Case Studies
J.S. Held Acquires Shechter & Everett to Expand Forensic Accounting Capabilities for Family Law Disputes in Florida
Read MoreMultiple clients engaged our experts to conduct subsurface environmental assessments for methane at multiple sites in the City of Los Angeles, including properties planned for redevelopment, county facilities, and school sites. The work occurred in areas designated as Methane Zones and Methane Buffer Zones by the City Department of Building and Safety (DBS), which requires methane sampling and mitigation following documented subsurface methane conditions.
In addition to assessment activities, our experts were engaged to manage operation and maintenance (O&M) monitoring at a school site in Playa Vista where a gas mitigation system (GMS) had been installed to control methane, hydrogen sulfide, and volatile organic compounds (VOCs) and prevent accumulation of flammable gas concentrations.
Our experts conducted methane soil gas investigations in accordance with DBS requirements. The team installed both shallow and deep soil gas probes using direct-push drilling techniques and performed continuous sampling as the probes advanced to identify transmissive soil intervals. After equilibration, probes were purged, and methane and oxygen concentrations and differential pressures (subsurface vs. ambient) were measured using calibrated field instrumentation. Where required, hydrogen sulfide and carbon dioxide concentrations were also monitored to evaluate site-specific gas migration conditions.
Our team analyzed methane concentration and pressure data to classify site parameters and determine mitigation measures required by DBS, including sub-slab liners, passive or active collection systems, and trench dams for incorporation into construction plans.
For the Playa Vista school site, our experts conducted quarterly O&M monitoring and reporting for the GMS installed in 2012 and approved for occupancy in 2014. Services included inspection, testing, and monitoring of system components and site conditions, as well as documentation and reporting of results.
Key O&M activities included:
Our experts prepared quarterly reports documenting inspections, monitoring results, and any corrective actions. Monitoring results indicated that methane, hydrogen sulfide, and VOC concentrations remained below site-specific action levels established for the site.
> Environmental Risk and Compliance
Our team provides expert advice in the identification and mitigation of risk in environmental matters and develops solutions to deliver ongoing EHS regulatory compliance and independent monitoring.
> Environmental, Health, and Safety
J.S. Held provides environmental, health, and safety consulting and expert services spanning environmental damage and remediation, environmental due diligence, energy transition, toxicology and epidemiology, industrial hygiene, product stewardship and product liability, and human health and safety.
