The Addison Creek Channel improvements and the reservoir projects are part of a larger project by the MWRDGC to address regional stormwater problems in Cook County consisting of six major watersheds covering approximately 730 square miles. INTERRA performed Phase I Environmental Site Assessment (ESA), Phase II Environmental Site Assessment and Geotechnical Subsurface Soil Exploration to aid in the design of various reaches of the project.

The Phase I ESA was conducted in general accordance with the American Society for Testing and Materials Standard ASTM E1527. As a part of the ESA, several documents including Historical Topographic Maps, Aerial Photographs and Sanborn Fire Insurance Maps were reviewed. Additionally, various Federal and State Databases were reviewed. Site reconnaissance was also conducted as part of the Phase I ESA to verify the findings of historical document review.

The Phase II ESA included drilling, soil and sediment sample collection for analytical testing.  The findings of Phase I ESA were used to determine the analytical parameters.  The analytical test results were used to determine the Soil Management options which included in-place management of soils, disposal at Clean Construction and Demolition Debris (CCDD) facilities and disposal of soil and sediment as Non-Special waste.

Geotechnical investigation included numerous soil borings, extensive laboratory testing and slope stability analyses to evaluate the stability of existing slopes, design various new soil retention systems and to provide recommendations for foundations of various structures that are part of the channel improvement project. INTERRA also assisted in the preparation of construction contract project specifications and bid documents.