Great Lakes Environmental & Infrastructure (Great Lakes E&I) has successfully completed another In situ Solidification / Stabilization (ISS) treatment project at a former MGP facility on San Francisco Bay. In order to mitigate DNAPL migration into the Bay sediments, exposure to soil and soil gas, and leaching of VOCs, SVOCs, PAHS, and metals from the soil, ISS treatment of the fill/soil and top 3 feet of Bay Mud underlying the former MGP was selected as the remedial remedy. Challenges included operating in a congested industrial area; protecting historic structures; dealing with multiple stakeholders; handling a variety of subsurface obstructions including concrete footers and timber piles; conducting ISS adjacent to bulkheads and saltwater intake structures; and working on a high visibility area of the San Francisco Bay.
Great Lakes E&I utilized 2 RH-28 Delmag drill rigs, 2 automated batch plants, and various sized augers (including one specifically designed to drill through timer pilings) to conduct the ISS mixing. Pilot- and full-scale testing was conducted to develop mix designs tailored to the 3 major treatment areas. Great Lakes E&I installed 790 columns to treat the 26,500 CY of impacted fill/soil and Bay Mud, and used a complex treatment sequence of ISS columns along the bulkhead to mitigate movement of the new sheetpile bulkhead (installed to protect the historic bulkhead). Great Lakes E&I’s robust QA program verified that our ISS treatment met the performance criteria of >30 psi UCS (>100 psi adjacent to the bulkhead), <1×10-6 cm/s permeability, and no unmixed soil or DNAPL in core samples.
By diligently working through project challenges, Great Lakes E&I was able to complete the ISS treatment on time and on budget handling subsurface obstructions, working adjacent to historic structures, controlling odor and VOC emissions below their PELs, and handling excess ISS swell all while exceeding the required performance criteria. Our client is extremely satisfied with our work and looks forward to partnership on future MGP site work.
Please contact us today to find out how Great Lakes E&I can help with your MGP projects or inquire about our ISS capabilities.