St Stabiliz ilizatio ion/Solid lidif ific icatio ion ( (S/S) - - PowerPoint PPT Presentation

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St Stabiliz ilizatio ion/Solid lidif ific icatio ion ( (S/S) S/S) V Valu lue E Engin ineerin ing StudyPes St esticide I de Impact cted L d Lagoon M n Mater erials Dennis G. Grubb, PhD, P.E. Former CH2M HILL Principal

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St Stabiliz ilizatio ion/Solid lidif ific icatio ion ( (S/S) S/S) V Valu lue E Engin ineerin ing St Study—Pes esticide I de Impact cted L d Lagoon M n Mater erials

RE3 2015 Conference September 16, 2015

Dennis G. Grubb, PhD, P.E.

Former CH2M HILL Principal Technologist

Dusty D. V. Berggren

CH2M HILL Project Engineer

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Several mg/L BHC compounds (Lindane)

Pesticide-Impacted Confidential PRP Site E1315 testing on pesticide-impacted residues

Told not to run totals (mg/kg) or we would ruin our analytical equipment Concern: SPLP has tendency to lead to reagent overdosing

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Pesticide-Impacted Confidential PRP Site Lagoon Area with Pesticide-impacted residues

  • Lagoon over shallow bedrock (24,000 CY)
  • VOCs, SVOCs, pesticides (wt%) as main COCs
  • Upper Fill, Residues/powders, Residual soil
  • Key COCs
  • BHC compounds
  • Chlorinated benzenes
  • Contractor treatability study
  • SPLP results used for mix design selection
  • proposed 2% GAC
  • Reagent cost: $0.75/lb; $50/CY treated
  • CH2MHILL conducted supplemental study
  • SPLP vs. E1315 leaching tests
  • % Reduction basis
  • Reduce or eliminate GAC%

Cohesive residue materials highly plastic, had to be peeled

  • ff of augers
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Comparing EPA Methods 1312, 1315 and 1315M

  • Method 1312 (SPLP):

‒ Simulates acid rain exposure ‒ Extraction fluid based on buffer capacity of waste ‒ 100% passing 3/8-inch sieve ‒ L:S ratio 20:1; 18 hours contact time, 1 data point

  • Method 1315 (Semi-Dynamic Leaching)

‒ DI Water leach ‒ L:S ratio 10:1; 2 hour to 14-day contact time; ‒ Total duration between 60 to 90 days; 9 min data points

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EPA 1315 and EPA1315M

  • EPA Method 1315 (Semi-dynamic Leaching)

‒ Rates of diffusion through solid ‒ Inorganic species only ‒ Monolithic or compacted granular materials ‒ DI water leachant at 9 mL/cm2 surface area ‒ 9 intervals; 2-hr to 14-day; total of 63 days ‒ Extend leaching intervals as needed

  • Method 1315M (Semi-dynamic Leaching)

‒ Modification to address VOCs & SVOCs ‒ Uses polydimethylsiloxane (PDMS) jar liner ‒ PDMS acts as infinite sink for VOCs/SVOCs ‒ ZHE configuration ‒ Analyze water bath and extract PDMS

  • MeOH for VOCs
  • Acetonitrile for SVOCs/pesticides
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Method 1315M Water Bath Concentrations vs Effective Concentrations (water + PDMS liner)

Since ANSI 16.1 does not use a PDMS liner, water bath concentrations of VOCs & SVOCs can reach effective water saturation (e.g. SPLP of untreated material), reducing the measured release from the material and invalidating the assumptions of the test.

In 1315M PDMS acts as a sink for organics, suppressing water bath concentrations and maintaining strong concentration gradient.

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Site Profile and TS Objectives

  • Blending proportions based on LA31 location
  • Upper Fill (UF)

(1/6) 4 ft thick

  • Powder Paste (PP) (1/3)

8 ft thick

  • Residual Soil (RS) (1/2)

12 ft thick

  • UF and PP screened for oversize & fibers
  • Contractor treatability study
  • SPLP results used for mix design selection
  • proposed 9% PC/SC plus 2% GAC
  • Reagent cost: $0.75/lb; $50/CY treated
  • CH2 conducted parallel study
  • SPLP vs. E1315 leaching tests
  • % Reduction basis
  • Reduce/eliminate GAC based on more

appropriate testing protocol

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SPLP Results on 28-day cured samples 2% GAC ASL treatment versus WRS field samples

  • SVOC data similar
  • Most pesticide data similar

except BHC

  • Most VOC data similar except

TCB, DCB

  • Why?
  • Key Differences…
  • ASL very homogenized
  • Field heterogeneity
  • >50% of upper soil &

cobbles removed in field

  • LA31 depth approximately 4

to 18 ft bgs in field

  • Powder paste >50% of

waste mass in field

  • Powder paste ~33% in ASL

surrogate

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SPLP Results on 28-day cured samples

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Alkaline Hydrolysis of BHC Compounds

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  • Minor detection of chlorobenzenes under

natural conditions (biotic transformations at near neutral pH)

  • Alpha, delta, gamma BHC undergo alkaline

hydrolysis or “Dehydrochlorination.” At high pH:

  • H, Cl cleaved from hexane ring
  • Benzene ring formed
  • First byproduct is trichlorobenzene (TCB)
  • Chlorinated phenols can also result
  • GAC is catalyst for reaction
  • BHC compounds should leach at lower

concentration or slower than “diffusion controlled” conditions.

  • Chorobenzenes (less hazardous) should

“appear” in mix design SPLP and E1315 data.

Source: Kubatova et al 2002

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Transforming SPLP (mg/L) to mass flux (mg/m2)

Upper Table:

  • Use site K, gradient,

soil density to get “elapsed time” to attain the L:S=20:1 used by SPLP test, assuming saturated flow conditions Lower Table:

  • Estimate mass flux

(mg/m2) for each COC for each elapsed time used to bracket expected site conditions (depends

  • n K, v, gradient, neff)
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Select E1315 data--Gamma BHC

  • Gamma BHC leaching (flux) looks to be largely

diffusion controlled. Approaching 90% reduction

  • f untreated site transformed SPLP data.
  • Minor differences (2x to 4x) between 0% to 2%

GAC, both well below SPLP data.

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Select E1315 data—Delta BHC

  • Delta BHC leaching (flux) looks to

be significantly diverging from expected diffusion controlled condition.

  • Since high initial concentrations,

could be key contributor to TCB generation.

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Select E1315 data--Trichlorobenzene

  • TCB release greatly exceeds

diffusion controlled leaching rates

  • wing to its creation. Exceeds

site transformed untreated SPLP data because of low initial concentrations.

  • Very minor differences in GAC
  • content. GAC limited catalyst?
  • Reactions in water bath?
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Select E1315 data– gamma BHC interval flux

  • Gamma BHC leaching (flux) looks to be largely

diffusion controlled.

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Select E1315 data– TCB interval flux

  • TCB leaching (flux) is constant to slightly

increasing, greatly exceeding diffusion controlled conditions.

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COC % Reduction Comparison

  • Confirmed Contractor SPLP performance
  • E1315 results showed much better removal than E1312 (SPLP) results for same mix designs
  • Recommended elimination of 2% GAC at expected cost of $1.17 to $1.55 million (reagent cost only).
  • Provided mass fluxes to be used in subsequent GW modeling activities for POC evaluations.
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Thank Y You

  • u For
  • r You
  • ur T

r Time

Robert Cipolletti, CPG Commercial Technology Manager

Direct: 774-284-4633 bob.cipolletti@ch2m.com