very broad due to the nature of the partner, intended budget, and size of the project.

Identified Problems:

The civil engineer’s first concern was with regards to the intended budget. $100,000, as raised by Glencoe for their restoration of the GBT, is more than enough to resolve the invasive species problem and reintroduce native species, but not nearly enough to implement a comprehensive hardscape solution to resolve drainage problems. Glencoe’s restoration was largely a landscape engineering project, whereas after reviewing the project definition, the civil engineer believes that there is definitely a need for a civil engineering approach to Winnetka’s restorations–and this sort of approach easily fetches well over $100,000. In fact, televising the drains to complete a thorough, yearly inspection will cost approximately $2000 per year, replacing/adding catch-basins to the storm inlets and structures will cost $1500 per inlet, and implementing retaining walls will cost approximately $30 a face foot. He did note that using blocks rather than cement will be cheaper.

Another concern of his was with regards to the state of the retaining walls and pitch of the slope down to the trail. After viewing the topographic map and the pictures taken of the trail, he acknowledged that the pitch of the topographic elevation change was definitely a culprit in the amount of stagnant water and erosion observed near the trail. He found the state of the existing cement retaining wall to be acceptable, but the wood retaining wall was in disrepair and needed to be replaced with either cement or block immediately. He was shocked that wood would ever have been used in the retaining wall to begin with, as its tensile strength is not up to par to support such a large change in elevation. He also explained that in the implementation of a retaining wall, it might be necessary to consult a structural engineer.

Based on the pictures taken, he concluded that the trail’s deterioration can be best attributed to lack of maintenance. This is also why he believes stagnant water has become such an issue beside the trail. The amount of invasive species in the area is definitely a contributor, as invasives and weeds often have very shallow roots which do not support the ground or help absorb the stagnant water. Native species, on the other hand, have roots which can extend up to 10ft underground, have the added benefit of naturally resolving drainage problems by strengthening the soil and absorbing stagnant water. Additionally, he was surprised that ditches were being dug leading to the drains. In order for water to effectively drain, there needs to be a positive slope with minor grading extending from the drains and other storm inlets. Digging a ditch without proper grading will only add to the problem. Most of all, however, it is clear that annual drain inspections are not being conducted, which is dearly needed to ensure proper draining over the long term.

Proposed Solutions:

The civil engineer was a fan of the tiered retaining wall proposal, but noted that due to its cost, it will have to be included as part of a tiered list of solutions. As far as materials, he preferred using blocks due to a cheaper cost when compared to cement. It will cost approximately $30 a face foot, including the foundation behind it. He also explained that regardless of the other components of the solution, minor grading must be done in order to ensure that there is a slope of about 1% pitching towards the storm inlets and an annual inspection of the drains must be conducted by televising the pipes for about $2000 a year to keep them up to par with standards and regulations. Additionally, the design solution could include adding catch-basins to the storm inlets at a cost of about $1500 per inlet to collect unwanted material from flowing into the storm inlets to prevent clogging, prolong the lifespan of the drainage system, and simplify maintenance of the drains by allowing material to be removed from the catch-basin as opposed to being dug out from the bottom of the storm inlet. Though this is more relevant to the other GBT team’s project definition, he also advocated for the use of native species to address the stagnant water.

As part of his advice for proposed solutions, the civil engineer advocated for a tiered approach to the solution, ranging from a “Band-Aid” (low-cost) solution to a “Cadillac” (high-cost) solution. He explained that this approach is often used when working with cities whose budget often depends on community approval. As a result, his firm can explain what is needed to fix the problem, which is often more than the city is willing to spend on the project, as well as what is needed to prolong the problem, which is often well within the city’s budget. He explained that the city or our project partners will often choose a middle-of-the-road solution which still conforms to their budget. In the GBT beautification project, the civil engineer recommended design proposals ranging from inspection at the low-cost end of the spectrum to full construction at the high-cost end of the spectrum.

In his solution proposals, the civil engineer also encouraged the team to be cognizant of the regulations and standard practices followed in the field. Make sure the path follows a 1.5-2% grade across, in order to conform to ADA regulations. The standard today has shifted to complying with Best Management Practices (BMPs) wherein environmentally friendly practices are used whenever possible to maintain rate control. This is done in order to preserve the natural groundwater supply of the region, and so the goal has shifted to practices which transfer as much water back into the ground as possible. There are added benefits to doing this, as the water quality will always benefit due to the natural filter of the ground which pulls pollutants out of the water.