Licensed Site Profession (LSP) Services In-Situ Chemical Oxidation Treatment
BETA provided LSP services for the response to an underground storage tank (UST) release that resulted in No. 6 heating oil in site soil beneath a branch of a regional bank and an abutting historic downtown Attleboro commercial building.
BETA directed the removal of the UST and upon discovery of the oil release, assessed its extent by the installation of 27 soil borings and 19 monitoring wells. The release resulted in the presence of No. 6 heating oil at depths of 10 to 22 feet and Light Non-Aqueous Phase Liquid (LNAPL) in site monitoring wells, including over 30 inches in one well. BETA prepared an Immediate Response Action Plan and MCP Phase I-IV reports for submittal to MassDEP. Due to the depth of the release, the presence of LNAPL, and the limited access for excavation, BETA determined that in-situ remediation was the most practical means of responding to the release. BETA retained MECX, LLC of Houston, Texas to design and implement an in-situ chemical oxidation treatment using hydrogen peroxide catalyzed sodium persulfate. BETA, acting as the general contractor, provided all site specific information, LSP services, client contact, field assistance, and post-treatment monitoring and reporting.
Preparation for the project required performing a bench-scale test of the proposed oxidants on samples of site soil and groundwater, obtaining DEP approval, local permits for temporary chemical storage and hydrant use, notification to abutters, and determining pre-injection baseline environmental conditions. MECX coordinated the delivery, injection, and monitoring of 8,900 gallons of 17% hydrogen peroxide and 990 pounds of sodium persulfate over an eight-day period. The treatment was immediately successful in decreasing the thickness of LNAPL in site monitoring wells to less than 1/2 inch. BETA collected groundwater samples, which confirmed that no petroleum constituents migrated beyond the release area. BETA is currently performing long-term monitoring prior to submitting the Final Response Action Outcome Closure Report.