September 2015 Prasad Kakarla, PE In-Situ Oxidative Technologies, Inc. Lawrenceville, NJ
Holyoke, Massachusetts Former Manufacturing Facility 8.5 acres of land located on a street block, between two canals PCE, TCE, cis-1,2-DCE, and VC PCE concentrations 53,000 µg/l Objective: reduce PCE to below 15,000 µg/l ◦ ½ the GW-3 standard of 30,000 µg/l
Prior site work performed by client includes: ◦ April 2010 – due diligence subsurface investigations conducted on exterior portions of site PCE detected slightly above RC in one shallow well, ND in other wells PCBS, metals, target PAHs detected in some areas ◦ October 2010 – subsequent subsurface investigations across the site PCE detected in shallow well (30 ft from canal) at 49,000 ppb ◦ February 2011 – assessment/delineation of PCE source in groundwater with Membrane Interface Probe (MIP) No significant PCE source identified above water table Suspect DNAPL not identified ◦ July 2011 – off site disposal of impacted CVOC soil (100± yd 3 ) ◦ August – September 2011 – ISCO MFR injections
Modified Fenton’s Reagent (MFR) injections August and September 2011 ◦ PCE largely reduced to below target concentrations and GW did not display elevated PCE concentrations downgradient of recalcitrant source Concentrations reduced through most of the Site. Subsequent sampling in a small hot-spot area indicated PCE rebound above target concentrations in localized area
Performed in December 2012 PCE remediation with following requirements: ◦ Performance-based approach with guaranteed fixed price ◦ Performance-based goal of ½ applicable cleanup standard (i.e., <15,000 ppb) Method 1 GW-3 Standard ◦ ISCO soil mixing approach ◦ Work completed by end of 2012 Hydrated lime activated sodium persulfate
Target treatment area located upgradient of nearby canal and downgradient of newly constructed computing center Area of Concern (AOC) – 20 ft x 40 ft = 800 ft 2 ◦ Targeting the 10-20 ft below ground surface (bgs) aquifer interval (296 yd 3 ) Fine to very fine sand with silt intervals Depth to groundwater approximately 9-11 ft bgs ◦ Generally flows from west to east toward adjacent canal
2009 Aerial Photograph
Clean gravel borrow material (top 3ft) excavated and stockpiled ◦ Additional excavation for proper sloping performed Further excavation within approximately half of the target treatment zone to 10ft bgs (top of the water table) ◦ Clean soils stockpiled in separate location from gravel borrow material ◦ Excavation area known as “Row 2”
Mixing performed in Row 2 first, followed by excavation of clean soils to water table in “Row 1” Unknown concrete pad located approximately 4-5ft bgs in Row 1 ◦ 3,000 lb hammer/breaker used to break pad ◦ Excavated to allow full access to Row 1 target depth Following complete excavation, including removal of concrete pad, mixing performed in Row 1
Excavated area indicates Row 2 Concrete pad over Row 1 location – not yet excavated
Entire mixing area divided into 8 treatment cells ◦ Two rows, each divided into 4 10x10 ft treatment cells ◦ 4 plunges each; 32 plunges total Activities begin in Row 2 ◦ Initial pass throughout entire area ◦ Attempt to homogenize all impacted soil before introducing powdered reagent Hydrated lime blended into cells to raise pH of impacted soils in preparation for sodium persulfate ◦ Tool protection precautionary measure Photo credit: Tighe and Bond
Following hydrated lime introduction and mixing, dry power sodium persulfate introduced and mixed Unexpected reaction by soil ◦ Heaving in and becoming stable again ◦ Resulted in difficulty mixing to depth (20 ft bgs) ◦ Addition of water required to assist LTC blender Mixing approach adjusted for Row 1 ◦ No initial full-row mixing by blender ◦ Both hydrated lime and sodium persulfate introduced and mixed simultaneously ◦ Target depth reached within each cell
17,600 lbs of sodium persulfate; 10,400 lbs of hydrated lime Mixed into treatment area over 3-day period
Following mixing, 3 temporary monitoring wells installed within treatment area 1.5 inch diameter pre-packed screens attached to custom cast iron support beams
Installed using excavator bucket and LTC blender Prior to installation, a long hose was connected to each well so sampling may safely occur
3 days to excavate overburden gravel, stockpile clean soils, and remove concrete pad prior to soil mixing Samples collected by client 14-days following mixing PCE concentrations reduced far below performance criteria (15,000 µg/l) PCE concentration in range of 2,900-3,600 µg/l ◦ Performance standards met 4 additional days utilized to remove temporary wells, fill in and properly ◦ compact excavated area, and install 3 permanent wells 5 mont onths f fol ollowing tr trea eatment t further reduction achieved PCE c concentr trati tion ons 2 s 200-970 µ 970 µg/l ◦
PCE concentrations in groundwater were reduced in AOC by 2 ord rders of mag agnit itude le less than an perf rforman ance-based goal, , with no rebounding, no significant migration of contaminant plume, and no impacts to abutting surface water body!
Spring 2014, project was awarded the Brownfields Project of the Year Award by the Environmental Business Council, New England, Inc. for recognition of the Remediation of the Former Mastex Industries Site and Development of the State-of-the-Art MGHPCC.
Site stabilization issue encountered during Row 2 homogenization pre-reagent mixing ◦ Additional water aided in reaching depth Site mixing plan altered in field for Row 1 Safe simultaneous introduction of L-ASP
ISOTEC EC S Services O es Offer ered ed ISCO and ISCR Bioremediation Metals Treatment Soil Mixing In-Situ Solidification Thermal Remediation www.insituoxidation.com
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