September 2015 Prasad Kakarla, PE In-Situ Oxidative Technologies, - - PowerPoint PPT Presentation

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± yd3)
• 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 ft2

• Targeting the 10-20 ft below ground surface (bgs) aquifer interval

(296 yd3)

 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

• f 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

• nths f

fol

• llowing tr

trea eatment t further reduction achieved

• PCE c

concentr trati tion

• ns 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