MetroLink Slope Stabilization
CLIENT: St. Clair County Transit District & Bi-State Development
TWM provided slope stabilization design services and assisted St. Clair County Transit District with the grant application, which resulted in $6.5 million in State funding being awarded for multiple phases of this project. For the first project under this grant, TWM prepared an analysis of a 30’ high x 200’ long soil nailed retaining wall immediately adjacent to active MetroLink tracks, which was showing signs of distress. After an in-depth structural and geotechnical analysis, it was determined unsafe for the wall to remain due to ground water levels that were much higher than the assumed level in the original design. In partnership with MetroLink, the wall was prescriptively demolished and the hillside cut back to a 3:1 slope. The work was done adjacent to active tracks under flagging protection. TWM prepared the plans and specifications for the project, provided construction observation, and negotiated the easements/ROW. This portion of the project was completed in 2011.
The second project utilizing these grant funds included 29 additional erosion mitigation sites along the MetroLink alignment in St. Clair County. TWM prepared the plans for the design, repair, reinforcement and construction of retaining walls and structures, re-vegetation, soil remediation, soil strengthening for greater slope/culvert protection, replacement or repair of existing drainage systems, ballast retainers at junction boxes, and additional 1.5 miles of gravel access road. As in the first project, TWM coordinated with adjacent property owners for all easements and negotiated ROW.
TWM staff also provided construction phase services, such as weekly reports and meetings; photo logs; communication with SCCTD, MetroLink, and the Contractor; coordination of contractor’s weekly railroad Work Permits, Job Hazard Analysis submittals, and other safety management items. Additional services included providing staking and layout, earthwork inspections, coordination of material testing with an outside firm, quantity measurement/verification, material certifications, pay estimates, documentation, and compliance with the railroad procuring department.