October 26, 2021
Coming in at no. 58 in our countdown of Epstein's Top 100 projects is 353 N. Clark, a 45-story, 1,450,000-square-foot high-rise office building at Kinzie, Clark, Dearborn and Carroll Streets in Chicago.
For 353, Epstein served as architect of record and structural and civil engineer. We also provided graphic design services for this project, which serves as the new corporate headquarters for the diversified financial services firm of Mesirow Financial and the national law firm of Jenner & Block LLP. Epstein worked in association with the design architect, Dirk Lohan, and features over 1,300,000 square feet of office space, 25,000 square feet of retail space, and a 180-car parking garage.
353 N. Clark, which is certified LEED-CS Gold, features numerous sustainable design elements, including a stormwater management plan that results in decreased quantity of runoff from calculated pre-project conditions. In addition, the heat island effect is reduced through a 58% vegetated roof. The installed irrigation systems also reduce potable water consumption by 100% and total water use by 78% from a calculated baseline case.
The civil project scope for 353 included the design of two sanitary sewer connections to the City of Chicago public sewer, dual water main services for the building domestic and fire protection systems, and a stormwater management system that included rooftop detention, underground detention, and rainwater harvesting for the irrigation system. Both the stormwater detention and rainwater collection design were applicable for LEED credits. The site posed challenges for the grading due to a change in elevation of nearly 13 feet from the north side of the site to the south. The project was also required to meet existing grades along the elevated Carroll Street bridge structure along the south side of the site. Detailed grading plans were prepared that achieved the required ADA accessible routes around the entire building while maintaining workable elevations at every building man door and rollup door location. The adjacent roadway pavement and gutter elevations were slightly modified to bring the street drainage in compliance with the minimum CDOT criteria.
In addition, our structural engineers were dealing with a site that was the location for various buildings during the past 100-plus years. There was not any documentation for those buildings; hence, there were numerous existing foundation systems and other obstructions that needed to be identified and located. The foundation system for the new building supports heavy loads due to the height of the building and this new and substantially proportioned foundation system was designed to avoid the existing underground obstructions, which placed some special demands upon the design. An earth retention system had to be designed to enable construction of two subgrade levels for the building while maintaining the integrity of the adjacent streets and adjacent construction. Some of the adjacent construction included elevated roadway, existing earth retention systems, ComEd electrical vault, and vaulted sidewalks.
The City of Chicago once utilized underground water tunnels and underground freight tunnels, which have since been abandoned. Both of these types of tunnels traversed across the site. The designers had to determine the location of the tunnels, bulkhead the tunnels at the property lines, and design a foundation system that spanned over the tunnels without disturbing them during or after construction. The project site is very close to the Chicago River. For that reason, subgrade water pressure and mitigation strategies were critical design considerations.
As is typical in the Chicago area, there is a hardpan clay stratum approximately 75 feet below existing grade that overlays a water bearing granular stratum. The granular stratum is over bedrock. The hardpan clay stratum provides good bearing capacity and also provides an effective seal from the water pressure from the underlying granular stratum. One of the historical buildings that was once on the site used hand-dug rock bearing caissons that penetrated the hardpan clay. Those existing caissons effectively breached the water seal that the hardpan clay typically provides. That required special caisson designs and construction considerations for the new foundation system to circumvent water related problems emanating from below the hardpan clay stratum.