H2A Environmental, Ltd. is an environmental consulting and remediation firm specializing in non-aqueous phase liquid (NAPL) management and risk-based remediation.
NAPL characterization prior to remedy determination is critical in order to understand the nature, distribution, and potential recovery available at a site. NAPL characterization methods H2A has implemented include:
- Soil Borings (direct push and drilled) with field screening and soil sampling
- Detailed Core analyses for NAPL characterization (PTS Labs)
- NAPL Laboratory analysis (viscosity, surface tension, density, profile)
- Well Installation to measure, test and remove NAPL
- NAPL bail down testing to calculate NAPL T/K
- NAPL mobility analyses including modeling under API LDRM
- NAPL head (gradient) maps
- NAPL thickness analyses (correction to in-well thickness exaggeration due to confining conditions)
- NAPL thickness trend analyses under fluctuating water table conditions
- Invented Production Hydrostratigraphs to capture (in one time-series graph) well construction details, stratigraphic boundaries, water/LNAPL elevations, LNAPL thickness trends, and LNAPL production rates
- NAPL in-place volume estimates
- NAPL volume corrections to apparent thickness in wells (DO)
- GIS overlays of structural stratigraphic surfaces with formation thickness isopachs and water/LNAPL elevation maps to identify confined/unconfined aquifer distribution and stratigraphic/structural controls on NAPL migration
- Pilot testing of multiple technologies to identify site hydrogeologic characteristics, NAPL production rates and projected decline curves, NAPL state ratios, radius of influence, radius of capture, zone of influence
NAPL Remedy Selection and Implementation
Risk-based NAPL remedy implementation is gaining momentum on both the state-specific and national level as more information concerning NAPL mobility has been developed. This means that more and more NAPL sites will be remedied with controls rather than removal (or a combination of controls and removal). NAPL is a primary source mass to cross-media human health and environmental impacts. Therefore, in order to implement risk-based NAPL remedies, all aspects of a site’s risk profile must be understood during NAPL characterization. NAPL remedies H2A has implemented include:
- Technical Impracticability (TI) Demonstrations
- NAPL migration controls
- NAPL extraction via total fluids pumping (single or dual pump(s))
- NAPL extraction via soil vapor extraction (SVE)
- NAPL extraction via two-phase extraction (TPE) – high and low vacuum applications, mobile and fixed base systems, unconfined and confined conditions
- NAPL extraction via dual-phase extraction (DPE) – high and low vacuum applications, mobile and fixed base systems, unconfined and confined conditions
- NAPL extraction via vacuum-enhanced skimming (VES)
Risk assessment programs nationwide are typically based on national standards but frequently modified at the state level. Risk is the driver for site remedy selection. If there is no unacceptable risk, then no remedy is required. Alternatively, risk-based remedies where concentrations of chemicals of concern exceed health and/or ecological based reference values may include controls, removal or a combination of controls and removal. Implementation of removal remedies in particular can be costly. Therefore, a correct evaluation of a site’s risk-based cleanup values can potentially save millions of dollars in cleanup costs.
Risk assessment is data intensive and mathematically driven. Consequently, it is ideally automated via data management systems. H2A is well known for its automated database-driven commercial software for the Texas Risk Reduction Program (TRRP). Currently, H2A is developing national level risk assessment automation software to link to enterprise level data management systems.
H2A’s risk assessment software automates data management, calculations, and reporting. But it cannot replace the expertise of a skilled risk assessor. For example, soil pH under Tier 1 analyses can change the reference value for mercury, but many consultants don’t realize they must adjust to soil pH to derive the correct reference value. Many other far more complex issues may arise. Knowledge, experience, the proper evaluation tools, and an innovative mind are critical to provide maximum value to clients by maximizing site cleanup values that are still protective of human health and the environment.
Data Management Services
H2A has developed numerous database-driven software programs for extensive characterization and remediation data. H2A has also developed custom data management solutions for Fortune 500 companies’ environmental data. At the enterprise level, H2A maintains an in-house EQuIS Pro license and is currently developing custom and commercial data management solutions that link seamlessly to EQuIS.