Professional Geotechnical Engineering Services for Laureldale Avenue at 105 Freeway

The City of Downey seeks proposals from qualified Geotechnical Engineering Consulting firms to investigate and analyze a pavement subgrade failure located on Laureldale Avenue, adjacent to the I-105 Freeway bridge abutment. The settlement of subgrade material beneath the street, curb, gutter, and sidewalk has caused persistent pavement deterioration and structural damage. Specifically, pavement settlement has led to recurring potholes in the roadway, and the sidewalk and gutter have cracked and separated from the curb. The City suspects that the settlement may be related to an underlying drainage pipe situated along the face of the abutment, covered with crushed rock backfill. This aspect should be explicitly investigated during the study and a closed-circuit television (CCTV) inspection of this pipe shall be included in the investigation. The selected consulting firm shall provide comprehensive geotechnical engineering services, including but not limited to:• Conducting subsurface explorations (soil borings and/or test pits) with a minimum of three borings advanced to at least 15 ft below existing grade—or two feet into competent material, whichever is deeper—to characterize existing conditions.• Evaluating the drainage system adjacent to and underlying the abutment, including CCTV inspection, in-place hydraulic conductivity testing of the crushed-rock backfill, and assessment of its influence on subgrade stability.• Performing laboratory testing of soil and material samples to determine engineering properties and suitability.• Analyzing collected data to clearly identify the cause(s) and full extent of the subgrade failure, including consolidation, immediate elastic settlement, global slope stability, and long-term differential movement between the pavement, curb, and bridge abutment.• Providing feasible engineering recommendations for stabilization and mitigation measures to correct existing settlement issues and prevent future subgrade failure, including any necessary modifications to existing drainage infrastructure.• Offering construction methodology recommendations and specifications for recommended remediation measures.Please ensure your proposal includes the following components:1. A detailed scope of work outlining each task to be performed, clearly identifying methods of investigation, testing, and analysis (and pricing any optional services such as ground-penetrating radar or seismic CPT separately).2. A project schedule delineating all key milestones, deliverables, and proposed timelines.3. Qualifications, relevant experience, and credentials of your firm and key personnel to be assigned to the project.4. A detailed fee proposal specifying the Not-to-Exceed amount, hourly rates, estimated labor hours, and itemized breakdown of anticipated costs for each task.5. Assumptions, exclusions, and clarifications relevant to the scope of work and pricing.