Remediaton Group Manager and Senior Project Director
TRC Environmental Corporation
Brendan Lazar currently serves as the Remediation Group Manager and a Senior Project Director in the Engineering Division of TRC’s Environmental Remediation Practice in New Providence, New Jersey. He is a licensed Professional Engineer in New Jersey and maintains LEED Green Associate certification. Mr. Lazar earned a Bachelor of Science in Bioresource Engineering from Rutgers University and a Master of Science in Civil and Environmental Engineering with a minor in Microbiology from Cornell University. Mr. Lazar volunteered for the NJDEP’s Conceptual Site Model Guidance Document committee, volunteers for the ITRC team for Optimization of In Situ Remediation Performance and Injection Strategies, routinely provides guest lectures at Rutgers University and Cornell University, and actively contributes to professional conferences and publications. When not developing remedial strategies, Brendan enjoys spending time with his family and various outdoor activities like cycling, mountain biking, running, hiking, skiing and fishing.
Innovative Reagent Design for Hexavalent Chromium Treatment in a Strongly Acidic Environment
Authors: Nidal Rabah, PhD, PE, Brendan Lazar, PE, LEED GA, Robert Stanforth, PhD, and Eric Baumgarten, LSRP (TRC)
A comprehensive laboratory treatability study and field pilot tests were implemented to evaluate the effectiveness of an innovative chemical reagent suite for in-situ remediation of elevated hexavalent chromium [Cr(VI)] impacts (>1,000 ppm in soil and groundwater) at an industrial facility in New Jersey. Cr(VI) impacts are detected in the vadose and saturated zones in a strongly acidic environment (pH=1.5-4 s.u.). Soil impacts are detected just below surface and extend below the water table (15 feet below grade). The source zone is located under an active area of operations inside a building with significant access constraints. A 7-acre, 60-foot deep groundwater plume is present within the interlayered beds of sand, silt and clay of the Potomac-Raritan-Magothy aquifer, the most heavily pumped in New Jersey.
The selected remedy consists of in-situ geochemical manipulation. A design using an infiltration system for the vadose zone at the source and a downgradient in-situ reactive zone for groundwater was necessary to address potential Cr(VI) leaching from the vadose zone and challenging shallow impacts, access constraints, and hydraulic and geochemical conditions.
Extensive batch and column tests were designed to determine the reagents, reagent doses, and delivery strategies. Chemical reagents evaluated include ferrous iron with magnesium hydroxide, calcium polysulfide (CaSx), and ferrous sulfide (FeS) formed from combining CaSx and ferrous sulfate heptahydrate (FSH). The column tests included down-flow and up-flow systems to simulate reagent infiltration through the vadose zone and groundwater flow through an in-situ formed reactive zone, respectively. The tests evaluated the hydraulic performance, geochemical changes and treatment efficiency related to each reagent and system. Infiltrating CaSx provided effective pH buffering and Cr(VI) treatment in the vadose zone with no clogging. FeS performed the best for longer-term (14 pore volumes) treatment of groundwater fluxing from the source zone.