Demonstration/Validation of Long-Term Monitoring Using Wells Installed by Direct-Push Technologies

摘要

An ESTCP sponsored multi-site Long-Term Monitoring (LTM) project has been conducted to determine whether there is significant statistical difference between groundwater monitoring results obtained from direct-push and conventional hollow-stem auger installed wells. Five field sites are included in the study to represent a variety of geologic conditions as well as a cross- section of regulatory domains (e.g., EPA regions and states). Direct-push wells have been installed adjacent to, in well pairs or clusters, existing hollow- stem auger drilled wells. Thirteen sampling events over a five year period (Phase I & II) have been completed at the sites in which groundwater samples have been analyzed for parameters typically examined with long-term site compliance monitoring including chemical concentrations, oxidation-reduction potential (ORP), pH, temperature, conductivity, turbidity, and dissolved oxygen (DO). The target analytes for this project include: PCE, TCE, cis-DCE, trans- DCE, VC, BTEX, DCB, TCA, and MTBE. ANOVA statistical methods have been employed to address a wide range of inherent variables such as well depth, screen length, filter packs, annular sealing, spatial and temporal heterogeneity, groundwater seasonal changes, plume characteristics, and geological conditions. Inorganic data was also collected on an annual basis to assess the performance of the direct-push well for monitored natural attenuation at the five test sites. Additionally, the ESTCP LTM project team partnered with the Interstate Technical Regulatory Council (ITRC) Sampling, Characterization and Monitoring (SCM) team to product a Direct-Push Well Technology Technical/Regulatory Guidance Document and internet training module.