IDOT Preliminary Site Investigation (PSI) Project Profile 2024

This project profile documents an IDOT Preliminary Site Investigation (PSI) A3 Environmental Consultants performed as a DBE subconsultant in Schaumburg, Illinois. A PSI is the corridor-scale equivalent of a Phase 2 ESA — if you’re new to the process, start with what a Preliminary Site Investigation (PSI) is and how it follows a Preliminary Environmental Site Assessment (PESA). For a broader look at our IDOT work, see our 2025 IDOT PSI programs across Chicagoland.

Project Overview

This Preliminary Site Investigation (PSI) project, designated under IDOT Job No. D-91-442-20, focuses on assessing potential subsurface contamination across sections of McConnor Parkway in Schaumburg, Illinois. The investigation, covering areas between Meacham Road and Golf Road, seeks to evaluate recognized environmental conditions (RECs) that may impact the construction timeline and worker safety. Weston Solutions, Inc., supported by A3 Environmental, LLC (A3E) as a Disadvantaged Business Enterprise (DBE) subconsultant, leads the PSI efforts.

Project Objectives

The PSI aims to determine the extent and nature of subsurface contamination within soil and groundwater in IDOT’s right of way (ROW) and construction zones. Key objectives include identifying contaminants, estimating contaminated soil and groundwater volumes, and assessing risks of exposure for onsite workers. This investigation will inform IDOT’s strategies for contamination mitigation, safe material handling, and disposal, supporting efficient project completion and safeguarding environmental and public health.

Site Background

This PSI is informed by the Illinois State Geological Survey’s (ISGS) Preliminary Environmental Site Assessment (PESA) Report No. 4358, which identified 16 properties within the project area with potential contamination risks. The PSI prioritizes three properties with significant contamination potential:

1. ROW (ISGS Site No. 4358-30): Located along the IL 53/I-290 and Golf Road ROW, this site has a history of semi-volatile organic compound (SVOC) and metal contamination. Excavation activities, including storm sewer installation, are expected to reach depths of 13 feet below ground surface (bgs).
2. Olive Garden Site (ISGS Site No. 4358-31): This site at 1928 E. Golf Road, formerly containing an underground storage tank (UST) last used in 1972, will undergo excavation for sewer construction at depths up to 7.1 feet bgs.
3. Commercial Building Site (ISGS Site No. 4358-32): A mercury spill in 2006 is noted for this location, and soil management during excavation activities is anticipated for depths up to 7.1 feet bgs.

The PSI will also incorporate subsurface and environmental data from prior investigations and regulatory databases to validate contamination levels across these sites.

Scope of Work

The PSI consists of four main tasks:

1. Background Review and Work Plan Development: Weston Solutions reviewed site data, design drawings, and historical information to establish the work plan’s framework. A site reconnaissance will precede field activities to coordinate utility clearance and optimize sampling locations.
2. Field Investigation: The fieldwork, led by A3E, will involve 11 soil borings using direct-push drilling and temporary monitoring wells if groundwater is encountered. Soil and groundwater samples will be collected, focusing on VOCs, SVOCs, metals, and elemental mercury (for specific areas). Contingency soil borings may be performed if contamination evidence necessitates additional sampling.
3. Laboratory Analysis and Data Validation: Samples will be analyzed by Eurofins Chicago Laboratories for contaminants identified in prior investigations. The analytical parameters will be validated against established regulatory thresholds, such as the Tiered Approach to Corrective Action Objectives (TACO) for Illinois.
4. Reporting and Recommendations: A3E will compile the data into a comprehensive PSI report detailing contamination levels, spatial extent, and recommended mitigation approaches. The findings will inform worker safety measures and disposal strategies for contaminated soil and groundwater.

Health and Safety Considerations

A site-specific Health and Safety Plan (HASP) will ensure compliance with OSHA’s hazardous waste operations and emergency response standards (29 CFR 1910.120). A3E’s Site Health and Safety Coordinator (SHSC) will oversee the implementation of protective measures during field activities, including air monitoring, Level D safety precautions, and verification of personnel training.

Expected Outcomes

The PSI report will provide IDOT with an in-depth understanding of subsurface contamination risks along McConnor Parkway, complete with volume estimates and cost projections for handling contaminated material. Recommendations will address construction worker safety and establish criteria for further investigations if contamination is more extensive than anticipated. By documenting these findings, the PSI aims to minimize delays in construction, protect onsite personnel, and guide IDOT in responsible environmental stewardship.

Frequently Asked Questions

What is an IDOT Preliminary Site Investigation?

An IDOT PSI is a corridor-scale subsurface investigation — essentially a Phase 2 ESA applied to a transportation right of way — performed under IDOT Bureau of Design and Environment procedures to confirm and delineate contamination ahead of construction.

Who performed this PSI?

A3 Environmental Consultants led the field investigation as a Disadvantaged Business Enterprise (DBE) subconsultant to Weston Solutions, Inc., the Prime Consultant, under IDOT Job No. D-91-442-20.

What did the McConnor Parkway PSI involve?

Eleven soil borings using direct-push drilling, temporary monitoring wells where groundwater was encountered, and laboratory analysis for VOCs, SVOCs, metals, and elemental mercury — validated against Illinois’ Tiered Approach to Corrective Action Objectives (TACO).

Planning an IDOT or PSI Project?

A3 Environmental Consultants delivers defensible, schedule-driven field investigations for IDOT and municipal corridor projects across the Midwest. Learn more about our Preliminary Site Investigation services, or call (888) 405-1742.

Reviewed by the A3 Environmental Consultants team, headquartered in Chicago, Illinois, under the supervision of a licensed Professional Geologist (P.G.).