µg/L
In-Situ Remediation of Hexavalent Chromium, Antimony and Nickel with Sub-Micron (Nano)-Scale Ferrous Sulfide Slurry
Jim V. Rouse, Richard H. Christensen, PhD LPG,
& Steven R. Irvin (AcuityES, Fishers, IN)
© AcuityES 2013
Company’s Primary Focus: • Environmental Liability Consulting (how to manage liabilities) • Site Investigation – Soil, Groundwater, Air • Remediation of contaminated Sites • Expert Witness Testimony
Company’s Secondary Focus: • Environmental Permitting – Air, Water, Waste • Environmental Compliance
Acuity Environmental Solutions
© AcuityES 2013
Presented At: • International Seminar on Remediation and Redevelopment of
Contaminated Sites, Sao Paulo, Brazil • AEHS West Coast Conference, San Diego, CA • USEPA’s Sustainable Remediation International Conference, Amherst, MA • AWPA National Conference, Ft. Lauderdale, FL & Nashville, TN • Midwest States Environmental Consulting Assoc., Indianapolis, IN • Battelle Conference, Monterey, California
In-Situ Remediation of Hexavalent Chromium, Antimony and Nickel with Nano-Scale Ferrous
Sulfide Slurry
© AcuityES 2013
Case Study In… In Situ Geochemical Reduction
Stabilization (i.e., immobilizing) of metal constituents by chemically reducing the metals of concern to less soluble forms through the manipulation of geochemical factors such as:
• pH • Oxidation potential (Eh or ORP) • Complexation • Sorption • Ion exchange
Resulting in the elimination of metallic contaminants by: • Precipitation • Dissolution • Oxidation • Complexation
© AcuityES 2013
Key Project Considerations Competitor’s Proposals for Project included: • Off-site disposal of hazardous soils • 15 - 20 year pump and treat remedy for groundwater • >$8 Million
Note: original estimates based on >50% smaller source area Our Solution: • In Situ remediation of impacted soils and groundwater • Goal: 2 year total remedy - 1/8th the time - • Cost: $4.5 Million - Nearly 50% below competitor’s bids -
© AcuityES 2013
First things first…
Interior Building Decontamination
Segregation of Waste for Disposal
Building Demolition
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Soil Boring & Well Installation
Groundwater Sampling
Soil Sampling
First things first…
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Site Plan for X-Section Line
Site Conditions First investigation – 2005 AcuityES - 2009
A’
A
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Hydrogeology
Unconfined Aquifer Clay to 15 feet (w/stringers) Sands & fine gravels Static Water at 15’ bgl Saturated thickness 5’ in SE to > 25’ in NW
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Soil Impacts
• Two Adjacent Source Areas • 5,400 cubic yards of impact • Perched water sand stringers
7,900 mg/Kg maximum Cr+6
3,600 mg/Kg Cr+6 at 12’ bgl
State Cleanup Goal - 38 mg/Kg
© AcuityES 2013
Groundwater Impacts
Groundwater COCs Cr+6, Sb, As, and Ni
On-Site Cr+6
800,000 µg/L
9,700,000 µg/L
66,000 sq ft (320 ft long) Plume Offsite Cr+6 at 58,800 µg/L
State Cleanup Goal- 100 µg/L Cr+6
© AcuityES 2013
In Situ Chemical Reduction
•Ferrous Sulfate : FeSO4·7H2O
•Ferrous Sulfide : FeS
•Calcium Polysulfide (CPS) : CaSx
•Sodium Thiosulfate : Na2S2O3
•Sodium Metabisulfite : Na2S2O5
•Sodium Sulfite : Na2SO3
•Zero Valent Iron
BENCH TESTED CHEMICALS REDUCTANTS
© AcuityES 2013
Selected Ferrous Sulfide (FeS)
FeS, Hybrid Form (aka precipitated pyrite)
Liquid suspension of 7% FeS FeS, hybrid - With additional 2% free Sulfide to simulate CaSx Nanoscale: 98% crystals <5 microns Cationic (Iron) 4 H2O + Cr04
2- + 3 Fe2- + 4 OH- 3 Fe(OH)3+ Cr(OH)3 (Solid) Anionic (sulfide) 17 H2O + 8 Cr04
2- + 3 HS- 3 S + 8 Cr(OH)3 (Solid) + 12 OH-
© AcuityES 2013
In Situ Soil Blending
Dual Axis Blender – 15’ Plunge Total Area – 130’ x 110’
GPS Grid Network – 10’ x 10’ (100’ x 70’ to 15’) & Shallow to 5’
Computerized Dosing
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In Situ Soil Blending Completed in 2 weeks Total FeS = 78,300 gallons Subsequent stabilization with aglime required
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Groundwater Injections
Difficult Injections
Boulder Fields
6’ caliche
(calcified silt)
Lodgement till
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Groundwater Injections
FeS Injection Totes 35,385 gallons injected
Rotosonic Drilling Top Down Injection – 5ft intervals
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Antimony Treatment Antimony Concentrations: Detected in 25 monitoring wells on-Site up to 30,000 µg/L off-Site up to 4,700 µg/L State Industrial Cleanup level - 41 µg/L State Residential Cleanup Level - 6 µg/L Goal for Antimony: Fixate onto Goethite (FeO(OH)) or Precipitate as stibnite (Sb2S3)
© AcuityES 2013
4th - 10th Q Post-Treatment Antimony
All results less than method
detection level of
6 µg/L
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Nickel Treatment Nickel Concentrations Detected in 10 wells exceeding cleanup levels off-Site up to 4,100 µg/L on-Site up to 50,000 µg/L State Industrial Cleanup level – 2,000 µg/L State Residential Cleanup Level - 730 µg/L Goal for Nickel: Fixate as: westerveldite ([FeNiCo]As) or pentlandite (FeNiS)
© AcuityES 2013
1st Q Post-Treatment Nickel
All results less than method
detection level of
50 µg/L
No subsequent detections
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Arsenic Arsenic – Pre-treatment As detected in 13 wells @ concentrations of 11 µg/L to 360 µg/L 10th Quarter Sampling results: only 2 wells @ 11 & 12 µg/L Goal for Arsenic Fixate as: orpiment (As2S3) or arsenopyrite (FeAsS)
© AcuityES 2013
ISCR Benefits 1. In situ soil blending eliminated need for off-Site
hazardous waste disposal. (> 10,000 Tons)
2. In situ groundwater geochemical reduction eliminated need for prolonged pump and treat.
3. In situ geochemical reduction reduced time period of remediation from > 15 years to about 2 years.
© AcuityES 2013
CONTACT Richard H. Christensen, PhD, LPG – [email protected]
Steven R. Irvin – [email protected] Jim V. Rouse – [email protected]
317-570-4919
Past Teaming Partners
CDM Mundell & Associates Burns & McDonnell CALIBRE Professional Engineers MWH Global Malcom Pirnie V3 Consultants
www.acuityes.com © AcuityES 2013