Project Features:
- 10,000 CY of Excavation & Demolition
- 18,000 Tons of Soil & Debris Disposal
- 76 LF Soldier Pile Lagging Wall
- 560,000 Gal. Water Treatment
- Water Line & Sanitary Sewer Relocation
- 18,000 CY of In-situ-Stabilization (ISS)
- 14,000 Tons of Backfill & Topsoil
Description of Work:
Geo-Solutions completed the remediation of a former manufactured gas plant (MGP) site in Manitowoc, Wisconsin. The site is a 2-acre parcel located within city limits and adjacent to the shoreline of the Manitowoc River. The work spanned both sides of Chicago Street, requiring Geo-Solutions to close one full block to all public traffic. As the prime contractor, Geo-Solutions was responsible for all elements of the project including site preparation and controls, excavation, demolition, in-situ solidification / stabilization (ISS), and site restoration.
The primary remedial goals of the project called for the demolition and excavation of two (2) former gas holder foundations, and ISS treatment of coal tar impacted soils in several adjacent portions of the site. Both tasks were complicated by the layout of the site which included off-camber slopes and retaining walls in various orientations descending from Chicago Street down to the river. The subsurface work also required significant excavation and removal of former building foundations, MGP remnant structures, and process piping.
Geo-Solutions excavated, cleaned out, and demolished both concrete holder foundations and removed over 18,000 tons of contaminated soil, concrete, and debris. One area required a temporary soldier pile lagging wall adjacent to an active commercial property to support the building during a holder demolition and soil removal.
The ISS work was completed with our Casagrande B360 drill rig using 8’ augers in multiple work areas, all of which had complicated geometry, subsurface obstructions, and treatment depths varying from 20 to 45 feet below grade. In total, over 18,000 CY of contaminated soil was treated by ISS.
High groundwater near the river also required significant excavation dewatering and on-site water treatment with our 200-gpm mobile treatment plant. Over 560,000 gallons of water were treated and discharged to the POTW.
Final restoration of the site included complete restoration of the disturbed portions of Chicago Street (asphalt paving, concrete sidewalk and curbs, storm sewer, and water line). A new site grading plan covered the entire lower half of the site to create a gradual grassy slope to the river which will eventually become a town park.
