DNAPL PCE Remediation at Sultan & Sons Utilizing EZVI, EOS Pro, and SDC-9
Douglas Rodgers, P.E., Senior Project Engineer, Aptim Environmental & Infrastructure, LLC
APTIM was retained to implement site restoration after prior remedial efforts utilizing In-Situ Chemical Oxidation did not achieve remediation goals. The property was a former drapery manufacturing facility with subsurface impacts of tetrachloroethylene (PCE) and its reductive breakdown products. APTIM reviewed the prior site documentation and developed a new conceptual site model (CSM) based on experience with similar sites. The updated CSM identified the dense nonaqueous phase liquid (DNAPL) as the dominating site characteristic requiring remediation focus. APTIM designed a remedial injection strategy utilizing abiotic and biotic reductive dechlorination technologies to address the DNAPL source area and the down-gradient dissolved-phase impacts. The design specified the injection of Emulsified Zero Valent Iron (EZVI) to abiotically reduce the DNAPL PCE in the source area and injection of Emulsified Oil Substrate-PRO (EOS PRO) as a reductive dechlorination bioremediation treatment downgradient of the source area. The EOS PRO and EZVI injections were also supplemented with APTIM’s SDC-9 microbial consortium to increase the assurance of complete degradation. Controlled liquefaction injection methods were utilized with individual target injection volumes specified for various depth intervals and locations. The injection activities appear to have resulted in complete DNAPL destruction and substantial reduction of chlorinated impacts across the site. Concentrations of PCE dropped from 159,000 µg/l to 1.9 µg/l in the source area and no longer exceed GCTLs anywhere on the site. This complicated project included various parties including a funding party that was not responsible for the original release, and not the property owner. The impacts extend into the FDOT right of way which was undergoing major highway widening construction. This construction prevented subsequent injection efforts for several years, thus permitting a longer evaluation of the performance of the first injection effort than would normally be provided. The remedial efforts appear to have successfully mitigated the substantial DNAPL PCE impacts with only a single injection event. This presentation will summarize the CSM, the remediation design, the performance results, and the complicating factors and lessons learned to help facilitate future successful remediation efforts.
Mr. Douglas A. Rodgers is a Florida-registered Professional Engineer and a Senior Project Engineer for Aptim Environmental & Infrastructure, LLC (APTIM), leading the engineering team in the Tampa office. Working his way up from a pipe fitter, construction materials laboratory and field technician, geotechnical engineer, regulatory environmental engineer, and remediation design engineer/project manager, Mr. Rodgers brings over 30 years of experience and a wide variety of skill sets to his clients. He is a hands-on engineer with real-world design and implementation experience ranging from in-situ chemical oxidation, biotic and abiotic chemical reduction, remedial excavations, and capping, to a multitude of air sparging and soil vapor extraction systems. He has designed remedial approaches utilizing tiny systems no larger than an office desk, to source removals and capping at small and large facilities, all the way up to super-sized air sparge-soil vapor extraction systems utilizing hundreds of sparge wells. As a former regulatory engineer with the Florida Department of Environmental Protection in Tallahassee, Mr. Rodgers takes great pride in preparing high-quality, pragmatic designs that can be readily approved, while achieving both client and regulatory goals.