City of Torrance Airport and Commercial Property Site Investigations

Terraphase was engaged by the city of Torrance in California to investigate soil, soil vapor, and groundwater impacted with chlorinated volatile organic compounds (CVOCs) at a large commercial site in Southern California. The site had a long history of industrial operations, including large-scale degreasing processes at multiple locations.

Scope of Services

Terraphase developed and implemented a focused soil, soil vapor, and perched and regional groundwater investigation to characterize and delineate the nature and extent of trichloroethene (TCE), tetrachloroethene (PCE), 1,1,1-trichloroethane (1,1,1-TCA), and 1,1-dichloroethene (1,1-DCE) impacts from past industrial operations. The project included advancement of soil borings, installation of monitoring wells and multi-depth soil-vapor probes, and coordination with key stakeholders, including multiple commercial tenants, the Federal Aviation Administration (FAA), and airport management, due to some investigation work in proximity to active runways.

The investigation involved advancing over 60 soil borings—many exceeding depths of 100 feet below ground surface—using a membrane interface hydraulic profiling tool (MIHPT) tool to characterize soil and groundwater impacts. Additionally, 14 multi-depth soil-vapor probes were advanced to 85 feet below ground surface, with over 60 soil-vapor samples collected. The investigation included the collection of 40 grab-groundwater samples, and the installation of 8 groundwater monitoring wells. Several of the investigated areas were on airport property, requiring runway closure and night work. The investigations were performed to more precisely define the extent of CVOC impacts; design remedies for soil, soil vapor, and perched and regional groundwater; and support the development of removal and remedial action work plans.

Notable Accomplishments

• Advanced 60 borings across commercial and airport properties, while navigating tenant, regulatory, and airport requirements
• Employed state-of-the-art techniques for sample collection
• Collected quality data in challenging work conditions
• Generated a large dataset to support removal action and remedial action planning

Bellwether District Refinery Redevelopment

Terraphase is the lead environmental consultant for the Hilco Redevelopment Partners (HRP) transformational redevelopment of a former petroleum refinery located on the Schuylkill River in Philadelphia, Pennsylvania. The property will be transformed into a 1,300-acre state-of-the-art e-commerce, logistics, life science, and innovation hub. As one of the largest and most ambitious projects of its kind, the Bellwether District vision exemplifies Terraphase’s and HRP’s shared dedication to environmental, community, and economic sustainability through a comprehensive redevelopment strategy.

Scope of Services

Terraphase implemented a soil sampling program involving the collection of thousands of samples from across the former refinery property to support the site Soil Management Plan and the decommissioning of the refinery infrastructure which included 300 aboveground storage tanks (ASTs) and 950 miles of pipeline.

Terraphase’s responsibilities include soil and groundwater characterization under Pennsylvania’s Land Recycling Program (Act 2), regulatory strategy and representation with the Pennsylvania Department of Environmental Protection (PADEP), risk assessment, non-aqueous phase liquid (NAPL) investigations and management, and real-time perimeter particulate and volatile organic compound (VOC) air monitoring for workers and the neighboring community for HRP’s construction team.

Notable Accomplishments

• Collection of thousands of samples from across the former refinery property
• Decommissioning of the refinery infrastructure which included 300 ASTs and 950 miles of pipeline
• Real-time perimeter air and dust monitoring

Northern California Former Chemical Manufacturing Facility Remediation

This former chemical manufacturing facility, with operations dating back to the 1890s, produced agricultural and industrial chemicals for over a century. In the late 1990s, Terraphase initiated environmental investigations and remedial planning to address legacy contamination under the oversight of the San Francisco Bay Regional Water Quality Control Board (RWQCB) and the California Department of Toxic Substances Control (DTSC). These efforts have guided the site’s transition toward long-term environmental compliance and risk reduction.

Scope of Services

Terraphase investigations included collecting hundreds of soil, groundwater, soil gas, and pore water samples across the site under the oversight of both the RWQCB and the DTSC. The samples were analyzed for volatile organic compounds (VOCs), semivolatile organic compounds, metals, pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and radionuclides to evaluate risks associated with technologically enhanced naturally occurring radioactive material from previously processed ore at the site. The findings demonstrated the site posed no risk to human health.

Terraphase also developed a sea-level rise vulnerability assessment (SLR-VA) using historical and current groundwater elevation data collected at the site, local tidal information, and peer-reviewed sea-level rise scenarios. Terraphase also prepared a human and ecological health risk assessment to identify remedial activities aimed at mitigating risks to future site users. Remedial alternatives were further evaluated in a feasibility study/remedial action plan (FS/RAP).

• Stabilization of pyrite cinders using dolomitic limestone
• Installation of a biologically active permeable barrier
• Design, permitting, and operation of a soil-vapor extraction (SVE) system
• Targeted soil excavations and capping
• In-situ treatment of groundwater VOCs using chemical reduction and bioremediation
• Establishment of engineering controls

Current operations include ongoing maintenance and performance monitoring of the soil-vapor extraction (SVE) system for compliance with the Bay Area Air District (BAAD) permit and implementation of the groundwater monitoring program for continued evaluation of the in-situ remedy performance. In-situ treatment for metals in groundwater will be implemented in accordance with the FS/RAP pending approval of the preliminary design document currently under DTSC review.

Notable Accomplishments

• Stabilized approximately 300,000 cubic yards of pyrite cinders
• Removed approximately 50,000 cubic yards of soil from targeted excavations
• In-situ treatment involved over 700 tons of zero valent iron injected through 950 fractures, and over 250,000 gallons of electron donor and microbial cultures through 182 wells to enhance reductive dechlorination
• Implemented a comprehensive site management plan and requirement of vapor mitigation systems for proposed buildings as engineering controls
• Incorporated a comprehensive groundwater monitoring program consisting of quarterly sampling of 130 monitoring wells and semiannual sampling of subset wells to evaluate the in-situ remedy for VOCs