RCRA Remedial Construction
Former HoltraChem Manufacturing Facility
Orrington, ME
Provided geotechnical review and construction oversight services to Maine DEP related to deep soil removal as part of site remediation activities at a former chemical manufacturing facility having mercury as the primary contaminant of concern.
- Review services included evaluating and commenting on a petition to limit the scope of contaminated soil removal in a portion of the remediation site.
- Oversight services included reviewing design and construction documents for the support-of-excavation and dewatering systems for a deep excavation necessary to remove contaminated soils, as well as excavation sequencing and geotechnical monitoring. On-site services were provided during sheet pile, deadmen and helical anchor tieback, and waler installation, and subsequent soil excavation.
SchonewaldEA retained by TechLaw (Remediation Oversight Contractor for Maine Department of Environmental Protection)
Geotechnical Instrumentation & Stability Assessment
Berm Constructed Over Soft Organic Soils
Colebrook Municipal Landfill
Colebrook, NH
As part of the required landfill post-closure monitoring program, implemented an instrumentation program to monitor the post-closure movement of a landfill perimeter berm that had been constructed over soft organic soils in order to assess the berm’s stability.
- Developed the work plan for the stability monitoring program for review by the New Hampshire Department of Environmental Services.
- Completed test borings and installed slope inclinometers at key locations through the berm of concern.
- Collected, reduced and interpreted the slope inclinometer monitoring data.
- Prepared a final report documenting the stability monitoring program, evaluating the monitoring data in aggregate, and commenting on the overall stability of the berm.
Evaluation of the monitoring data considered the full depth profile (shape) of the inclinometer casings over time, and focused on the observed strain rate within the organic layer, with consideration given to the natural processes of secondary compression and creep.
SchonewaldEA retained by Casella Waste Management
Design and Permitting Support Services
Compacted Clay Barrier Layer Borrow Area Approvals for Crossroads Landfill
Norridgewock, ME
- Developed final design for a new on-site soil borrow area for compacted clay barrier layer material for landfill construction. Design specified depths to which material meeting the low-permeability requirements could be borrowed, as well as site restoration grades.
- Prepared permit application package including NOI to Maine DEP, public notice, and abutter notifications.
SchonewaldEA retained by Waste Management
US-EPA Superfund OU1 Remedial Action
Former Callahan Mine
Brooksville, ME
Teamed with prime engineer to the OU1 remedial action contractor to complete a comprehensive geotechnical investigation and stability analyses of the former mine waste (tailings) impoundment that was constructed over soft silt-clay. Objective of the work was to develop baseline geotechnical conditions, assess hydrological conditions within the impoundment, evaluate global static and seismic stability and liquefaction potential of the tailings impoundment, and support the relocation of ore pad waste to within the tailings impoundment footprint.
The geotechnical investigation consisted of completing:
- Field Explorations: test borings and vibratory piezocones, sampling the tailings and underlying soils, in-situ soil (strength) testing
- Instrumentation: overburden and bedrock wells, vibrating wire piezometers
- Laboratory Analyses: tests to assess index properties, stress history, consolidation properties, strength parameters of the tailings and the soft silt-clay underlying the site
- Analyses and Report: compilation of data, selection of key stability sections, development of subsurface profiles including shear strengths and hydrological conditions, assessing liquefaction potential, evaluating static and seismic stability of the existing conditions evaluating the stability of certain OU1 remedial actions, preparation of a summary report
SchonewaldEA partnered with and provided field and technical/QA support to Credere LLC, who served as lead investigator for this work
US-EPA Superfund OU1 & OU3 Remedial Action
Former Callahan Mine
Brooksville, ME
SchonewaldEA provided geotechnical engineering support to the Maine Department of Environmental Protection’s OU1 and OU3 prime consultant (CES, Inc.)
Work during the OU1 phase of work for CES/Maine DEP included stability analyses, as well as design and construction support for an on-site disposal cell. The cell was for disposal of on-site low-level PCB contaminated soils. It was constructed abutting and over a portion of the tailings impoundment.
Work during the OU3 phase of work for CES/Maine DEP included geotechnical support associated with CES’ design and installation of a horizontal drain through the base of the tailings impoundment perimeter berm. The drain was intended to lower the water level within the tailings and thereby enhance the overall stability of the tailings impoundment.
SchonewaldEA retained by CES, Inc.
