The world’s leading sustainability consultancy In Situ Chemical Oxidation of Pesticides Using Shallow Soil Mixing The world’s leading sustainability consultancy William A. Butler, P.E., BCEE; Kevin A. Morris; Richard A. Brown, Ph.D AWMA Southern Section Conference Pine Mountain, GA 19 August 2015

The world’s leading sustainability consultancy Agenda  Background  Closure Strategy  Treatability Study  Remedial Approach  Design & Implementation  Results  Costs  Results Summary

The world’s leading sustainability consultancy Background SITE  Former pesticide blending facility in New Jersey (~4 acres)  Xylene used for applying pesticides  Fire caused a release and triggered an investigation and remediation  Property sold to adjoining airport  Future use for small airplane hangars

The world’s leading sustainability consultancy SITE APPROXIMATE REMEDIATION AREA

The world’s leading sustainability consultancy Background (continued) GEOLOGY Silty, fine- to medium-grained sand Clay aquitard occurring at ~30 ft bgs HYDROGEOLOGY Water table fluctuates between 6 and 12 ft bgs Groundwater flows toward the west-northwest Hydraulic gradient of ~0.001

The world’s leading sustainability consultancy Background (continued) AFFECTED SOIL  Variety of organochlorine pesticides up to 600 mg/kg (avg) Chlordane, Heptachlor, DDT – make up ~70%  Xylenes up to 200 mg/kg (avg) AFFECTED GROUNDWATER  Pesticides exceed aqueous solubility and criteria off site  Xylenes extend off site but below its criterion  LNAPL observed  Co-solvent – presence of xylenes increased dissolved phase pesticide concentrations and mobility

The world’s leading sustainability consultancy Background (continued) PREVIOUS REMEDIAL ACTIONS  Soil Excavation to ~6 ft bgs with off-site T&D  Groundwater Pump & Treat  Electrochemical Geo-Oxidation (ECGO)  Carbon Dioxide Vacuum Stripping (CVS)  Air Sparging/SVE  Saturated zone soil and groundwater pesticide concentration reductions minimal – not enough to satisfy NJDEP

The world’s leading sustainability consultancy Closure Strategy  NJDEP wanted high pesticide and xylene concentrations in saturated zone soil reduced in source area Trend analyses and modelling demonstrated pesticide and xylene plumes were stable No current risk and potential future risks mitigated via institutional controls and future land use as an airport  Negotiated with NJDEP that we would evaluate aggressive in situ remedial technologies, but not excavation Test and implement technology to achieve best results possible and then seek technical impracticability determination Long-term remedy of MNA and institutional controls

The world’s leading sustainability consultancy Treatability Study  In situ chemical oxidation (ISCO) and reduction (ISCR) selected as the most aggressive in situ remedial approaches  Treatability study conducted and base-catalysed sodium persulfate produced best results  pH adjusted to 10 – 11  Reductions achieved after 20 days 90% total pesticides 86% reduction of xylenes

The world’s leading sustainability consultancy Remedial Approach  Project Risk Review and HASP  Remedial Action Workplan  Baseline soil and groundwater sampling  ISCO via shallow soil mixing to reduce contaminant mass  Post soil & groundwater sampling to evaluate performance  Post groundwater monitoring to evaluate natural attenuation  Institutional controls – groundwater and property use restrictions  Long-term biennial groundwater monitoring and reporting

The world’s leading sustainability consultancy Why Shallow Soil Mixing?  Oxidant must come into direct contact with pesticides to maximize effectiveness  Soil mixing is the most cost-effective, aggressive approach to achieve the contact needed  Sulfate and calcium react to form gypsum which helps to stabilize the soil Soil mixing maximizes stabilization after oxidation process is completed Reduces migration potential of remaining pesticides  Increases LSRP and NJDEP confidence in remedy

The world’s leading sustainability consultancy Design & Implementation  Remediation area 0.25 acre and 20 feet deep remove upper 5 feet of clean soil (bermed)  Site preparation install erosion and sediment controls demolish existing building remove underground electric, MWs and other infrastructure  ISCO/shallow soil mixing – Geo-Solutions (subcontractor) hydrated lime ~ 200,000 lb (pH 10-11) sodium persulfate ~ 140,000 lb  Backfill with excavated clean soil and grade/vegetate area

The world’s leading sustainability consultancy Remediation Area MIP Results – represent xylenes Area extended to address pesticides Proposed soil mixing columns

The world’s leading sustainability consultancy Soil Mixing

The world’s leading sustainability consultancy Restored Site

The world’s leading sustainability consultancy Pre- and Post-Soil Analytical Results

The world’s leading sustainability consultancy Groundwater Results

The world’s leading sustainability consultancy Cost Fixed Price Remediation – $858,000 (USD)  $697,000 planning and coordination permitting site preparation implementation restoration  $86,000 pre- and post-remediation soil sampling groundwater monitoring for 2 years  $75,000 design, workplans and report institutional controls/permits

The world’s leading sustainability consultancy Results Summary Good reductions achieved! 68% for total pesticides 86% for xylenes Further reduction expected through sulfate reduction due to residual sulfate remaining after oxidation Pesticide groundwater concentrations decreased by ~90% in 2 years LSRP has agreed to MNA with institutional controls and no active remediation Client released from lease by property owner

The world’s leading sustainability consultancy Thank your for attending! Any questions?